Florence Update for Thursday, 13 September 2018

Florence continues to “barrel” (funny how some words get stuck in the media) towards the southern North Carolina shoreline.  The short version is that for the immediate landfall area, not too much has changed.  Watches and warnings are the same, expected “worst case” impacts haven’t changed, etc.  There is some good news in the sense that the storm may not be as intense as forecast when it makes landfall, it’s down to Saffir Simpson category 2 levels.  That DOES NOT mean those in the warning areas should fail to prepare for a Cat 3 – there could be a bump in intensity before landfall, but signs are for a weaker storm than expected.  Still, will be bad enough, so if you haven’t gotten out, do it this morning before conditions deteriorate rapidly later today.  Winds along the coast are light so far (looks like 10-15 knots peak right now), but that is going to change rapidly.  Here’s a composite radar view from the two closest sites (Wilmington, range indicated in white, and Morehead City, range indicated in green).  Classic eye and banding structures becoming visible …

The various forecast track models and other simulations are in pretty good agreement that the storm will make landfall, then stall out for at least two days near the SC/NC border, over the Grand Strand. Here is the impact estimate based on the official NHC forecast as of 5am this morning:

This is the tricky part of the forecast – if it’s on the shore, or near the short, it can maintain intensity, and pump more rain inland.  If it’s even 50 miles further inland, the intensity and rain rates will drop off pretty quickly.  On the current track, the worst wind damage will stay in North Carolina.  Direct impacts should be around $10 Billion.  The big question is rain and flooding.  The current estimates are for about $5 Billion in additional impacts from rain related flooding.  But a longer pause could double that number; likewise, if the storm is even 50, much less 100 miles inland, that could easily drop to a Billion or so.  It’s a great unknown …

For folks in Savannah GA and the Beaufort/Hilton Head area, things look pretty good on this track.  We’re on the weak, dry side of the storm.  Winds will be offshore, so storm surge flooding will be nothing to worry about.  Right on the coast, waves and wave setup might cause some issues, and rip currents will remain dangerous.  Depending on wobbles, we may get rain, or just as easily get a clear if breezy day in the subsidence zone.  But dangerous conditions (other than on the beach) just don’t seem to be in the cards right now.

3 thoughts on “Florence Update for Thursday, 13 September 2018

  1. Hi, Chuck … long time / no see … hope all is going well with you and your wife … Crystal and I think about “Youz Guys” all the time … and we (and MANY others!) really like your web site AND the accurate, updated analysis presented in a most professional format … as they say, “Keep Up the Good Work!” … you’ve got a large following! If I am not mistaken, based on the latest projections, Savannah is basically “Dodging the Bullet” [again!] with Florence … of course, I understand that we still need to monitor but at the 50,000 foot level (like our Gulfstream NOAA plane!), we should be OK … my question/observation is then, why do sites such as WINDY.COM show Florence slamming into Savannah on Sunday? https://www.windy.com/?2018-09-16-15,32.181,-81.216,5
    Don’t these people care? I know … as you’ve noted on your site, they obviously are not scientists. If you wish, you can eMail me back at: jfarmaki@bellsouth.net
    Thank you again for being here and keeping us safe AND accurately updated! 🙂

    • I think it’s two factors. The first is using raw models, rather than forecasts. Raw model outputs need interpretation. Sites like windy, and most TV stations, decide to show a model based on its ability to product pretty graphics, not based on how good it might be in any given situation. They don’t really care if what they are showing is scaring the wrong people, they care it looks good …

  2. I hear you and totally agree … like the other evening The Weather Channel folks got “Bent Outta Shape” because Florence went from a CAT 4 to a 2 … they were scrambling to restore the “Fear Factor” to panic mode, again! Thanks for replying, Chuck!

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