Thursday 10 a.m.
The upper-air feature that has been pumping warm, moist air northward through the Eastern states is getting kicked northeastward by a wider trough that is taking shape farther west. The latter feature is sponsoring the southward push of colder air. Near the core of the cold air mass, temperatures dropped as low as the teens in parts of Montana. A few places had their coldest morning since last winter. In eastern North Dakota, Fargo was hit by gale-force, icy wind gusts carrying the first snow of the season.
The main thrust of the cold air will be across the upper Great Lakes and Ontario, but the leading edge of the change to cooler weather has already reached northern Texas. At Amarillo, it was 64 degrees at midnight with the wind out of south. At 8 a.m. CDT, it was 49 with a north wind gusting past 40 mph! The change to chilly will not be as dramatic when it reaches the East Coast, but it will certainly be noticed. Temperatures will be well up in the 70s in Boston tomorrow... and near 80 degrees in Philadelphia and Washington, D.C. On Sunday, temperatures in those cities will be in the 40s and 50s.
This morning's NMM-WRF run shows the band of rain associated with the leading edge of the change to colder weather crossing the Appalachians by midday Saturday. The rain shown on the map is the predicted amount from 8 a.m. until 2 p.m. EDT.
In the six-hour period after this (2 p.m. until 8 p.m. EDT), the rain band almost totally vanishes. I interpret the maps as suggesting I may not actually need the rain jacket that I will carry along anyway to the Penn State - Northwestern game on Saturday. I always carry the jacket in my golf bag so that if it does happen to rain, it looks like I predicted it all along!
This map shows the pressure pattern as it was early this morning. The low pressure center in western North Carolina will move out to sea tonight and the snow now falling farther to its north will collapse southward.
The part of the front over the Eastern states will move south this afternoon and tonight, then a low pressure area will move along it. The result should be snow from the Ohio Valley into the Middle Atlantic states.
The thin blue line is temperature. Notice how it is left of the black line near the bottom, meaning the ground level temperature is below freezing. Several thousand feet overhead, however, it is warmer than 32 degrees, so any snow falling through that layer melts.
Today is the National Education Association's Read Aloud Day. If you have young children or grandchildren, I hope you get the chance to read to them today, and on many other days. On today's video, I tried reading to you.
The storm moving from the Ohio Valley to the Middle Atlantic coast will cause snow and ice, Clearing should follow tomorrow, but another storm should bring snow and ice followed by rain from Maryland to Massachusetts.
Clearing should follow tomorrow, but another storm will cause snow and ice followed by rain from Maryland to Massachusetts late Tuesday into early Wednesday.