Cool Satellite Shot: A "Dry Slot" Moving Into the Region

Visible satellite image from late this morning shows a
very well defined "dry slot" a narrow band of clear air
on the east side of a storm over the Great Lakes. Dry slots
are very common in mature storm systems. 

 The visible satellite image of the northeastern United States and southeastern Canada was fun and interesting late this morning, at least for a weather geek. 

It shows what is known as a "dry slot" extending up through the eastern United States. You can see it in the satellite image on this post. Click on the image to make it bigger and easier to see. 

Dry slots are very common with mature storm systems.  A relatively narrow band of dry, sinking air gets entrained into the southern and eastern parts of a storm.

Sometimes, it stays cloudy in a dry slot, but precipitation largely shuts down. Other times, the sky gets clear in a relatively narrow band.  That's what's happening here.

A parent storm is over the Great Lakes, bringing in cold, cloudy air to that region, with rain and snow showers. The storm's cold front has pushed on into eastern New England. A classic dry slot has formed, and as of late morning, extended from the Carolinas, through central Virginia, Maryland, New Jersey, eastern Pennsylvania and central New York. 

On either side of this narrow dry slot, it's cloudy and cool. Under the dry slot, skies are spectacularly clear. It's still not particularly warm, but it is pleasant under it. 

The dry slot was edging closer to Vermont late this morning, so it gives us the prospect of sun breaking out this afternoon. Which will be a terrific alternative to the gloomy conditions we had this morning.  The dry slot's clear skies should linger tonight.

That means there's a good risk of frost in the Champlain Valley, where the growing season is technically still going. The National Weather Service has issued a frost advisory for this area tonight. 

 Temperatures in much of Vermont will be near or below freezing tonight.  The growing season is considered over in these areas, so there's no frost or freeze alerts outside the Champlain Valley. 

This is the second classic dry slot we experienced in a week. On Friday, after an early morning of heavy rain, skies abruptly became clear and pleasantly mild in much of Vermont last Friday afternoon.