Afternoon Update for April 22, 2010

Just going to throw up the WV, so I can show you guys a few things.

As of 12Z, the surface cold front was located back into NW PA and Upstate NY. Another interesting thing, clearly seen on the WV imagery, is the presence of a potent shortwave trough, clearly shown treking eastward through NY State. The trough will do two things: 1) help to steer the cold front eastward, and 2) to initiate convection.


Now, will we see showers and possible thunderstorms? That will be determined by how much surface based instability there is to work with. Less instability to work with, less thunderstorm activity to work with. Looking at dewpoints this morning, there not all that high, because the airmass in front of the cold front is not all that warm and steamy. Yes, there is drier air behind the front, but the airmass is not all that cold. So we're not going to see the classic clashes of airmasses. Dewpoints are only hovering in the 40's right now, not all that high. Like yesterday, there is a mid level cold pool aloft, as temperatures at 500mb range around -25C. So because of that, mid level lapse rates are fairly steep. So, we could see some surface cape develop out of and just along the cold front. This is from New Jersey into interior portions of CT. So with the developing surface cape and the approach of the shortwave trough, this may be enough to fire off some convection out ahead of the front. For the coastal areas, convection will fire west of the coast, because an afternoon seabreeze would have an stablizing effect on the atmosphere and convection should weaken once hitting the marine layer in place.


So a few thunderstorms could contain some hail, some gusty winds, and heavy rains. The front should clear the coast later on this evening, bringing with it, drier and slightly cooler air. Temperatures today will be in the 60's most places, with a few 70 degree readings to the SW.