February 26, 2003
Quite a difficult forecast for the next 48 hours in regards to potential wintry weather in Southeast PA. We have a wide spread of guidance solutions ranging from a dusting of snow (starting this afternoon), another model puts down 0 QPF today but starts us with a rain/sleet mix Thursday evening turning to moderate sleet/snow at night with accumulations, and we have another model giving us a virtual repeat of the President's Day Storm from last week! Needless to say, it's going to be very touch-and-go around these parts for the next 2 days.
The culprit(s) for the nasty weather with be an upper level disturbance tracking Eastward across the nation. At the surface, there will be weak low pressure development, but with strong high pressure in place over the Northeast once again, overunning or warm air advection snows willl be likely across the region starting later this afternoon (already reports of 1" in DCA and a solid coating on the ground in South Jersey). Highs today will be near 30 with accumulations up to an inch possible, especially the farther South one travels in our area.
The precipitation should taper off late tonight and early Thursday morning across the area, but this only sets the stage for what looks to be Part 2 moving in later in the day on Thursday. With high temps in the mid 30s on Thursday. With surface temps being above freezing, concern for travel problems are not an issue at this time, as whatever falls will not freeze to the surface but will keep roads wet. However, after dark is another story.
A mix of snow/sleet/rain will start later in the day on Thursday and will continue into Friday. As is usually the case, our area will be right on the fence between very heavy snowfall and a cold sleet and rain mix. At this time, most guidance brings the cold air back into the system turning any mixed precip to all snow by midnight Thursday. On the other hand, the rain/snow line has taken a notable Northward shift the past few runs of guidance, and this does concern me. If the redeveloping system should track about 25-50 miles farther North (and West) than currently progged, we are in for a cold, raw rain storm Thursday night. If the system holds it's current course, we get walloped with up to 10" or possibly a foot of snow! If the system track about 50 miles farther South (and East), we get a few snow flurries Thursday night into Friday.
In any event, precipitation will taper off in the morning on Friday and partial clearing will tru and take place with high temps in the mid to upper 30s. A nice weekend does look to be on tap with partly cloudy skies each day and high temperatures in the 40s both Saturday and Sunday.
Now in laymans terms, here is what I am thinking. As yesterday, I am once again going against most guidance and will go with a mixed precipitation event for the majority of the storm's duration turning to all snow before it ends on Friday. Accumulations will be up to a few inches, but could be significantly higher or lower if the storm track shifts just a matter of 50 miles in either direction. Still a confusing system with a short bit of time to look over more data and try to decipher exactly what Mother Nature is deciding to do. Will add another update late tonight or very early Thursday morning. Till then take care!
S.B.
