Thursday, 9:30 a.m.
In the video, we look at prospects for the coming weekend and early next week in the Northeast and Great Lakes. Also, we visit the latest version of the forecast for 2 p.m. on Oct. 10. You may recall that we looked at this date on the GFS model early this week and saw what appeared to be a heavy wet snowfall underway in central and northern Pennsylvania. If you don't recall seeing that map, let me say this: we looked at this date (Oct. 10) on the GFS model early this week and saw what appeared to be a heavy wet snowfall underway in central and northern Pennsylvania.
One feature that will affect the weekend weather will be a strengthening trough aloft that heads for the eastern Great Lakes. It will trigger showers, perhaps some thunderstorms and even waterspouts over the Great Lakes as it moves through. This prog map shows where it could be early Sunday morning:
That moisture may move away for the afternoon, but thunderstorms will erupt farther west where morning and midday sunshine adds fuel to growing cumulus clouds. This forecast map from the main U.S. model suggests little or no rain in the I-95 corridor from Maryland to Maine tomorrow afternoon.
The surface pressure pattern looks chaotic today, with a multitude of trough lines. A few of these can be caused by glitches in the data, but any of the real ones could be all that's required to organize a short band of showers or thunderstorms. However, these features tend to change character with time, or they disappear and new ones pop up.
Here's a cool fact: even when Death Valley, California, has a temperature of 110 or 120 degrees, you only have to go up a little more than 3.5 miles to find temperatures at or below freezing.
It appears the dry comfortable air mass now in the Northeast will be replaced by a humid flow from the South Atlantic states for the coming weekend. An upper-air forecast map sequence in the video shows how this could happen. The following map shows the predicted flow from Florida to New Jersey Friday night.
This map shows the pressure analysis for the Northeast and Great Lakes. The gusty flow on the west side of the low pressure area adds a real autumn feel to the air.
Since individual lines and clusters of thunderstorms have limited life spans and change character constantly, forecasting whether it will or won't rain at any one time this weekend is difficult at best. One solution is to have your tablet or phone available with the AccuWeather.com app so you can see where all the storms are at the times when it concerns you the most.