By AccuWeather senior meteorologist
Published Aug. 27, 2020 11:52 AM
Following its historic and deadly path through the Gulf Coast, Laura weakened into a tropical rainstorm prior to crossing the Appalachians. But even in its weakened state, the storm may still be strong enough to bring damaging impacts to areas of the Northeast and mid-Atlantic.
The storm could continue to produce drenching rain and the risk of isolated tornadoes to some areas of the East Coast during the weekend.
The circulation center of Laura will continue to unwind as the system turns eastward and accelerates; however, enough energy may remain to continue to cause trouble from central and eastern North Carolina, eastern Virginia, central and southeastern Maryland, Delaware, southern New Jersey and perhaps southeastern Pennsylvania during Saturday and Saturday evening.
Interaction with the non-tropical storm system has the potential to bring locally severe storms to eastern New York state, northern New Jersey and part of New England. However, this severe weather threat maybe dependent on the amount of daytime heating from the sun.
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The Chesapeake and Delaware bays are significant moisture sources due to their very warm water this time of the year. These water bodies can also create subtle changes in air temperature, which sometimes fuel rotating thunderstorms, provided a system such as a weak tropical feature is in the vicinity.
AccuWeather meteorologists cannot rule out damaging wind gusts and isolated tornadoes and waterspouts in the mid-Atlantic region on Saturday as a result of the geography and the path of Laura.
People spending time outdoors on land or the water should keep an eye out for rapidly changing weather conditions on Saturday.
Fast forward motion of Laura should limit rainfall to a general 1-2 inches with locally higher amounts from the southern Appalachians to the mid-Atlantic coast spanning Friday night to Saturday evening. While this is not likely to cause widespread problems and can ease pockets of abnormally dry to drought conditions in the area, there can still be a few incidents of flash urban and small stream flooding.
Joining up with Laura will eventually be a non-tropical system--a cold front in this case. That front will help bring showers and thunderstorms to the Northeast in lieu of Laura's presence. Heating of the day may allow some of the storms to become locally severe over parts of the central and northern Appalachians to the New England coast.
Strong wind shear, or the change in speed and direction of the wind at different levels in the atmosphere, will also help to enhance thunderstorms across northern New York and into Vermont and New Hampshire.
The strongest storms will be capable of producing hail, damaging winds and isolated tornadoes.
While there was potential for Laura to regain tropical characteristics once the storm moved out over the warm waters of the Atlantic Ocean this weekend, this scenario is now unlikely to occur.
Laura has largely dissipated after interacting with land for the past several days. In addition, strong wind shear created by the approaching cold front and corresponding southward dip in the jet stream has helped to disrupt the storm.
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Beach and boating interests should monitor the progress of Laura this weekend. A period of gusty winds, rough surf and heavy seas can occur along the mid-Atlantic and New England coasts, especially if Laura gets its second wind.
Regardless of regeneration, it appears both systems will tend to merge over the Gulf of St. Lawrence region and Newfoundland and Labrador later this weekend. An area of drenching rain and gusty winds is likely. Some of the heavy rain can extend westward for a brief time across portions of Maine.
How much wind occurs in Newfoundland will depend on whether or not Laura regains tropical storm strength.
There is the potential for 2-4 inches (50-100 millimeters) of rain to be unleashed from coastal Maine to Newfoundland as the two systems get together later this weekend.
In the wake of the non-tropical system and Laura combination, cooler and less humid air will sweep across the Northeast during Saturday night and Sunday.
For parts of the Ohio Valley, mid-Atlantic, central Appalachians and the interior South, this may be the most refreshing air mass change since the first part of the summer. However, it will be brief as humidity is forecast to return early next week.
Keep checking back on AccuWeather.com and stay tuned to the AccuWeather Network on DirecTV, Frontier and Verizon Fios.
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