By Heather Buchman
AccuWeather.com
Weather conditions will be deteriorating across parts of the mid-Atlantic Thursday into Friday as an offshore storm system draws closer to the coast and eventually pushes onshore.
Heavy rain and localized flash flooding will be the biggest concerns, though beach erosion, rough surf and rip currents will also result.
The storm, which brought flooding rain to parts of North Carolina earlier this week, will continue spreading rain into parts of the mid-Atlantic tonight into Thursday.
The heaviest rain, however, is expected to arrive as the storm moves onshore late Thursday into Friday, targeting an area from the coastline of Delaware and New Jersey on west-northwestward through the higher elevations of eastern Pennsylvania.
Between 1 and 3 inches is likely within this zone, which includes Rehoboth Beach, Del., Atlantic City, Philadelphia, Scranton, Pa., and New York City. Locally higher amounts between 3 and 5 inches are possible within this zone, especially along the coast and at the higher elevations.
Rainfall on this order can cause localized flash flooding and travel disruptions. People should be ready for slow traffic and airport delays, especially late Thursday into Friday. Detours may result in areas where roads become flooded.
The other factor that will have an impact on the beaches will be persistent onshore winds through Friday. The interaction between the storm system and an area of high pressure to its north has been and will continue creating these onshore winds along the coast of the mid-Atlantic and southern New England.
It is the long duration, a two- to three-day period, of these onshore winds that will cause water to pile up on the coast and lead to coastal flooding. This threat will be greatest during times of high tide.
The strongest winds will average between 20 and 30 mph with gusts up to 45 mph, lasting for a 12- to 24-hour period Thursday into Friday. More information on the expected winds with this storm can be found in this AccuWeather.com headline.
Rough surf and rip currents will also be hazards to boaters and beach-goers.
The storm will eventually take a turn more to the north later Friday into Friday night, spreading rain through more of New York and New England, while rain lightens up or tapers off across the mid-Atlantic.
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While nasty storms end up targeting the northern Plains and Upper Midwest again the next couple of days, most of the hard-hit central Plains will catch a break from the flooding rainfall of the past few days.
A storm system developing over south-central Canada Thursday will drag a cold front into the Dakotas. Strong storms will develop along and ahead of this front over the eastern Dakotas Thursday evening and spread into western Minnesota overnight into Friday.
Damaging winds, large hail and flash flooding will be the main threats. Some cities potentially at risk for these storms include Fargo, N.D., Aberdeen and Sioux Falls, S.D., and St. Cloud, Minn.
While a few isolated drenching storms will be possible farther south across the central Plains through Friday, most of Kansas will catch a much-needed break from wet weather.
Storms late Monday into early Wednesday dumped heavy rain across the state with some locations picking up 6 to 8 inches or more. There were numerous reports of flash flooding along with road closures and water rescues.
While much of Kansas will stay dry through Friday, the cold front is expected to bring storms, some strong, back to the state Friday night into Saturday.
Farther north, the front is expected to stall over Minnesota and Iowa into Saturday before fizzling out. Thus, more storms will be possible across these states for the start of the weekend.
As for temperatures, highs will be well above normal across much of the northern Plains ahead of the front Thursday. Temperatures will surge well into the 80s and even 90s across some parts of the Dakotas and western Nebraska.
The front will erase this warmth, cutting highs back by 10 to 20 degrees and making it feel more like fall again.
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The AccuWeather.com Hurricane Center is monitoring the potential for development in the southwestern Gulf of Mexico late this week or early this weekend and any potential impacts on the southeastern U.S.
The Southwest Regional News story covers this potential more in detail. As a basic run-down, an area of low pressure could develop into a tropical system near the Texas coast Friday into Saturday.
There is some indication that this feature, whether it develops into a tropical system or not, will head north-northeastward over the weekend and impact the central Gulf Coast states.
At the very least, this system will usher tropical moisture into areas from Louisiana to Georgia and northern Florida, supporting heavy thunderstorms into early next week. Flash flooding will be a concern, especially for the lower Mississippi Valley this weekend.
In the meantime, the Southeast will remain stuck in a familiar pattern through the end of the week with fog starting off each day and spotty thunderstorms popping up across large portions of the region in the afternoon hours.
The extent of the thunderstorm activity this week is more typical of what you'd see in June rather than early September. September is typically a less active month for the interior Southeast.
Storms will continue to affect the lower Mississippi Valley, the southern Gulf Coast states and the southern Appalachians. Locally drenching storms will affect central and South Florida as well.
One phenomena that is more typical of the late summer is fog formation. Fog will continue developing during the overnight and early morning hours across much of the region through the rest of the week.
AccuWeather.com Expert Senior Meteorologist Alex Sosnowski contributed to the content of this story.
