Tuesday, July 8, 2014

Round 2 Of Severe Weather in Northeast, Ohio Valley Today

After a wild ride in some areas on Monday and a quieter than expected day up in northern New York and Vermont, expect more severe storms this afternoon and evening across the region.
A rotating supercell thunderstorm with
a possible funnel cloud passes just
north of downtown Boston Monday in
this Weatherbug view from Fenway Park. 

Those areas that missed out on the big storms Monday might end up with some today.

In yesterday morning's post, I said that an early Monday morning area of rain in western New York would either kill potential severe storms in some areas by limiting sunshine, or encourage strong storms in some areas by forming gusts of cool air that would act like mini-cold fronts to set off rough weather.

It turns out both things happened.

In the summertime, a key ingredient to severe storms is morning and early afternoon sunshine. The sun heats the atmosphere near the ground, increasing the temperature contrast between the surface and tens of thousands of feet up, where it's much colder.

That contrast helps form the billowing clouds that form thunderstorms. On Monday in northern New York and most of Vermont, the dying batch of showers, and their clouds, pretty much kept the sun out of the picture, limiting the atmospheric temperature contrast and, for the most part, prevented thunderstorms.

More to the south, that batch of morning showers had a push of coolish air coming out it's south end.

That acted a bit like a snowplow creating enough lift to set off a line of thunderstorms that went through the Capital District of New York and then moved toward the east and southeast into far southern Vermont and New Hampshire.

The line of storms kind of stalled along the Massachusetts border, and, as sometimes happens along or near these boundaries, a few supercell thunderstorms formed. The most notable one went across northeastern Massachusetts, through many of Boston suburbs and then just north of the city and out to sea.

That storm was rotating and had a distinct hook echo, indicating a tornado. Funnel clouds were spotted and photographed, but so far I have no confirmation a tornado touched down.

Today, another weather front looks like it will punch into the warm, humid air covering the Ohio Valley and Northeast, so another round of severe thunderstorms seems likely.  Up in northern New York and the northern halves of Vermont and New Hampshire, it looks like some storms there could get strong, unlike the false alarm of Monday.

There's a fair amount of sun out there, it's quite humid, so that's the fuel needed to get strong to severe storms going.

However, though there is the threat of severe storms in northern New England the upper tip of New York, it looks like the biggest threat for severe weather goes from southwestern Vermont, across much of New York State and Pennsylvania and into the Ohio Valley (Just like yesterday!)

Especially in New York, Pennsylvania and Ohio, there's the risk of some supercells, which maybe could drop a tornado or two. In any event, any place in a stripe from New England to Arkansas is at risk for damaging winds, hail, dangerous lightning, torrential rains and maybe some flash flooding.

Things will calm down somewhat in the Northeast and Ohio Valley by Wednesday.


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