11:45 AM | ***Strong-to-severe thunderstorm threat repeats later today into early tonight across the Mid-Atlantic region…clears the way for a stretch of nice weather from tomorrow through Monday***
Paul Dorian
Strong-to-severe thunderstorms are likely later today into early tonight across the Mid-Atlantic region. Map courtesy NOAA, tropicaltidbits.com
Overview
A stretch of nice weather begins on Friday in the Mid-Atlantic region and continues through Monday, but there is a threat of severe weather before we get there. A strong cold front is crossing the Great Lakes region today and headed towards the Mid-Atlantic and its approach will enhance the chance for showers and thunderstorms in the 2-9 PM time period. Any storm that forms later today or early tonight can become severe with potentially damaging wind gusts and heavy rainfall…perhaps even a few isolated tornadoes. The good news is that all of this activity clears out by early tomorrow setting the stage for a stretch of nice weather from tomorrow through the Labor Day holiday.
One stability parameter known as the Convective Available Potential Energy (CAPE) is highest south of the PA/MD border and this suggests the greatest chance for severe weather later today is from the DC metro region-to-Delmarva Peninsula-to-southern New Jersey. Map courtesy NOAA
Short-term severe weather threat
Following the passage of a warm frontal system yesterday, temperatures climbed into the 80’s in the DC-to-Philly-to-NYC corridor and overall humidity levels rose noticeably. It’ll stay very warm and humid today throughout the Mid-Atlantic ahead of a strong cold front that is dropping southeast across the Great Lakes region. The surface cold front will not actually arrive in this area until late tonight; however, a pre-frontal trough will set up in the lee of the Appalachian Mountains and it will become the focus area for PM showers and thunderstorms. Any storm that forms later today will have the potential of producing damaging wind gusts and heavy rainfall and a few isolated tornadoes are even possible. All of this activity will clear the coast early tomorrow and set the stage for an extended stretch of nice weather in the Mid-Atlantic/NE US.
Thus unusual cold snap coming the the middle 2/3rds of the nation next week could even result in some early season snowfall in higher elevation locations. Map courtesy ECMWF, pivotal weather
Next week’s wild temperature pattern
The big story next week will be a widespread chill down in the middle 2/3rds of the nation as a cold air mass for this time of year drops southeastward from western Canada. In some places, the chill down may be quite dramatic. For example, there could be highs in the 90’s on Monday in Denver, Colorado and then a plunge in temperatures following the passage of a strong cold front resulting in highs on Tuesday in the 30’s. This chilly air mass will be aided by a strong upper-level low and it may even result in some early season snow in the higher elevations from western Montana to the Colorado Rockies.
Much colder-than-normal air will push into the middle of the nation next week at the same time both coasts become warmer-than-normal. Map courtesy NOAA, weathermodels.com
At the same time, warmer-than-normal conditions will dominate both coasts. In the west, temperatures are likely to climb to well above-normal levels leading to the development of more wildfires. In the east, as high pressure pushes off the New England coastline, a broad southwesterly flow of air will develop early in the week and this will lead to warmer and more humid weather in the Tuesday/Wednesday time frame which will follow the very nice weather of Friday, Saturday, Sunday and Monday.
Meteorologist Paul Dorian
Perspecta, Inc.
perspectaweather.com
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