May 31

Philadelphia Area Weather Threat Assessment Forecast (6/1 – 6/15/15)

Good Evening Everyone,

At least, finally got a new package put together.  I made some format changes and you’ll see that below. I definitely don’t want to get into all the model guidance detail, but address in a higher level. Still, if there is some very interesting items to mention, I’ll sure do that below.  The one thing that we may finally see is a change in the weather pattern that become more favorable for some much needed rainfall.  The next two weeks look more favorable for a wetter pattern, but may include some severe weather.  The key over the next two weeks and whether the region may be in a bigger drought is that if we don’t get the wet weather.  Quite a few locations are running 2 to 4 inches behind, especially over Eastern PA.  One of the bigger drivers in the weather pattern is El Nino.  Right now, its in the moderate category and forecast to go strong.  It maybe one of the reasons that we’ve been so dry of late.  For now, let’s see how things play out over the next few weeks.  

 

 

For official outlooks, please check out the following links
– NWS Daily Weather Briefing
– NWS Mount Holly NJ Facebook
– NWS Mount Holly, NJ Twitter

 

Weather Threat Assessment Forecast
Monday, June 1st through Monday, June 15th

Southeastern Pennsylvania, Southern New Jersey, Northeast Maryland,
and Northern Delaware

Issued Sunday Evening, May 31st   

 

 

5 Day Forecast Period
Monday, June 1st through Friday, June 5th 

 

Weather Threat Forecast Tables
(Click on the hyperlinks below to access the images below) 

Note: Table Legend: Forecaster Confidence Level, Severity Event Index: Minor, Significant, Major, Extreme

 

Forecast Discussion

  • Basic Pattern Overview
    • The model ensemble trends of the last several days favors an upper air pattern of a trough over the Western US Coast. Ridging is favored over the central US.  A trough will be over the Eastern US.  This will mean the jet stream will be nearby to allow some active weather for this period. The good news is that some rain is finally in the forecast, but we may get too much in a short period of time.  This means some excessive rainfall and severe weather possible early this period.  
  • Weather Threats
    • There are two weather threats possible.  
      • On Monday, excessive rainfall and severe weather is possible.  A cold front will slowly move through the region.  This front will be the trigger for showers and thunderstorms. Any thunderstorms that do develop will have the potential to produce very heavy rainfall, which may cause some flooding.  Rainfall rates per hour may reach 2 inches, perhaps even high in a few locations.  This type of rainfall rate can cause some significant flooding.  Even though the region hasn’t gotten much rain, you can still get flooding from intense rainfall, because the water doesn’t have the time to runoff.  My confidence level on this threat is high.  For the severe weather threat, there may be a few thunderstorms that may contain damaging winds and large hail.  The coverage for severe weather will not be widespread.  My confidence on this threat is low due to the lack of sunshine. Monday will be cooler and with more clouds and cooler temperatures, that should limit severe weather threat.  
      • For Tuesday, excessive rainfall is still possible. Showers and thunderstorms will still be possible and again they may produce very heavy rainfall, which could result in some flooding. Once the cold front passes through the area, the weather threat will be over.  
  • Weather Ensemble Forecast Maps (Click on the hyperlinks below to access maps)

 

6 to 10 Day Forecast Period
Saturday, June 6th through Wednesday, June 10th

 

Weather Threat Forecast Tables 
(Click on the hyperlinks below to access the images below) 

Note: Table Legend: Forecaster Confidence Level, Severity Event Index: Minor, Significant, Major, Extreme

 

Forecast Discussion

  • Basic Pattern Overview
    • The model ensemble trends of the last several days favors strong ridging over the Pacific Northwest with a trough over the Southwest US.  Then some ridging is forecast to develop over Central Canada, while a trough will be over the Eastern US.  This type of upper air pattern favors an unsettled forecast period.  This pattern may mean may warmer than average temperatures, increased humidity with some of the active weather similar to what the Central US south to Texas has been dealing with the past several weeks.  One of the key things to watch is how much precipitation actually falls over the area.
  • Weather Threats
    • This forecast period favors two weather threats. They include excessive rainfall and severe weather and the two may be significant.  My forecaster confidence level is medium. One of the key players in figuring out weather threats is the position of the jet stream.  From what I can gather after looking at the model guidance, it will to our west.  This location of where the jet stream will setup, will allow for active weather.  Another interesting item that provides clues on our active weather was what from the European model ensembles showed, which was a bubble of very warm air forecasted to be over the central US.  This heat will collide with some cooler air thats forecasted to be over the Great Lakes.  We may be in a corridor where a front is position in a way to act as the trigger for the active weather.  Typically as we head into June and even July, we tend to be get hit with severe weather.  For now, its a forecast period that needs to be monitored.  
  • Weather Ensemble Maps: Click on the hyperlinks below to access maps

 

11 to 15 Day Period
Thursday, June 11th through Monday, June 15th 

 

Weather Threat Forecast Tables
(Click on the hyperlinks below to access the images below)

 

Forecast Discussion

  • Basic Pattern Overview
    • The model ensembles show some upper level ridging over the Western US and continues to the Central US.  Then more of trough that continues to develop over the Eastern US.  This type of setup may mean a continuation of active weather, which means some excessive rainfall and even some severe weather.
  • Weather Threats
    • For this period, I’m forecasting some severe weather and even excessive rainfall.  Right now my confidence level is medium.  Like the 6 to 10 day forecast period, I still think this can be an active period.  So, this will need to be monitored and see if this is the case.  
  • Weather Ensemble Maps: Click on the hyperlinks below to access maps

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Background Information

  • I am very excited to provide a new forecast product for the Philadelphia Area, which includes Southeastern Pennsylvania, South Jersey, northeastern Maryland, and Delaware.  In here will be a new experimental product that I’ve produced for the Philadelphia Area.  
  • Right now, I like to issue this product once a week, especially on Sundays. If time permits, I’ll issue a new forecast during the week. 
  • This forecast will aide pretty much everyone from Public, Emergency Management, SKYWARN, and RACES. The idea is to provide everyone with a forecast that gives them the needed lead time to prepare for significant hazardous.
  • Finally, below is further background on my forecast tables and geographic locations
    • Table Legend
    • Forecast Geographic Locations
      • Southeast Pennsylvania: Chester, Montgomery, Bucks, Delaware, and Philadelphia
      • South Jersey: Burlington, Ocean, Camden, Gloucester, Salem, Cumberland, Atlantic, Cape May
      • Northeastern Maryland: Cecil, Kent, Queen Anne’s, Caroline, and Talbot
      • Delaware: New Castle, Kent, and Sussex