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Posted: (April 17, 2008 11:00 pm)
We certainly have an interesting pattern developing over the next couple of weeks that in some ways looks to continue a trend that I expected for the month of April, but in other ways does not. The following image is from the PSU E-Wall which has a lot of great weather info on it. The left image is the 8-10 day ECMWF 500mb heights and anomaly, and the right image is the same but for the GFS:
One thing to notice is the stark disagreement over the central North American continent. I tend to lean slightly toward the GFS here, as the ECMWF, although better in general than the GFS, has not done well over the last couple of months, and has been inconsistent in the long range period. A couple places where the models agree are continuing warmth over the Gulf Coast, which was expected. Also, an active pattern is expected to continue over the Pac NW and the Northern Plains. This, too, was also expected for the month. However, a few things that have yet to develop are a trough over the NE US. As warm as the ECMWF may seem over the eastern US, it is important to keep in mind that surface highs can keep an easterly flow and below normal daytime highs underneath positive 500mb anomalies.
So in summary: highest confidence areas are warmth over the Gulf Coast, active periods of cold weather over the Pac NW into the Northern Plains. Lower confidence areas are elsewhere, but look for chilly weather to make a comeback into the eastern US by month's end and warmth to build over the SW and Southern Plains.
