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Posted: (April 22, 2008 06:35 pm)
It sure has been an active week weather-wise with impressive rainfall amounts over Southern PA, MD, VA, into NC associated with a very slow moving upper-air disturbance cut off from the mean flow. A chilly month of April has continued in the Pac NW and the warmth over the Gulf Coast is the real deal. Looking ahead, a very pleasant ridge of high pressure will dominate the east coast through end of the workweek, while a backdoor cold front will knock temperatures below normal in New England by Thursday. Trough in the Pac NW is finally going to respond to a negative pulse in the Eastern Pacific Oscillation and kick out, deepen, and cut off over the Eastern US this early next week. Here is an impressive model interpretation of how this is going to happen:
This is the 12z ECMWF 500mb forecast for 168h valid next Tuesday morning. This is the hot model and has been consistent with this scenario. But as you can see, another trough is aimed at the Pac NW by this time and the EPO has flipped to positive, as you can see by the high located between Hawaii and Baja California. This indicates that the cold period is going to be relatively short-lived. However there is a possibility that blocking prevents the cut off low from lifting out and the new trough simply buckles in underneath, but given the time of year, that is not likely. Later this week I will update this and go into some more detail. Also, next week I will issue a forecast for the month of May.
