Friday, July 31, 2020

Hurricane Isaias Now A Threat To U.S. East Coast

Now-Hurricane Isaias is yet another over performer, taking advantage of the jet fuel warmth of this
Hurricane Isaias is looking a little 
disorganized this morning due to 
strong upper level winds interfering
with it. 
year's tropical Atlantic Ocean waters to intensify.

This, despite a tussle with the mountains of the Dominican Republic, which should have at least kept Isaias somewhat in check. 

But as the mountains there tried to disrupt the system, a new center seemed to form just north of that island and away we went. 

At last check Isaias was packing winds of 80 mph and will probably keep strengthening as it hits the Bahamas today.  Not good, since the northern Bahamas were trashed by Category 5 Hurricane Dorian last year, so another blow from a hurricane is not needed.

The future track and intensity of Isaias is still a little questionable, as it is for all tropical systems. But the hurricane is a United States threat from Florida all the way to Maine and possibly beyond. As of this morning, Isaias was waging a battle with some strongish upper level winds, which were messing with its organization and ability to strengthen rapidly. 

The water ahead of Isaias is super warm, though, so that should help the storm at least maintain itself, if not get more powerful.

Once Isaias reached a point near the East Coast and starts moving northward, a couple dozen miles either way east or west in its track can make a big difference. Isaias is now expected to take a track parallel or even possibly over the Eastern Seaboard.  If it stays well offshore, that's a good thing. Then it won't be too bad.  Close or over the coastline, then you have a real problem. 

If it makes landfall anywhere between Florida and North Carolina south, it will be a HUGE mess for those regions between now and Tuesday or so.  Or, Isaias could stay just off the coast until it crashes into Long Island mid week or so, causing havoc there and in eastern New England.  Or it could stay off the coast and give just a glancing blow.

All of those potential scenarios are on the table right now. 

Intensity is a question too.  The waters along the entire East Coast are much warmer than average. Hurricanes tend to weaken as they approach the Northeast because of chillier water up there.  But this year's bathwater would tend to slow that weakening trend with Isaias. 

If Isaias makes a solid landfall in North Carolina or points south, the main threat in the Northeast would not be really be wind but torrential rains instead. 

 If it goes directly at Long Island or New England,  that neck of the woods could have a full-fledged hurricane, perhaps similar to Hurricane Bob in 1991 which actually made landfall in southeastern Massachusetts that year as a Category 2 hurricane with top winds of 100 mph with higher gusts. That storm caused $680 million in damage in New England.  

The best case scenario would have Isaias make a good right turn and stay off the coast altogether.

Even before Isaias gets near the Northeast, if it does, something called a Predecessor Rain Event or PRE's that can occur ahead of a hurricane or tropical storm along the East Coast. 

This is an area of very heavy rain that sets up well north or northwest of a tropical storm moving up from the south.  They are often located 500 miles or more north of the actual storm. They can cause tremendous flooding and definitely should be taken seriously. 

PRE's are hard to forecast. They're especially hard to figure out where they will set up.  On Sunday, some type of storm will head northeastward out of the Ohio Valley toward the eastern Great Lakes. It's possible the combination of this and Isaias could set up a PRE, although we don't know yet if that will happen, or if it does, exactly where.  

It just means there's potential for trouble even for locations away from the coastline.  

Florida is a real concern if Isaias hits there.  If any evacuations or damage occurs, it will be more complicated this time in Florida than it was with Dorian. 

Already, the state has decided to close coronavirus testing centers due to the threat from the hurricane.  That will affect the level of care people get, and assessments of how its spreading. The Florida state government has already done an abysmal job with this pandemic, and this will only make things worse. 

As I already noted, Isaias is a threat to a very big and very populated East Coast, so this could be a nightmare of evacuations, damage and fear mixed in with the coronavirus. They'd said we might be in for a bad hurricane season this year, which is never a good thing.  The timing this year with the pandemic could not have been worse.

Let's hope the computer models that keep it further off the coast are correct. But of course it's too early to know that yet. 

VERMONT EFFECTS

We have no good idea yet how, or even if, Isaias will affect Vermont. At this point, at least, it's looking more like a 1991 Hurricane Bob than a horrible 2011 Irene, but we still have to be alert, as that could change. 

Vermont escaped the worst of Hurricane Bob. All we got was a day of rather heavy rain and gusty, but not super damaging winds in southeastern Vermont and light rain in the northwest.  Of course we all know what Hurricane Irene did to us. 

Forecasters don't yet have a good handle on what kind of effects Isaias would have on Vermont.  Unlike the wet summer leading up to Irene in 2011,  most of Vermont is abnormally dry or even in a drought, so there's more capacity to soak up heavy rains than there was in 2011.

Of course, the heaviest rains fall to the northwest of a hurricane or tropical storm track, so it's possible we could have some flooding.  Especially if we are unlucky enough to fall under one of those PRE's I mentioned above. 

As you've seen and heard me say several times, just stay tuned on this one.  Before we even get to the middle of next week, we have Sunday's inclement weather to deal with. 

Early indications are the most rain Sunday will fall to our west.  Also, if a warm front moves far enough north on Sunday, there could be a severe storm or two. Before that, things will be benign, with just a low chance of a shower or garden variety thunderstorm this afternoon. 





 

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