Hi Everyone,
Here’s Donald Sutherland’s Winter Weather Column for January. He’s certainly has a ton of great insight into how weather patterns may trend.
In case you want to go back and read over his posts from previous months check out the following
– November
– December
************************************************************************************************************************************************Posted Friday, January 31 @ 11:26 AM
January 2014 ending after Highlight Cold…
During January, numerous cities saw their coldest 10-day stretch in almost a decade or longer. In addition, monthly snowfall allowed many cities to build large anomalies above normal snowfall to date. Below is a table that provides related data for select cities:
Ice-covered Hudson River (Sleepy Hollow, New York)
************************************************************************************************************************************************Posted Thursday, January 30 @ 8:30 AM
Morning thoughts…
1. In the wake of the snowstorm, temperatures plunged into the single digits across parts of the Mid-Atlantic region and below zero in a few spots. Some highlights:
Atlantic City: -3° (Broke daily record of 5° set in 2000; 2nd subzero reading of the winter and the most since winter 1995-96 when there were 3)
Baltimore: 5° (10th single-digit reading of the winter and the most since winter 1981-82 when there were 10)
Norfolk: 6° (Broke daily record of 10° set in 1934 and the 1st single digit reading since 1/191994 when the temperature fell to 5°)
Raleigh: 7° (Tied daily record of 7° set in 1977; 2nd single digit reading of the winter and the most since winter 1999-00 when there were 2)
Richmond: 4° (2nd single digit reading of the winter and the most since winter 1999-00 when there were 2)
2. The much colder than normal regime will now relax and temperatures will moderate through the first 5-7 days of February. The relaxation looks to be temporary.
3. The biggest snows still lie ahead in the 1/25-2/15 period that has looked snowy for some time from the Midwest to the northern Mid-Atlantic and New England states and perhaps farther south. The 2/8-15 period appears to have the best prospects for heaviest snows as the subtropical jet should be active and the cold should be reasserting itself.
4. The overall pattern evolution seems to be unfolding reasonably similar to 1899 albeit without the kind of extreme-to-historic cold seen that winter. That evolution also saw a temporary period of moderation followed by snowfall and severe cold. That kind of evolution still looks good on a lot of the guidance, even as day-to-day details remain to be resolved. The ensembles also suggest a renewed Arctic assault in the extended range. Hence, cities such as Baltimore, New York, and Philadelphia likely have not seen their last single-digit readings of the winter.
************************************************************************************************************************************************Posted Tuesday, January 28 @ 10:18 AM
February 8-15, 2014 Thoughts:
Two words sum up the idea for a large part of the eastern CONUS: “Cold” and “Snowy.”
In discussions in this thread, the January 25-February 15 timeframe was highlighted as one that would likely see above normal snowfall in the eastern CONUS, particularly areas that had already seen above normal snowfall (Midwest, Great Lakes, northern Mid-Atlantic, and New England). So far, that period is off to a good start for the most part.
Select Snowfall since January 25:
Boston: 0.1″
Detroit: 8.8″ (bringing 2014’s record January figure to 38.3″)
New York City: 1.0″
Newark: 1.0″
Philadelphia: 2.4″
Today into tomorrow, a snowstorm will rage across parts of the South. Cities such as Raleigh and Norfolk will pick up a significant snowfall. The potential exists for Norfolk to receive 10″ or more snow.
With the subtropical jet showing some signs of life and very cold air remaining locked in over Canada and the northern tier of the U.S. courtesy of linked blocking from the EPO- to the AO-, this period will likely feature abundant snowfall opportunities (probably beginning around February 5-6). Renewed cold should also reassert itself. The possibility exists for a bout of severe cold that could send temperatures back into the single digits in the Mid-Atlantic region and below zero in the Midwest, Plains States, and Great Lakes region.
Below are the maps for the teleconnection cases that had a reasonable match with the January outcomes to date and the GFS ensembles at 360 hours (middle of the 2/8-15 period):
Based on the ensembles (ECMWF and GFS), recent runs of the operational GFS, and the teleconnection cases above, I expect the following anomalies:
Western Canada: Near Normal
Rest of Canada: Colder than normal
Western third of the CONUS: Above normal
Southern Plains: Near normal in the north; colder than normal to the north
Northern and Central Plains eastward across the Midwest and Great Lakes/Ohio Valley to the Mid-Atlantic and New England: Colder than normal
Southeast: Near normal in the north; warmer than normal in the south (particularly the Gulf Coast and Florida)
The second half of this discussion is devoted to the possible pattern evolution through the period and somewhat beyond. Although 1899 is referenced, one should not expect the same kind of extreme Arctic outbreak seen during that case. The February 1899 Arctic outbreak was one of the benchmark Arctic outbreaks during the past three centuries in North America. Instead, the pattern evolution might provide some insights related to the return of severe cold (perhaps comparable to that seen this month) and snow (consistent with what was described above).
Yesterday, in the Southeastern Region discussion, I noted that some of today’s daily snowfall records were set in 1899.
Following the storm, 1899 saw a relaxation of the cold. The February 2-5 period saw temperatures soar as high as 63° in Richmond. However, the cold returned beginning February 6 and the February 8-15 period proved severely cold.
If one examines the temperature anomalies shown on the teleconnection cases cited above and those during the somewhat larger February 1-5, 1899 period, one finds a reasonable match.
Similarities also show up at 500 mb:
What this situation implies is a possible scenario where:
1. The relaxation in the cold for the first 5-7 days of February could be temporary
2. Colder anomalies return at some point afterward with the potential for severe cold increasing during the second half of the 2/8-15 period and possibly afterward
3. Above normal snowfall in the eastern CONUS with the potential of a significant storm (especially if the subtropical jet comes to life as currently modeled).
************************************************************************************************************************************************Posted Monday, January 27 @ 12:37 PM
January 28-29, 2014 Southern Snowstorm:
Based on the latest ensemble and operational model guidance (prior to the 1/27 12z run of the ECMWF), one could probably make a case that the February 6-7, 1980 and March 1-2, 1980 snowstorms had reasonably similar 500 mb patterns. Below are charts showing the composite 500 mb anomalies for those two storms and qpf/snowfall for select cities:
Taking into consideration those 500 mb cases and the latest guidance, snowfall risks can probably be listed as follows:
Trace or Less:
Boston
New York City
Philadelphia
Washington, DC
1″ or Less:
Atlantic City
Birmingham
Savannah
1″-3″:
Atlanta
Charleston
2″-4″:
Charlotte
Columbia
Richmond
Wilmington, NC
3″-6″:
Raleigh
6″ or More:
Norfolk
************************************************************************************************************************************************Posted Sunday, January 26 @ 7:38 PM
1/27-29/2014 Precipitation in the Deep South:
Per Bufkit soundings:
Charleston: Some sleet and a lot of freezing rain
New Orleans: Sleet, freezing rain, and then accumulating snow (possibly several inches)
Savannah: Some sleet and a lot of freezing rain
************************************************************************************************************************************************Posted Sunday, January 26 @ 6:23 PM
1/27-29/2014 Precipitation in the Deep South:
Per Bufkit soundings:
Charleston: Some sleet and a lot of freezing rain
New Orleans: Sleet, freezing rain, and then accumulating snow (possibly several inches)
Savannah: Some sleet and a lot of freezing rain
************************************************************************************************************************************************Posted Sunday, January 26 @ 6:23 PM
February 2014 Thoughts…
Recent weeks have seen a rather dramatic cooling in ENSO Region 3.4. This is one signal of a cooler than normal February across the eastern half of the CONUS. Winters that preceded the development of an El Niño that had a January-March ENSO Region 3.4 anomaly of > 0°C typically featured a lot of warmth in February (1957 and 2002). Those that had an anomaly of < 0° often featured a lot of cool anomalies in February (1965 and 1968).
At the same time, the strong positive SSTAs in the Gulf of Alaska will likely help sustain a the general EPO- regime that has persisted with only a few interruptions this winter. In addition, there is growing support among the ensembles that the Arctic Oscillation will be predominantly negative for at least the first week or two of February.
Below are charts based on past years with similar teleconnections, similar teleconnections following reasonably similar January temperature anomalies across North America, and the CFSv2 forecast:
Given the ensembles for the opening of February and the above charts, I suspect that a large part of North America will likely see a colder than normal February. There could be some moderation, particularly during the first week of the month, but it would not surprise me if that moderation were followed by another bout of severe cold. The first half of February could also feature above normal snowfall in areas that are running above normal, including Chicago, Detroit, New York City, Newark, Philadelphia, and Boston. The possibility exist that the above normal snowfall could also impact Baltimore and perhaps Washington, DC during February, especially if the AO goes strongly negative as a few ensemble members imply.
Overall, in terms of temperature anomalies, I expect:
Pacific Northwest/western Canada: Near Normal
Southwest/Southern Plains: Warmer than normal
Southeast: Warmer than normal
Northern Plains, Central Plains, Great Lakes Region/Ohio Valley, Mid-Atlantic, and New England: Colder than normal
Eastern Canada, except the Atlantic provinces and extreme northern areas: Colder than normal. The excepted areas should wind up warmer than normal, especially if strong blocking develops.
************************************************************************************************************************************************Posted Sunday, January 26 @ 11:56 AM
Morning thoughts…
1. The ensemble guidance continues to point to an EPO-/AO- pattern for the extended range.
2. The pattern will very likely feature a relaxation of cold near or at the end of January into the beginning of February. The first week of February should still wind up colder than normal in much of the eastern half of the CONUS. This relaxation does not mean that winter is over, much less that February will be warmer than normal.
3. Snowfall for such cities as Chicago, Detroit, Philadelphia, New York, and Boston still looks to be above average for the January 25-February 15 period.
************************************************************************************************************************************************Posted Saturday, January 25 @ 9:29 AM
Some morning thoughts…f
1. With this morning’s light snowfall, it appears that Detroit has set a new January snowfall record.
2. Given the forecast teleconnections (EPO-/AO-), there is no need right now to panic about the sudden turn to warmer conditions on the extended range GFS. Some moderation, but not sustained warmth appears more likely. I have no changes in my thinking that the Midwest to the northern Mid-Atlantic/southern New England areas will see above average snowfall for the 1/25-2/15 timeframe.
3. Odds continue to favor a lot of cold in Canada and the CONUS for February.
************************************************************************************************************************************************Posted Friday, January 24 @ 2:09 PM
1/28-30/2014 Arctic Blast in the South:
As had been noted in Message #604, the GFS ensembles showed temperatures falling 3 or more standard deviations below normal across parts of southern U.S. running from Texas to Georgia for the January 28-29 timeframe. It should be noted that the 12z runs of the operational GFS and ECMWF are somewhat more restrained. Therefore, cold temperatures in the 1.5-2.0 standard deviation range might be more likely than those in the 2.5-3.0 standard deviation range.
Below are the GFS ensemble mean 850 mb forecast and also high and low temperatures that correspond with the standardized anomalies. The last chart shows the lowest minimum and maximum temperatures reached so far this winter.
************************************************************************************************************************************************Posted Friday, January 24 @ 10:31 AM
Morning Thoughts…
1. The GFS ensembles now show temperatures falling 3 or more standard deviations below normal across parts of southern U.S. running from Texas to Georgia for the January 28-29 timeframe. More on that will be posted this afternoon.
2. To date, cities such as Chicago, Detroit, Indianapolis, Philadelphia, New York, and Boston have seen above normal snowfall. January snowfall has been excessive in Chicago (30.3″, 4th highest January figure) Detroit (29.2″, 2nd highest January figure and just 0.4″ short of the monthly mark from 1978), Indianapolis (24.9″, 3rd highest January figure), and Philadelphia 22.5″ (5th highest January figure).
3. To date, winter 2013-14 has featured the most severe cold in at least a decade in many major Midwestern and Eastern cities and, in cases, longer. For example, Baltimore has had 8 single-digit low temperatures, it most since 1993-94 when that city also had 8.
Going forward, next week will feature additional severe cold (point #1). Some of the long-range guidance also hints at opportunities for severe cold in February with perhaps the 1/24 6z GFS showing among the most extreme solutions.
The operative question concerns how will this severe cold end? Going back to a number of winters that featured severe cold for an extended period or frequent bouts of severe cold, there are three major scenarios:
1. A significant snowfall near or after the worst of the cold.
2. Frequent light to moderate snowfalls following the worst of the cold.
3. A relative quiet ending with some late-season snows or a late-season cold shot.
Below is a table for select cases:
************************************************************************************************************************************************Posted Thursday, January 23 @ 12:10 PM
Arctic Blast of 1/26-29/2014:
The GFS ensembles, with strong support from the ECMWF ensembles, are indicating that a very cold air mass will plunge into CONUS, with the coldest anomalies impacting the Midwestern and portion of the Southern states. The peak standardized anomalies could be 2-3 standard deviations below normal.
This would translate into near record or possibly even record cold for a number of cities. Below are some high and low temperatures associated with the standardized anomalies for select cities, along with the coldest readings so far this winter and daily record low minimum and maximum readings for 1/28-29:
************************************************************************************************************************************************Posted Wednesday, January 22 @ 9:45 PM
February 1-7, 2014 Thoughts…
The cold that developed following the thaw that dominated the second week of January appears likely to persist through much of the first week of February in a large part of the eastern U.S. and Canada. The notable exception will likely be western Canada and the western United States.
The GFS Ensemble 11-day objective analogs rolled forward to 2/4 and teleconnection cases that have had the best fit to January both hint at the development of a February 1994-type gradient pattern. Whether such a pattern emerges during the latter part of the first week of February or shortly thereafter remains to be seen. Nevertheless, I suspect that the first week of February will have the potential for storminess to coincide with general cold.
Below are the teleconnection, teleconnection cases with the best fit for January, and 11-day objective analogs rolled forward two days:
At this time, given the persistence of the EPO- and recent cold east-warm west pattern, I favor a compromise between the kind of pattern depicted on the GFS ensembles and best-fit teleconnection cases and the ECMWF ensembles. That outcome would lead to the following idea:
Western Canada and western third of the U.S.: Warmer to perhaps much warmer than normal, but cold could begin to seep westerward late in the period.
Eastern half of the U.S., except for Florida: Colder than normal. The Great Lakes Region and Ohio Valley could be much colder than normal.
Eastern two-thirds of Canada: Colder than normal.
************************************************************************************************************************************************Posted Wednesday, January 22 @ 8:58 PM
January 22, 2014 saw numerous cities set or tie record low maximum temperatures. Some examples follow.
************************************************************************************************************************************************Posted Wednesday, January 22 @ 2:25 PM
Afternoon thoughts…
1. Today saw more widespread single-digit low temperatures in parts of the East. Washington, DC saw its second such reading this winter. For that city, that is the most since winter 1995-96 when there were also two such low temperatures.
In the Great Lakes region, Detroit had a morning low temperature of -6°. That was Detroit’s 6th such reading, the most since winter 2008-09 when there were also 6 subzero readings.
2. The GFS ensembles are indicating that the a large part of the Great Lakes region, Ohio Valley, and eastward into the Mid-Atlantic and New England States could see cold anomalies of 1.5 standard deviations below normal, with some areas in excess of 2 sigma below normal. The 12z ECMWF is consistent with that idea with potentially even colder readings.
It should be noted that as the current Arctic outbreak drew closer, the ensemble mean anomalies grew colder by 0.5 to 1.0 standard deviations. The recurrence of that outcome would fit what the ECMWF is currently showing.
************************************************************************************************************************************************Posted Wednesday, January 22 @ 10:32 AM
Morning Thoughts on Snowfall:
The recent storm that is now departing New England brought 3.8″ snow to Washington, DC (a city in which some residents seemingly wondered whether it could ever snow there), 13.5″ to Philadelphia, and 11.5″ to New York City. Seasonal snowfall has now reached 33.1″ at Boston, 26.5″ in New York City, and 33.7″ in Philadelphia. In addition, Boston, New York City, and Philadelphia have all received 15″ or more snow this month.
In message #448, I posted revised table of climatological occurrences following December snowfall of 8″ or more snow in Boston, New York City, and Philadelphia in which at least a trace of snow fell during the first half of January. The table confirmed the idea (#359) that the northern Mid-Atlantic region and southern New England area appeared in line for above normal seasonal snowfall. That table is below:
As I have noted in a number of earlier messages, I believe the pattern will likely be conducive to above normal snowfall from the Great Lakes region eastward to the northern Mid-Atlantic and southern New England areas for the January 25-February 15 timeframe. Given the January snowfall data, odds favor above normal February snowfall. Washington, DC should also receive some snowfall and if things work out there were two very snowy cases.
Finally, given where things currently stand, I continue to believe Boston is on track for 50″ or more seasonal snowfall, New York City is on track for 30″ or more snowfall. Philadelphia has already reached 30″ snowfall. Both New York City and Philadelphia have a reasonable shot at 40″ or more seasonal snowfall.
Farther south, Baltimore has received 12.4″ snowfall to date and Dulles International Airport has picked up 16.5″. Seasonal norms for those areas are 20.1″ and 22.0″ respectively. Both locations will probably wind up with above normal snowfall by the time winter is finished.
Washington, DC (DCA) is a more difficult call with respect to reaching its normal figure of 15.4″ given its current figure of 7.2″. Interestingly enough the three cases in which the December-February ENSO Region 3.4 anomaly averaged between -1.0°C and 0.0°C (1934-35, 1960-61, and 1995-96), as appears very likely for winter 2013-14, saw Washington, DC pick up 4.0″, 18.0″, and 20.4″ for the February-March period. The sample size is very small, however, so a lot of caution is required. Therefore, I would use the “dreaded term” of “equal chances” with respect to its prospects of reaching or exceeding its seasonal norm by the end of the winter.
************************************************************************************************************************************************Posted Tuesday, January 21 @ 8:32 AM
ENSO Region 3.4 Cools Some More…
For the week centered around 1/15, ENSO Region 3.4 saw its anomaly decline to -0.7°C. A week earlier, it had been -0.5°C. In contrast, warming continued in Region 1+2, with the anomaly reaching +0.6°C.
************************************************************************************************************************************************Posted Monday, January 20 @ 9:11 AM
With respect to the cold anomalies of 2.0 to 2.5 standard deviations below normal for the Middle Atlantic region, below is a chart showing highs and lows that are 1-3 sigma below normal for the 1/22-25 timeframe:
************************************************************************************************************************************************Posted Monday, January 20 @ 7:23 AM
Snowfall followed by Severe Cold On The Way…
In the near-term, perhaps aided somewhat by the currently negative Arctic Oscillation, a system now looks increasingly likely to produce a moderate snowfall across parts of the Mid-Atlantic and southern New England regions. Parts of Long Island and southeastern New England look to receive the highest accumulations. In those areas, the potential does exist for 6″ or more of powdery snow.
The upcoming cold shot looks formidable. The GFS ensembles now bring cold anomalies to 2.0-2.5 sigma at its height. This likely means that NYC will see its third day this winter with a maximum temperature in the teens and at least 5th or 6th days with lows in the single digits. The MEX MOS already shows lows of 10° during the peak of the cold.
The GFS, which had been prematurely breaking the cold, has now moved into better agreement with the ECMWF and the ECMWF ensembles. This development leads me to believe that my thinking that the Great Lakes Region eastward to the northern Mid-Atlantic and southern New England regions will likely see above normal snowfall during the 1/25-2/15 period has not derailed. Models may vary on a run-to-run basis in terms of identifying specific opportunities, but the pattern has potential. The recent trends with respect to tomorrow’s system offers some evidence of that. That system precedes the snowy period I have outlined and is a sort of bonus. Overall, given December snowfall outcomes, NYC and Philadelphia appear on course for 30″ or more seasonal snowfall and Boston appears on track for 50″ or more seasonal snowfall. In the Midwest, St. Louis appears on track for 30″ or more seasonal snowfall.
************************************************************************************************************************************************Posted Sunday, January 19 @ 9:52 AM
Morning Thoughts…
1. Through mid-February, snowfall events likely will be of the smaller to moderate variety, with locally significant amounts. Given the guidance’s having retreated on an AO- for the extended range, a KU-type snowstorm appears unlikely. This does not mean that there can’t be above normal snowfall. It does limit prospects for excessive snowfall.
2. The AO is the most important teleconnection when it comes to KU snowstorms in February. Since 1950, 78% of such snowstorms commenced when the AO was negative. 50% of February KU snowstorms commenced with an AO-/PNA+ combination.
3. In terms of the MJO, 67% of the February KU snowstorms that occurred since the MJO was recorded, commenced when the MJO is in Phases 7, 8, or 1. None occurred when the MJO was in Phases 4 or 5.
4. At present, there still appears no prospect of a sudden stratospheric warming (SSW) event.
5. A blend of the ECMWF, ECMWF ensembles, GFS, and GFS ensembles suggest that moderation will likely occur to start February. Depending on the evolution of the EPO, the moderation might yield to renewed cold., But that’s too far out for much confidence. For now, the 1/21-23 and 1/26-28 cold shots will assure January closes on a cold note for its final 10 days.
************************************************************************************************************************************************Posted Saturday, January 18 @ 4:32 PM
Cold Pattern Now Evolving…
1. Today saw an area of precipitation bring snow across parts of southeast and central New York State into New England. In areas, qpf was double what had been modeled. For example, both the 1/18 0z and 6z runs of the GFS forecast 0.12″ precipitation for White Plains, NY. The actual amount was 0.27″. The important point is that the guidance can have some difficulties with northern branch disturbances. This is something to keep in mind when dealing with prolonged periods showing almost no meaningful qpf.
2. It is a high confidence idea that the 1/21-23 period will see a strong Arctic shot delivered to the Midwest and East. It won’t be quite as cold as the January 6-7 Arctic shot, but could be cold enough to bring a single-digit low to New York City and some subzero lows in the larger area running from the Midwest to New England.
3. There is a growing probability of another strong Arctic shot around the 1/25-28 timeframe. That Arctic shot might be preceded by a period of snow in parts of the East, as a clipper ushers in the air mass. Were the clipper to have similar dynamics to today’s event, the system could produce a widespread swath of 2″-4″ of snow with locally higher amounts. Details concerning the clipper won’t be pinned down until the middle or even latter part of next week.
4. The European Model hints at another shot of cold to follow closely on the heels of the 1/25-28 cold shot. It may be comparable to the 1/21-23 cold shot. There is some potential it could be a little stronger, but its magnitude is not fully certain. It is also too soon to tell, especially as that idea is not supported by its ensembles. The 12z GFS had a different idea.
Overall, the idea of above normal snowfall from the Great Lakes to northern Mid-Atlantic/southern New England for the January 25-February 15 timeframe still seems reasonable. If one examines the objective analogs from the 1/15 6z GFS and 1/15 0z GFS ensembles, one finds dates close to snowy periods: 1/20/1961, 2/4/2003, 2/12/2006, and 1/22/2009, among others. While the pattern provides no guarantees, it is similar to patterns that have produced in the past.
Finally, the guidance points to the development of a PNA- toward the close of January. However, some recent forecasts toward that end didn’t verify. The pattern evolution might be slower than what the guidance currently shows, especially if historic experience is representative. Since 1950, there were 6 PNA+ ridges that developed in the 1/1-1/20 timeframe and peaked at +1.3 or higher. The median duration was 25 days and the mean duration was 22.7 days. The shortest was 18 days (2009) and the longest was 39 days (1961). The current PNA+ ridge developed January 13, so odds probably favor the PNA’s remaining positive through the rest of January. That outcome would be consistent with the ECMWF, which is slower to bring moderation than the GFS.
************************************************************************************************************************************************Posted Saturday, January 18 @ 7:39 AM
Some morning thoughts…
1. The 1/21-23 cold shot is now a high confidence event. The possibility exists and New York City could have another single-digit low temperature and numerous cities across the Great Lakes into New England could have some subzero lows.
2. The pattern still has potential. However, northern branch disturbances are not always well-modeled very far in advance. The potential has been hinted at in occasional runs showing moderate snowfalls.
3. The 0z GFS aggressively broke the cold after about 240 hours. The 6z GFS has not. More than likely the pattern will ease after the January 26-28 Arctic shot. However, it does not right now look like a very warm period should unfold shortly thereafter.
4. Recently, the SOI reached +50. This is yet another hint that the cooling that has occurred in ENSO Region 3.4 will likely be sustained for some time. In short, February is not likely to see anything close to borderline El Niño conditions and cool ENSO anomalies are probably more likely than warm ones for most or all of the month.
************************************************************************************************************************************************Posted Friday, January 17 @ 8:51 AM
Morning Thoughts…
1. The signal that appeared on yesterday’s operational GFS for a more sustained AO- regime that would persist through January into at least the start of February has been maintained overnight.
Below is a chart that compares the 1/16 and 1/17 6z runs of the GFS (yesterday’s 6z run provided the first strong signal for a more sustained AO-) using the 11-day objective analogs:
2. The strong shot of cold for the 1/21-23 period is a high confidence event.
3. The cold shot will produce a large area of readings 1.5 to 2.0 standard deviations below normal and a smaller area up to 2.5 standard deviations below normal from southern Canada across the Great Lakes Region, Ohio Valley and eastward.
4. The idea that the Great Lakes Region eastward to the northern Mid-Atlantic and southern New England regions will likely see above normal snowfall during the 1/25-2/15 period still looks good given the pattern evolution. Models may vary on a run-to-run basis in terms of identifying specific opportunities, but the pattern has potential.
************************************************************************************************************************************************Posted Thursday, January 16 @ 8:42 AM
Morning thoughts on the longer-range…
If one takes a look at the overnight 1/16 0z and 6z operational GFS runs, one finds both are very cold in the days 7-15 timeframe. Both also feature a strong EPO-. Both also contain a number of analog dates near moderate or larger snowstorms for some parts of the eastern half of North America.
But if one looks more closely, there is actually a rather dramatic change between the 0z and 6z runs. The latter shows the development of meaningful Atlantic blocking to coincide with the strong EPO-. Indeed, if one goes to the 11-day objective analogs from each of these runs, one finds the following:
0z Run:
Average AO: +0.125
AO > 0: 60% of analogs
AO of -1 or below: 30% of analogs
AO of +1 or above: 20% of analogs
6z Run:
Average AO: -1.128
AO < 0: 80% of analogs
AO of -1 or below: 70% of analogs
AO of +1 or above 10% of analogs
If one checks out the GFS ensemble forecast for the AO, one also finds that the many members are now favoring a negative AO in the extended range:
If this forecast verifies and dual Atlantic and Pacific blocking develop, that would increase prospects for a cold February in the eastern third to half of the CONUS, along with southern Ontario and Quebec. The latter cold anomalies would depend on the magnitude of blocking. If the blocking becomes too strong, then the cold anomalies could be driven southward.
Such dual blocking would also allow for potentially more opportunities for larger snowfalls. The Great Lakes region, northern Mid-Atlantic (e.g., Philadelphia) and southern New England areas remain on track for above normal seasonal snowfall, as the December outcomes were consistent with such seasons. The pattern ahead looks promising, particularly for the 1/25-2/15 period. If blocking develops, things could also become more favorable further south in the Mid-Atlantic region, including the Baltimore and Washington, DC areas.
The takeaway is that the theme of a growing probability of a cold outcome in parts of the eastern CONUS has been sustained in the overnight guidance. In fact, even as it is still outside its skillful range, the CFSv2 has recently shifted from featuring widespread February warmth to an increasingly colder idea for the eastern third to half of North America.
This post has been promoted to an article
************************************************************************************************************************************************Posted Wednesday, January 15 @ 10:19 AM
Morning thoughts…
1. No changes about the coming cold for the last week of January.
2. The GFS ensembles and reforecast ensembles both agree that the EPO ridge (EPO-) will be building as January comes to a close. This could have implications for February.
3. The idea of above normal snowfall from the Great Lakes to northern Mid-Atlantic/southern New England for the January 25-February 15 timeframe still seems reasonable. If one examines the objective analogs from the 1/15 6z GFS and 1/15 0z GFS ensembles, one finds dates close to snowy periods: 1/20/1961, 2/4/2003, 2/12/2006, and 1/22/2009, among others. While the pattern provides no guarantees, it is similar to patterns that have produced in the past.
4. The guidance points to the development of a PNA- toward the close of January. However, some recent forecasts toward that end didn’t verify. The pattern evolution might be slower than what the guidance currently shows.
5. Despite some Internet rumors, there still appears to be no high risk of a sudden stratospheric warming through at least the next 10 days. There are some indications of a smaller warming event, but right now the guidance does not show the event reaching the threshold of a sudden or major stratospheric warming event, much less propagating downward. This minor warming might well be a reflection of the recent blocking that has been occurring.
************************************************************************************************************************************************Posted Tuesday, January 14 @ 3:56 PM
For those who are interested, below are the 500 mb height anomaly and surface temperature anomaly maps based on the 11-day objective analogs from the 1/13 18z, 1/14 0z, 1/14 6z, and 1/14 12z runs of the GFS:
************************************************************************************************************************************************
Posted Tuesday, January 14 @ 12:11 PM
The latest EPO forecast shows the EPO reaching approximately 200 meters below normal toward the end of January. During the 1981-10 climate base period, there were 3 cases in which the EPO fell to 200 or more meters below normal in the January 20-31 period during which January had temperature anomalies similar to what has occurred so far this month: 1994, 2003, and 2010.
All featured a lot of cold in February in a large part of eastern North America. Two of those three cases (1994 and 2010) featured above to much above February snowfall from Chicago eastward to the northern Mid-Atlantic and southern New England areas (a larger part of the Mid-Atlantic saw above normal snowfall in 2003 and 2010 then 1994). In short, the latest guidance concerning the EPO adds to my growing confidence that areas (Great Lakes, Ohio Valley, northern Mid-Atlantic, and southern New England) could see above normal snowfall during the January 25-February 15 period.
************************************************************************************************************************************************
Posted Tuesday, January 14 @ 12:11 PM
The latest EPO forecast shows the EPO reaching approximately 200 meters below normal toward the end of January. During the 1981-10 climate base period, there were 3 cases in which the EPO fell to 200 or more meters below normal in the January 20-31 period during which January had temperature anomalies similar to what has occurred so far this month: 1994, 2003, and 2010.
All featured a lot of cold in February in a large part of eastern North America. Two of those three cases (1994 and 2010) featured above to much above February snowfall from Chicago eastward to the northern Mid-Atlantic and southern New England areas (a larger part of the Mid-Atlantic saw above normal snowfall in 2003 and 2010 then 1994). In short, the latest guidance concerning the EPO adds to my growing confidence that areas (Great Lakes, Ohio Valley, northern Mid-Atlantic, and southern New England) could see above normal snowfall during the January 25-February 15 period.
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Posted Tuesday, January 14 @ 10:13 AM
Some morning thoughts…
1. The probability of a return to severe cold during the latter half of the 1/24-31 period is increasing. The GFS ensembles now show widespread 1 standard deviation or greater cold anomalies for the 1/27-30 period. The 1/14 6z run of the operational GFS featured extreme cold for that timeframe across a large part of the eastern CONUS.
2. The GFS ensembles, reforecast ensembles, and ECMWF ensembles all show much below normal height anomalies across southern Ontario and southern Quebec, not far from the U.S. border for that period.
3. Prior to then, the operational ECMWF has a fairly strong, but not really severe, cold shot for the 1/21-23 period.
4. The West will likely remain warmer than normal courtesy of the PNA+, which may only erode slowly through the rest of this month.
5. Despite the recent rather sharp cooling of ENSO Region 3.4 (currently -0.5°C anomalies), the warming in Region 1+2 at this point in time has sometimes been an indicator of the development of an El Niño during the following fall or winter. Examples include 1986, 2006, and 2009 (winters 1986-87, 2006-07, and 2009-10 featured El Niño conditions). From this far out, it’s really tough to have any degree of confidence.
By later in the spring, the statistical models might provide a better indication. They have done quite well the past several years, so that’s where one should be looking for emergent ENSO trends.
When it comes to the dynamical models, for the past several years, they have demonstrated much less skill relative to the statistical models. Hence, a large dose of caution is required when looking at the dynamical ENSO models, especially when one goes out more than 6 months into the future. For example, last summer, even when ENSO Region 1+2 remained very cool–historically an almost “slam dunk” indication that there would be no wintertime El Niño–25% of the dynamical models were still forecasting an El Niño. Currently, for the third consecutive winter, they are forecasting the development of an El Niño for the following winter.
So far, they are 0-2 in their last two cases, but the historical data suggests that they might fare a little better for winter 2014-15. The statistical models were less keen on an El Niño for the last two winters and are borderline for 2014-15. The performance gap between the dynamical models and statistical ones suggests that understanding of ENSO is still not sufficiently robust for long-term forecasting of ENSO. What is more certain is that there will be no weak El Niño conditions or borderline El Niño conditions through the remainder of meteorological winter and probably spring, as well.
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Posted Monday, January 13 @ 12:06 PM
January 24-31, 2014 Thoughts…
By the time the last week of January rolls around, the thaw that sent temperatures well into the 50s as far as Boston will be a fading memory. Instead, cold anomalies that will have returned ahead of the month’s closing week will prevail. There is a growing likelihood that a bout of severe cold could occur at some point during this timeframe, especially as the EPO ridge that predominated through December into the opening days of January returns.
The second aspect is that the pattern appears increasingly likely to become snowier from the Great Lakes region eastward to the northern Middle Atlantic and southern New England areas. Both among the teleconnection cases and GFS ensemble’s objective analogs in recent days, one finds a number of dates that were fairly close to moderate or sizable snowfalls. Those dates have included late January 1961, late January 2003, and just after mid-January 2005. In short, it increasingly appears that the pattern evolution should result in the above-noted areas seeing above normal snowfall for the January 25 through February 15 period.
Below are charts showing the latest ensemble forecast for the EPO, teleconnection cases, combined teleconnection and objective analog cases for which January anomalies were similar to those of the current month to date, and the reforecast ensemble mean 850 mb anomalies:
Based on the above charts, I expect the eastern half of the CONUS and Canada to have colder to potentially much colder than normal readings for the last week of January. Even Florida, where winter has been largely absent, will likely wind up with below normal readings for the period as a whole. The western half of the CONUS and Canada should be warmer to possibly much warmer than normal courtesy of the PNA ridge.
Should severe cold return to the Great Lakes, Ohio Valley, Mid-Atlantic, and New England areas, that outcome would fit past winters that featured severe cold during the first half of January. Using New York City to illustrate the return of severe cold,
during the 1981-2010 climate base period, there were 5 cases when the low temperature in New York City fell 2 or more standard deviations below the January average on at least one day during the first half of January. The January 7, 2014 low temperature was 2.242 standard deviations below the January 1981-2010 average low temperature.
The lowest temperatures on or after 1/25 for those cases were as follows:
1981: 8°, 2/5
1982: 9°, 1/27
1988: 9°, 2/7
1996: 5°, 2/5
2004: 7°, 1/25
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Posted Monday, January 13 @ 9:30 AM
Some morning thoughts…
1. ENSO Region 3.4 has continued to cool. In fact, for the week centered around January 8, the ENSO Region 3.4 anomaly was -0.5°C. This cooling, which is in line with the superior-performing statistical ENSO models that had all but ruled out even borderline El Niño conditions toward the end of meteorological winter all but eliminates that prospect.
2. The ENSO developments will have implications for February. Odds of a colder than normal February across the CONUS, particularly the northern tier have increased. In contrast, had ENSO been shifting toward borderline El Niño conditions, one might have seen less cold during February, except across the southern CONUS where a more active subtropical jet resulted in greater precipitation and lower overall readings.
3. The ensembles are now showing the return of a familiar “friend” this winter–the EPO ridge. This development also increases the probability that January will finish colder than normal and February could start colder than normal.
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Posted Sunday, January 12 @ 9:01 AM
Some morning thoughts…
1. The recent warmth was well-modeled. In Boston, Caribou, Concord, New York City, and Portland, readings all peaked 1.5 to 2.5 standard deviations above normal. This morning’s high temperatures of 44° in Caribou and 51° in Portland were the 2nd and 3rd warmest readings on record for 1/12 in those cities.
2. Similar magnitude warmth could occur across northern New England into parts of Quebec tomorrow.
3. In the longer range, there are some indications on the guidance that the EPO, which has been positive 9 of the last 15 days, could again go to negative. However, the AO could return to positive values. The PNA could remain generally positive.
Such a pattern could result in cooler readings in the eastern third to half of the U.S., excepting Florida and perhaps the Gulf Coast, in the upcoming week and perhaps the last week of the month, as well. Some guidance suggests a bout of severe cold similar to the beginning of December and beginning of January, but there’s enough uncertainty to be cautious about that idea. Regardless, snowfall prospect for the Great Lakes out to the northern Mid-Atlantic and southern New England regions could increase. Those areas have already enjoyed above normal snowfall to date and they appear to remain on course for a snowy winter.
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Posted Friday, January 10 @ 3:10 PM
January 11-12, 2014 Warm Shot…
The GFS ensembles continue to point to a brief push of very warm air into New England tomorrow and into Sunday morning in northern New England. The GFS ensembles show a large area of temperatures of 1.5-2.0 standard deviations or more above normal and a small area of 2.5 standard deviations above normal. This would equate to readings reaching well into the 50s and perhaps just above 60° in southern New England and 40s to perhaps low 50s in some parts of northern New England.
This very warm weather, with perhaps a second shot early next week, will likely be short-lived.
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Posted Tuesday, January 7 @ 12:10 AM
Just before midnight, the lowest temperatures for January 6 included:
Atlanta: 12° (coldest since 1/16/2009 when the temperature fell to 12°)
Baltimore: 8° (coldest since 1/4/2014 when the temperature fell to 6°)
Birmingham: 13° (coldest since 1/16/2009 when the temperature fell to 12°)
Chicago: -16° (broke daily record of -14° from 1884 & 1988; coldest since 1/16/2009
when the temperature fell to -18°)
Cincinnati: -5° (coldest since 1/22/2011 when the temperature fell to -8°)
Cleveland: -11° (broke daily record of -9° from 1884; coldest since 1/16/2009 when the
temperature fell to -13°)
Columbus: -7° (coldest since 1/17/2009 when the temperature fell to -11°)
Dayton: -10° (broke daily record of -8° from 1924; coldest since 1/16/2009 when the
temperature fell to -14°)
Des Moines: -12° (coldest since 12/24/2013 when the temperature fell to -14°)
Detroit: -14° (broke daily record of -7° from 1924; coldest since 1/16/2009 when the
temperature fell to -15°)
Harrisburg: 6° (coldest since 1/5/2014 when the temperature fell to 6°)
Houston: 27° (coldest since 2/11/2011 when the temperature fell to 24°)
Indianapolis: -15° (coldest since 1/21/1994 when the temperature fell to -16°)
Kansas City: -11° (coldest since 2/3/2011 when the temperature fell to -12°)
Little Rock: 12° (coldest since 2/11/2011 when the temperature fell to 10°)
Louisville: -3° (coldest since 1/31/2004 when the temperature fell to -5°)
Minneapolis-St Paul: -23° (coldest since 1/30/2004 when the temperature fell to -24°)
Nashville: 4° (coldest since 1/24/2003 when the temperature fell to 2°)
New Orleans: 28° (coldest since 1/14/2011 when the temperature fell to 28°)
Pittsburgh: -7° (broke daily record of -5° from 1942; coldest since 1/17/2009 when the
temperature fell to -10°)
Savannah: 27° (coldest since 2/18/2013 when the temperature fell to 26°)
St. Louis: -8° (coldest since 2/3/1996 when the temperature fell to -12°)
Toledo: -15° (broke daily record of -14° from 1884; coldest since 1/19/1994 when the
temperature fell to -18°)
Washington, DC: 12° (coldest since 1/17/2009 when the temperature fell to 8°)
Low Maximum Temperatures:
Chicago: -2° (broke daily record of -1° from 1912; coldest since 2/3/1996 when the high
temperature was -5°)
Houston: 36° (broke daily record of 38° from 1971; coldest since 2/4/2011 when the high
Temperature was 31°)
Louisville: 19° (lowest since 1/8/2010 when the high temperature was 19°)
Minneapolis-St. Paul: -12° (lowest since 2/2/1996 when the high temperature was -17°)
New Orleans: 40° (broke daily record of 46° from 1972; coldest since 2/3/2011 when the
High temperature was 39°)
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Posted Monday, January 6 @ 7:09 PM
New Daily Low Maximum Temperatures:
Houston: 36° (broke the daily record of 38° set in 1971 and was the coldest high temperature since 2/4/2011 when the temperature only reached 31°)
New Orleans: 40° (broke the daily record of 46° set in 1972 and was the coldest high temperature since 2/11/2011 when the temperature only reached 39°)
Also, at 7 pm, Detroit’s temperature had fallen to -10°. That has broken the daily record low temperature of -7°, which was set in 1924. The temperature is also Detroit’s coldest reading since 1/17/2009 when the mercury fell to -11°.
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Posted Monday, January 6 @ 5:10 PM
1/6-8/2014 Cold Shot Update…
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Posted Monday, January 6 @ 1:37 PM
At 18z, temperatures were running somewhat below MOS in the Great Lakes and western portions of the Ohio Valley. Elsewhere, readings were generally running above the MOS projections (12z MOS guidance):
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Posted Monday, January 6 @ 10:10 AM
Brief update on the 1/6-8 Cold Shot…
Daily low temperatures for 1/6 through 10 am:
Chicago: -16° (New daily record low; old record: -14° 1884 and 1988)
Indianapolis: -14° (Coldest reading since 1/21/1994 when the temperature fell to -16°)
Louisville: 0° (Coldest reading since 1/16/2009 when the temperature fell to -1°)
Nashville: 6° (Coldest reading since 1/16/2009 when the temperature fell to 5°; Taylor Swift won’t sing about today’s weather)
St. Louis: -7° (Coldest reading since 2/3/1996 when the temperature fell to -12°)
Very likely daily record low maximum readings:
Houston: Current record: 38°, 1971
Little Rock: Current record: 22°, 1984
New Orleans: Current record: 46°, 1972
Likely daily record low maximum reading:
Minneapolis-St. Paul: Current record: -14°, 1909
Possible daily record low maximum reading:
Chicago: Dependent on the readings just after midnight: Current record: -1°, 1912
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Posted Sunday, January 5 @ 7:28 PM
Some evening thoughts…
1. At Green Bay, while the 49ers and Packers struggle on Lambeau Field’s frozen tundra, the temperature is also struggling to catch up with the MOS projections. At 6 pm CST, the temperature was 4° vs. the 1° GFS MOS forecast for 0z. Nevertheless, the coldest air mass in at least a number of winters, possibly back to the 1990s is now moving into the region.
2. At St Louis, a large snowstorm will wind down tonight after dumping 6″-12″ snow. Subzero cold will follow.
3. In the longer-range, a pattern relaxation is likely to unfold. The period of moderation could last 7-10 days. However, teleconnection cases and the extended range of the GFS are pointing to a return of the cold afterward. Whether or not the cold is as severe as has been the case at the opening of January remains to be seen, but the cold should be sufficient to produce snowfall opportunities in a large area running from the Midwest eastward. Some of the 11-day objective analogs e.g., 1/11/1994, are quite bullish on the return of significant cold.
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Posted Saturday, January 4 @ 10:18 PM
Super Cold Shot for 1/5-8/2014…
The GFS ensembles are now indicating 850 mb temperature anomalies of 4 standard deviations below normal in parts of the Midwest/Great Lakes/Ohio Valley region from the upcoming cold air mass. On the table would be the idea that both St. Louis and Chicago could see subzero high temperatures and low temperatures of perhaps -15° in St. Louis and below -20° in Chicago.
The three lowest maximum temperatures for St. Louis are:
1. -5°, 12/24/1983
2. -4°, 12/29/1880
3. -3° 2/9/1899 and 2/12/1899
The three lowest minimum temperatures for St. Louis are:
1. -22°, 1/5/1884
2. -19°, 1/18/1930
3. -18°, 2/13/1905 and 1/20/1985
The three lowest maximum temperatures for Chicago are:
1. -11°, 12/24/1983 and 1/18/1994
2. -10° 1/25/1897
3. -8°, 2/9/1899
The three lowest minimum temperatures for Chicago are:
1. -27°, 1/20/1985
2. -26°, 1/10/1982
3. -25°, 1/16/1982 and 12/24/1983
The latest MOS figures for lowest temperature (18z GFS) are:
Chicago: -22°
St. Louis: -14°
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Posted Saturday, January 4 @ 1:06 PM
The recent snowstorm that brought 9.0″ snow to Philadelphia, 6.4″ to New York City, and 15.1″ to Boston has brought seasonal totals to 20.2″ in Philadelphia, 15.0″ in New York City, and 26.8″ in Boston. Snowy winters have often seen a snowy December followed by additional snowfall within the first 10 days of January.
Taking the cases provided in #359 in this thread for which Philadelphia, New York City, and Boston each received 8″ or more snowfall in December and refining them for cases in which at least a trace of snow fell in all three cities in the January 1-10 period, the idea of a snowy winter is maintained.
At this point in time, it appears very likely that Philadelphia and New York City will see 30″ or more snowfall this winter and Boston will see 50″ or more. In short the thaw that will unfold beginning later next week will not mark the end of winter so to speak.
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Posted Saturday, January 4 @ 8:33 AM
This morning saw numerous cities in the Mid-Atlantic and New England areas record their lowest temperatures in recent winters. Some highlights:
Albany: -12° (lowest since 1/24/2011 when the temperature fell to -13°)
Allentown: -4° (lowest since 1/24/2011 when the temperature fell to -4°)
Atlantic City: -3° (lowest since 2/6/1996 when the temperature fell to -3°)
Baltimore: 6° (lowest since 1/17/2009 when the temperature fell to 2°)
Boston: 2° (lowest since yesterday when the temperature fell to 2°; yesterday was the coldest since 1/24/2011 when a low of -2° occurred)
Bridgeport: 3° (lowest since 1/24/2011 when the temperature fell to 0°)
Burlington: -15° (lowest since 1/24/2011 when the temperature fell to -19°)
Concord: -17° (lowest since 1/16/2009 when the temperature fell to -24°)
Danbury: -7° (lowest since 1/24/2011 when the temperature fell to -12°)
Harrisburg: 5° (lowest since 1/24/2011 when the temperature fell to 3°)
Hartford: -9° (lowest since 2/5/1996 when the temperature fell to -13°)
Islip: 0° (lowest since 1/15/1988 when the temperature fell to -7°)
New Haven: 2° (lowest since 1/24/2011 when the temperature fell to -2°)
New York City: 8° (lowest since 1/24/2011 when the temperature fell to 6°)
Newark: 6° (lowest since 1/24/2011 when the temperature fell to 5°)
Philadelphia: 8° (lowest since 1/24/2011 when the temperature fell to 8°)
Portland: -14° (lowest since 1/16/2009 when the temperature fell to -16°)
Providence: -3° (lowest since 1/16/2004 when the temperature fell to -6°)
Westhampton: -13° (lowest since 1/17/2009 when the temperature fell to -15°)
White Plains: 0° (lowest since 1/24/2011 when the temperature fell to -1°)
Wilmington, DE: 5° (lowest since 1/17/2009 when the temperature fell to 5°)
Worcester: -4° (lowest since 1/24/2011 when the temperature fell to -9°)
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Posted Friday, January 3 @ 7:38 PM
Today saw numerous cities in the Northeast post their lowest high temperatures in several winters. Highlights included:
Albany: 5° (lowest since 1/24/2011 when the temperature only reached 5°)
Allentown: 15° (lowest since 1/16/2009 when the temperature only reached 13°)
Boston: 14° (lowest since 1/24/2011 when the temperature only reached 13°)
Bridgeport: 14° (lowest since 1/15/2004 when the temperature only reached 13°)
Burlington: -3° (lowest since 1/21/2005 when the temperature only reached -3°)
Concord: 7° (lowest since 1/24/2011 when the temperature only reached 6°)
Hartford: 12° (lowest since 1/18/2005 when the temperature only reached 11°)
Islip: 18° (lowest since 1/16/2009 when the temperature only reached 17°)
New York City: 18° (lowest since 1/16/2009 when the temperature only reached 16°)
Newark: 17° (lowest since 1/18/2005 when the temperature only reached 17°)
Providence: 17° (lowest since 1/23/2013 when the temperature only reached 16°)
White Plains: 14° (lowest since 1/27/2005 when the temperature only reached 12°)
Worcester: 9° (lowest since 1/24/2011 when the temperature only reached 8°)
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Posted Friday, January 3 @ 2:11 PM
Already, one has seen some impressive cold temperatures today. For parts of the East, tonight and tomorrow morning will likely see the coldest readings so far. For some of those cities, this might be the winter’s coldest air mass. In the Great Lakes region and Ohio Valley, an even colder air mass is likely to produce extreme readings early next week.
For today, some highlights:
Boston: 2° (coldest reading since 1/24/2011 when the temperature fell to -2°)
Chicago: -12° (coldest reading since 1/16/2009 when the temperature fell to -19°)
Columbus: 1° (coldest reading since 1/22/2011 when the temperature fell to -2°)
Detroit: -5° (coldest reading since 2/10/2011 when the temperature fell to -5°)
Harrisburg: 10° (coldest reading since 2/11/2011 when the temperature fell to 9°)
Indianapolis: -3° (coldest reading since 1/21/2011 when the temperature fell to -3°)
New York City: 10° (coldest reading since 1/24/2011 when the temperature fell to 6°)
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Posted Thursday, January 2 @ 11:13 AM
Severe Great Lakes/Ohio Valley Cold Shot of January 5-8, 2014:
A significant winter storm will bring 4″-8″ of snow across the northern Mid-Atlantic, 6″-12″ across parts of Long Island, and 8″-16″ across parts of southern New England today and tomorrow. It will also pull down cold air that will likely result in the coldest minimum and maximum temperatures in several years in parts of that region.
Afterward, the big focus will be the potential super cold air mass that the ECMWF and to a lesser extent the GFS has been suggesting could impac an area from the Great Lakes region to the Middle Atlantic states in the January 5-8 timeframe. The coldest anomalies relative to normal are forecast to occur in the Great Lakes Region and Ohio Valley.
The latest GFS ensembles show an area of cold 2-3 standard deviations below normal. If that verifies, some parts of the Great Lakes region and Ohio Valley could see their coldest readings since 1994. The likely absence of snow cover will likely modify the air mass farther south and east, with the big cities of the Middle Atlantic region likely have cold in the 1.5 to 2.5 sigma range. However, should the precipitation end with a period of snow sufficient to cover the ground, somewhat colder readings would be possible.
Below are tables showing the GFS ensemble mean 850 mb anomalies forecast for January 7 0z and low temperatures associated with the standardized anomalies for select cities:
In terms of the coldest readings forecast for the 1/5-8 timeframe, the 1/2/2014 0z run of the ECMWF has forecast a low temperature of -20° in Chicago, -18° in Columbus, and -19° in Indianapolis. The 1/2 0z MEX MOS output for lowest temperatures for those three cities is -12°, -11°, and -15° respectively.
The last time the temperature fell to -10° or below in Chicago was January 16, 2009 (-18°). The last time the temperature fell to -10° or below in Columbus was January 17, 2009 (-11°). The last time the temperature fell to -10° or below in Indianapolis was January 16, 2009 (-12°).
The last time the temperature fell to -15° or below in Chicago was January 16, 2009 (-18°). The last time the temperature fell to -15° or below in Columbus was January 21, 1994 (-15°). The last time the temperature fell to -15° or below in Indianapolis was January 21, 1994 (-16°).
Finally, for perspective, the three coldest readings on record for select cities are below:
Chicago:
-27°, January 20, 1985
-26°, January 10, 1982
-25°, January 16, 1982 and December 24, 1983
Columbus:
-22°, January 19, 1994
-19°, January 17, 1977 and January 20, 1985
-17°, December 22, 1989 and January 18, 1994
Indianapolis:
-27°, January 19, 1994
-25°, January 5, 1884
-23°, December 22, 1989