Joe Lundberg

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Arthur Forms, to Sideswipe Eastern Seaboard

July 1, 2014; 11:27 AM ET

Tuesday, 11:55 a.m.

The first named storm of the Atlantic Hurricane Season has formed, with The Tropical Prediction Center giving the name Arthur to the low pressure area east of the Florida Peninsula. Up to this point, most of the thunderstorms associated with the low have remained south of the center of circulation, thanks to a persistent northerly wind aloft over the storm. That wind shear is beginning to relax, now, and as a result some of the thunderstorms appear to be trying to wrap around the north side of the storm. In time, assuming the winds aloft continue to relax, the thunderstorms should fill in around the northern half of the storm, which should serve to allow the storm to strengthen steadily.

Water temperatures off the Southeast coast are generally between 81 and 85 degrees right now, so that is not an obstacle to the storm's growth. So, with the upper-level wind shear relaxing, there's every reason to believe Arthur will intensify and could easily become the season's first hurricane before it approaches eastern North Carolina late Thursday night and early Friday.

Once the storm gets clear of the Florida-Georgia state line, it will begin to be guided by the upper-level trough diving into the Great Lakes and Ohio Valley. That will mean a steady increase in forward speed, and a gradual turn to the northeast Wednesday night and Thursday into Thursday night. By Friday, Arthur, either a strong tropical storm or a Category 1 hurricane, will buzz past the Outer Banks and should speed well southeast of Cape Cod Friday night.

By and large, the impacts of Arthur will be somewhat tangential. I do not in any way mean to diminish those impacts! However, if the storm fails to make landfall, then the winds that could do the worst damage will largely miss the coast. Still, power outages are likely over portions of eastern North Carolina, and perhaps southeastern Virginia and along the upper South Carolina coast. Heavy rain will also graze these same areas, while coastal flooding may be more of a concern in the coastal Carolinas. The surf will decidedly be up all up and down the Eastern Seaboard, starting tomorrow off the Southeast coast, but spreading north to include the mid-Atlantic and southern New England coastline Thursday and Friday. Please check out the stories on Arthur and its potential impacts at AccuWeather.com.

Meanwhile, behind the storm and the cold front that will usher it away from the East Coast Friday, a fall-like air mass will spread from the Plains eastward. And when I say fall-like, I mean it! Temperatures in parts of the Dakotas will be struggling to get much past 60 this afternoon with clouds, gusty winds and some rain showers. Temperatures could be as much as 15 degrees below average for the first day of July! And nighttime lows once high pressure builds in could challenge records in some areas for the next couple of night. Look at the projected anomalies for tomorrow:

The cool, dry air will sweep across the Mississippi Valley tomorrow. By Thursday morning, the surface high will build into the mid-Mississippi Valley:

This refreshing air mass will get to the Appalachians Thursday night and Friday, then, in modified form, jump over the Appalachians into the East later Friday, setting the table for a fantastic weekend, weather wise, with low humidity and plenty of sunshine Saturday. Even much of the holiday itself will be dry in the mid-Atlantic with a return of sunshine and lowering humidity.

The views expressed are those of the author and not necessarily those of AccuWeather, Inc. or AccuWeather.com

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About This Blog

Joe Lundberg
Joe Lundberg, a veteran AccuWeather.com forecaster and meteorologist, covers both short and long-term U.S. weather on this blog.