(Blog Written by Donald Sutherland)
July 24-31, 2012 Thoughts:
The GFS ensembles continue to suggest that the PNA could go strongly negative prior to the start of this period (values -1.00 or below). At the same time, the development of a possible El Niño event continues albeit on a gradual basis. As a result, one could continue to see widespread warmth (with some exceptions) across North America to close July.
The chart below shows the composite temperature anomalies for ENSO Region 3.4 anomalies of +0.20°C to +0.80°C, a PNA of -1.50 to -0.50, and an AO of -0.25 to +0.50 for North America.
The NAEFS for the July 22-28 timeframe shows a probability of warm anomalies across virtually all of North America, except Texas, New Mexico, Colorado, and part of the West Coast. Some of the ensemble guidance suggests that the Arctic region could see readings become closer to normal toward and during the last week of July and perhaps even somewhat cooler than normal in areas. Should such a regime develop and persist, it could have implications down the road, particularly as August evolves.
Taking into consideration the upstream conditions, teleconnection analogs, ensemble guidance, and decadal trends, I expect the following for the July 24-31 timeframe:
– Warmer than normal across most or all of Canada
– Near to perhaps somewhat cooler than normal across Texas
– Cooler than normal in the Pacific Northwest
– Warmer than normal across the rest of the U.S.
Given some of the analogs that are in the mix and pattern repetition over the past 6 months, one cannot rule out the possibility of some much above normal readings in parts of the Central Plains, Great Lakes (U.S. and Canada), and Eastern U.S. during a portion of the July 24-31 period.