Tuesday 9:45 a.m.
A southwesterly flow of warm, moist air ahead of a cold front is contributing to a band of rain and thunderstorms that stretches from the Ohio Valley into parts of the Middle and North Atlantic states. We expect some showers and thunderstorms to cross the I95 corridor from D.C. to Boston later today and this evening.
The cold front should slip south then stall from Virginia or Maryland to Kentucky tomorrow. With the front likely to make only limited progress, some additional showers may occur tomorrow from D.C. to New York City and on west. Most of New England should turn sunny.
In general, computer models suggest a low pressure area forms along the front in the Middle Atlantic states on Friday then slowly moves up along the coast this weekend. If that happens, it will be a damp weekend in the I95 corridor of the Northeast.
In contrast, most of the Great Lakes region looks like it will bask in sunshine with afternoon temperatures in Detroit and Chicago close to 70 and nights cooling to the 40s and 50s. The video has more.
In the longer range, the re-curving of the latest western Pacific typhoon may signal an upper air trough (and cool weather) in the Northeast in a week to 10 days.
Late September is not generally known for widespread thunderstorms, but this map shows near 50,000 lightning strokes in the period from 8 EDT last night until just after 8:30 EDT this morning.
This map shows lightning strokes from 8 a.m. ET yesterday through 7:54 a.m. ET today. There was quite a bit of it in Utah, Colorado, New Mexico and Arizona. For the whole map, 156,172 lightning strokes were recorded.
Looking at the west-to-east upper air flow over New England well ahead of the storm, it seems like the hurricane should stay out at sea, However, as we look through the series of maps, we see the upper-air flow congealing into a strong eastern trough that helped the storm to come right up the coast instead of heading out to sea.
On this satellite picture, we can see the basically dry weather in the Eastern states. The cold front that will ease the midweek heat in the Northeast is shown by the band of thunderstorms in the Midwest. The thunderstorms may weaken and become more scattered as the front comes into the Northeast.
A storm in the tropical Atlantic is being observed for possible strengthening. This map shows the variety of models purporting to show where the center will go. Most solutions suggest it stays well offshore, but you will notice a few outliers suggesting more threat.
For example, the purple line in the east marks the boundary between air coming in from the ocean and a southwesterly current of warmer air. That boundary was the scene of showers and thunderstorms when it was in the middle of Pennsylvania yesterday, and was associated with rain that moved through the Hudson Valley early this morning.
Looking ahead to late next week, some of the computer models suggest a hurricane could affect areas between the Gulf of Mexico and the Atlantic east of the Bahamas. We are entering the prime part of the Atlantic hurricane season, but at this point there is only one model I am prepared to accept: