Friday 9 a.m.
For a few days, the GFS model (a major U.S. model) has suggested that conditions may be favorable for snow showers downwind from the Great Lakes and into the mountains from West Virginia northeastward in about two weeks. The timing and extend of the event is changing with each new model run, but we expect that in a 12- to 16-day forecast.
In the short range, we see a low pressure area affecting the Middle and North Atlantic states. Most of the rain last night was organized into a band that extended from the ocean west-northwest through Maryland, Delaware and southern New Jersey into southern Pennsylvania. Harrisburg, Pa., had 6.35 inches of rain through 8 a.m. EDT. This means they had nearly double the average rainfall for the entire month of October in just one day! No wonder there has been major street flooding and widespread flooding of creeks and streams.
This radar composite shows the main rain area as it existed just after 8 a.m. EDT. The rain was moving toward the west-northwest, tending to dissipate as it moves through western Pennsylvania.
Here is today's forecast video for the weekend, plus a peak at what it may look like at the end of the week after next.
This satellite picture shows clouds over parts New York and Pennsylvania, as well as areas of low clouds, fog and snow cover from Michigan to Illinois. Most of the Northeast should have at least some sunshine through Thanksgiving Day.
As we go through the week, the flow aloft over the East will become southwesterly. This will promote a major warmup. This map shows the projected upper-air flow for Thanksgiving afternoon:
A major snowstorm will affect the area from Iowa to Michigan tonight and tomorrow. At first, snow can melt on streets, but as it continues and the temperature drops, the area impacted by slippery conditions will increase dramatically. This map shows expected accumulations:
This map shows two cold fronts in the northeast quarter of the nation; 9 a.m. ET temperature are plotted. The isobars are closest together over the central and western Great Lakes, and this is where the strongest winds were occurring.
This map shows how large an area is directly affected by precipitation on Tuesday morning. The low pressure center was in Kansas early today but will move all the way to Hudson Bay by Thursday while sending a cold front eastward on its south side.
A storm now moving through the Rockies will tap moisture from the Gulf of Mexico to threaten the central state with flooding rain. This map shows the GFS-predicted rainfall for the period from today through midday Friday.