Forecast for Sunday, May 8, 2011

Showers and thunderstorms have developed across mainly the northwestern portions of the region this afternoon. These showers and thunderstorms are developing in response to a trough of low pressure swinging through our region, acting as a triggering mechanism. The latest satellite imagery is showing increasing cumulus cloud development in eastern areas and additional showers and thunderstorms could develop shortly elsewhere. Colder air aloft may allow for any thunderstorm to yield some small hailstones. In addition, recent observations around Allentown and Reading suggest that some gusty winds are occurring with the scattered thunderstorms. Gusts to 40 MPH seem reasonable with any thunderstorm or perhaps a notch higher.

Another trough of low pressure will focus itself across Baltimore and Washington on Sunday, before sliding east-southeast. This system could create some showers and possibly thunderstorms in primarily the southern portions of our forecast area. Elsewhere, more afternoon and evening cumulus clouds could form with afternoon heating. An isolated shower cannot be ruled out in Philadelphia, although the chance is greatest south of Philadelphia.

High pressure takes over on Monday and holds firm through Wednesday. During this timeframe, a low pressure area will form off the New England coastline. Our region could be caught up in a wind tunnel and therefore some breezy conditions are likely during this time. It will not be the sunniest period as some clouds will likely bubble up with afternoon heating. I see signs that the high pressure area begins to nudge eastward and breakdown as the new weekend arrives and this perhaps could allow for some triggering mechanisms to begin to impact the area with showers and thunderstorms.

I see our ESNO phase turning more neutral as we head into the summer months. This introduces the possibility for less in the way of shear in the Atlantic Ocean. Of course, other factors are needed for tropical development, but this trend is worth mentioning this early in the game. Rarely do we go two years without a U.S. land falling hurricane. We have never gone three years. If we do not see a hurricane make landfall this year for the third year in a row, it would be a first.