Florence Notes for Friday Morning, 7 Sept 2018

First the big picture (literally), the 6am IR satellite shot with storms labeled …

The three “invest” (investigation areas) will likely develop into storms over the weekend or early next week.  Of the two actual tropical cyclones, Olivia, currently a Category 3 storm, is forecast to weaken and may threaten Hawai’i as a tropical storm by early next week.  Worth watching but still a long way out.  The big focus today, competing with the shenanigans in the US political realm, is of course Tropical Storm Florence.

Florence is currently in a region of unfavorable upper level winds – you will hear weather forecasters talk about shear.  That means the winds at different levels of the atmosphere are moving in different directions and trying to tear the storm apart.  In this case it’s working – Florence is now below hurricane strength.  However, these winds are forecast to subside by tomorrow, and by Sunday Florence is expected to recover somewhat, perhaps becoming a Category 3 storm by Tuesday if it follows the forecast track … which is of course the big question. In simple terms, the future of Florence depends on high pressure to the north of the storm.  The exact location and configuration of this ridge of air will govern how far west, how much shear, and when the storm will turn northward.  The various global models that predict this sort of thing differ, thus the tracks differ a lot.  The bottom line is, as NHC emphasizes in their excellent “Key Messages” graphics, aside from increasing waves (swell, which has my surfer friends excited, but beware rip currents!) along the east coast , we just don’t know what the potential impact on the US East Coast will be. So if you live in a hurricane prone area from South Carolina northwards, especially NC and up, and have a plan, it’s not time to panic or be afraid.  Unless you are watching the news out of Washington.  Feel free to panic over that!

Here is this morning’s guidance, with a few models used by NHC highlighted …

 

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