Wednesday, July 2, 2014

Arthur, Severe Storms, Floods And Your (Possibly Nice) Fourth Of July

Tropical Storm Arthur off the coast of Florida at
8 a.m. Wednesday.  
The Fourth of July holiday weather still looks like it will get off to a rocky start in parts of the East, but the weekend itself looks salvageable.  

In fact, the worst of the weather in most places looks like it will be in the run-up to the holiday: Today, tomorrow, and the first part of the Fourth of July.

(For my fellow Vermonters, this applies to you, too)

All eyes are on Tropical Storm Arthur, of course. The biggest problem still looks like it will be in eastern North Carolina.

The Outer Banks and other coastal areas of North Carolina are packed to the gills with tourists, and businesses there were anticipating a huge Fourth of July weekend.

Now, however, there's a hurricane watch up for eastern North Carolina and tropical storm watches up for areas just to the south and north.

Arthur, which had peak sustained winds of 60 mph as of Wednesday morning, is still expected to strengthen, move north and pass very close to the tip of Cape Hatteras early Friday morning. Those areas can expect hurricane force winds of up to 85 mph, torrential rains and high tides.

Some people will certainly be evacuated ahead of the Fourth of July weekend, so that ruins some vacation plans. Which is better than drowning in a storm surge if you stay behind, however, so there's that.

Arthur will then head northeast, and it's effects might brush Cape Cod and the islands Friday night and Saturday with strong winds and heavy rains, but Arthur's harshness will depend upon how close it comes to the coast.

Of course Arthur isn't the only problem the East Coast is facing. First of all, it's hot. Burlington, Vermont, for instance, had its first 90 degree summer day yesterday, reaching 92 degrees. That's just four degrees shy of a record high.

Heat advisories are up today for much of New Jersey and the area around Washington DC.

A cold front is still pressing into that zone of hot, humid weather. That situation is still expected to spark severe thunderstorms today.

Already there have been a few. A handful of warnings and damage reports came from  New York State yesterday. In fact, a roof of a house was blown off southeast of Syracuse.  Also, a quick moving batch of strong storms zipped through central Vermont just before dawn today.

The real action will start this afternoon. The sun's heat, combining with the humidity and the instability in the atmosphere caused by that approaching cold front, will trigger severe storms.

It looks like the zone of greatest risk is all of New England except the southeast (which will have its own problems with Arthur Friday night and Saturday).  I think most of Vermont and western New Hampshire are at the biggest risk for severe storms today.  
A small storm lets go of a streamer of rain
west of St. Albans, Vermont on Monday. Much
stronger or severe storms are
possible in that area today.  

Also in today's severe weather zone is all but far northwestern New York, and much of Pennsylvania, New Jersey, Maryland, Virginia and West Virginia.

Not everybody in this zone will get a severe storm, of course. As always in this situation, most areas will see some rain and thunder, but only a select few lucky or unlucky communities will get a severe storm.

The tornado threat is low, but there is a very slight chance of a brief twister in western New Hampshire, pretty much anywhere in Vermont, eastern New York and northeastern Pennsylvania.

Almost all the severe weather will come in the form of strong wind gusts blasting over 60 mph and torrential rains. A few spots might also get large, damaging hail.

There's a local flash flood risk as well. There is a HUGE amount of moisture in the air, and those thunderstorms can let loose with one to three inches of rain in just an hour or two.

Even after the severe thunderstorm risk diminishes tonight, the flash flood risk for almost the entire Northeast will continue through Thursday and Thursday night.

That pesky cold front will tend to stall out as it waits for that equally pesky Arthur to pass by. Deep tropical moisture, partly from Arthur, will feed into the cold front and trigger areas of torrential rain.

That'll happen Thursday in pretty much all of New England, down into New York, and the Mid-Atlantic states.  

Not everyone in this zone will get torrential rain, and it's hard to predict much in advance who will get it. But prepare for some torrential thunderstorms just in case. There will, again, be some local flash floods.

On the bright side in all this lousy weather, we do see signs of improvement in a few days. In the interior Northeast, away from the coast, conditions will slowly improve on the Fourth of July with increasing sunshine, lower temperatures, lower humidity and a nice northwest breeze.

Here in Vermont, I think most of the Fourth of July parades will go off without a hitch, as will the Friday evening fireworks. (Things look a bit iffy but not hopeless in the weather department for the fireworks in Burlington, Vermont Thursday evening)

Saturday in most places looks fine, except in southeastern New England near, (sigh!) Arthur. Sunday looks fantastic in most places, too.  It'll be sunny, and warm, and not that humid in most of the Northeast.

One word of caution: Even though the weather will turn nice all up and down the East Coast over the weekend, the ocean will still be churned up by (sigh!) Arthur. That means there's a risk of nasty rip currents, waves and such that could cause drownings at ocean beaches.

Be careful out there.


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