Sunday 7:30 PM
When I last wrote to you Friday, I thought the main snow area would affect the area from Pennsylvania to Southern New England. Wrong answer! I also said since the storm was still more than two days away, it was important to check for updates. I'm sure you did that, and saw the axis of heaviest predicted snow kept creeping southward. It now appears the substantial snow will fall from extreme southern Pennsylvania and Southern New Jersey well down through Virginia.
The northward extent of the snow will be determined the progress of snow that was showing up on this picture from radar serving southwest Ohio. The is what it looked like just after 7PM ET.
The strongest part of the storm is represented by thunderstorms, as depicted on this lightning map for the period from 6 - 7 PM ET.
To the northwest of the storm system, a very cold air mass is spreading south and east. This new airmass will move south to hold DC temperatures in the 20s tomorrow, and send the mercury to the single digits as far south as the middle of Pennsylvania.
I'll write to you again in the morning.
This map shows the pressure pattern at 9 a.m. ET. As the high moves closer and the storm moves farther away tomorrow and Wednesday, there should be an increase in sunshine with milder afternoons.
This map is the GFS forecast for when weekend rain makes its most northward advance early Sunday. The model then shows drying from north to south during the day Sunday. The ensemble mean has the northern edge in the same area. Looking ahead, it appears that warmer air is coming when May starts.
This map shows the GFS model forecast for Saturday evening. In the last day or two, the models have trended northward with the precipitation. If it trends even farther north, the issue of possible snow would need to be addressed. Check back later for updates, please.
The GFS (U.S. Model) predicts a major storm for the Middle Atlantic in the middle or late part of next week. This map is the GFS forecast for next Thursday (April 30) at 8 a.m. ET. Just to put you in a better mood, the second map (for May 4) shows what would be a sunny and pleasantly warm spring day.
This map shows the pressure pattern earlier this morning. You can see the extensiveness of the area of west to east winds. As a storm north of the Upper Great Lakes moves eastward, the flow will become more northwesterly.
This year, the "slight" category has been divided in two: slight and enhanced. When seen together on an SPC map, the progression makes sense. When the term "enhanced" is used alone, it can be a challenge, at least until we get used to it.