Well, that's strange.
It's a little unusual to see such a sprawling risk for severe weather as we approach the middle of August, but a robust system swinging into the eastern United States will trigger multiple lines of severe storms through the day on Monday.
The Storm Prediction Center issued a very large enhanced risk for severe weather—a level 3 out of 5 on the scale measuring the risk for severe storms—stretching from Birmingham to Philadelphia.
Plenty of hot, muggy air parked over the eastern states will provide the fuel needed for thunderstorms to roar through the day Monday, largely sparked by a cold front advancing into this summertime airmass.
Forecasters expect enough instability and wind shear for these storms to organize in a hurry and turn severe. Far and away the greatest threat with these storms will be damaging wind gusts. We're likely to see the storms develop into numerous squall lines, with each one likely capable of producing 60+ mph wind gusts as they push through.
Storms will likely form west of the Appalachians by the early afternoon Monday, steadily pushing east through the late afternoon and evening hours.
The SPC's forecast on Sunday showed a very large area at risk for damaging wind gusts on Monday, with the greatest threat concentrated on the I-85/95 corridor from Birmingham north through the Philly area. There's a decent chance that the strongest storms could approach the D.C. metro area through Monday afternoon and evening.
There's a chance that some of the discrete thunderstorms—the loners that form on their own, away from the interference of nearby storms—could develop some rotation, bringing with them a threat for large hail and possibly a tornado or two.
We could also see little 'kinks' develop along the leading edge of some of the squall lines, bringing the potential for a quick tornado or two embedded within the stronger lines of storms.
Things will calm down once the cold front pushes through, and most folks across Tennessee/North Carolina and northward should enjoy a touch of lower humidity on Tuesday and Wednesday.
 |
| A climatology map showing where damaging winds in severe thunderstorms are common on August 7 in any given year. (SPC) |
So...why is this strange, exactly?
August is usually the doldrums when it comes to weather east of the Mississippi River. Around this time of year, the jet stream is typically all the way north in Canada, allowing any low-pressure systems to swirl through the Plains before lifting north of the international border.
That relative lack of an active pattern leaves the eastern third of the country to the whims of tropical systems in the Atlantic or pop-up thunderstorms fueled by daytime heating—those random storms that bubble up where they may, raging for an hour before fizzling out with the loss of sunlight.
But the pattern over the U.S. and Canada in recent weeks has allowed these robust systems to track farther south than they normally would, essentially creating a setup where we have May-like storm systems tracking into the full-blown August heat.
0 comments: