Dorian Doomwatch, Wednesday Morning 28 August 2019

Dorian continues to defy the odds to an extent, and is not only holding together but tracking to the right of the forecast tracks.  In part because of the small size, Dorian is not “entraining” dry air as a normal-sized storm would, so is holding together and even intensifying more than perhaps it should.  As always the two questions are where and how bad.

Here’s this morning’s “primary” track models.  GFS main has trended north towards the SEUS coast over the last 12 hours, indicating a ridge of high pressure will have a “weakness” the will allow the storm to turn.  The ever sainted ECMWF and the Navy’s model keep it strong, and Dorian headed to Central Florida …

There are lots of local (Savannah GA area) amateurs, semi-pros, and attention … um, seekers … talking a lot about GFS (probably because it’s scary for people on the Georgia coast and gets them more attention.  Let’s take a closer look at that.  Here’s the GFS family of tracks available as of this morning …

The blue line is the primary model that is often used to generate scary graphics.At the moment it shows the storm brushing Hatteras.  Last night it showed Dorian right over Savannah.  6 hours before that it was over central Florida.  Get the point?  It is too unstable right now to get excited about.  Note the brown line, and the cloud of gray lines.  That’s the “consensus” of the GFS ensemble model, based on multiple initial conditions.  and variations.  Again, very wide spread.  Also note that NONE of these got the last few hours right – Dorian is well to the right of almost all of these already.

That’s the background.  What should you do?   Simple: ignore all the noise and the amateurs and even “pros” throwing out this or that scenario based on one model track that happens to be hitting your house.  For planning purposes there is only one place you need to go: the National Hurricane Center’s “Key Messages” page. And be careful about using that “cone of uncertainty” – NHC has a video on it talking about what it does and doesn’t mean.

As for the estimated impacts, here’s the forecasted impacts in plain English, from my Haetta/TC based model using the NHC forecast track as of 6am …

Bottom lines: In Puerto Rico you should have already planned for a Cat 1 Hurricane.  Sadly, on this track and intensity, you’re going to lose power again, and the system is still pretty fragile so it will be out for a while.  The biggest physical damage risk to PR is probably flash flooding; the worst of the winds will likely be over the ignored and  neglected US Virgin Islands.  Estimates are if the intensity follows the NHC trend, damages will be on the order of $400 to $500 Million, but as noted yesterday, the humanitarian impacts are likely to be disproportionate given the still fragile infrastructure.

For Florida, the next 24 hours or so will start to tell the tale, and if folks should begin to freak out or not.  (You, of course, have a plan and don’t have to panic until maybe Friday when the track will be much clearer).

For Georgia, South Carolina, and North Carolina, “Calm down, eat some fruit or something.”  As discussed above, if the ridge builds, Florida gets whacked.  If it decays a little, you might be in play.  If it decays a lot, it will stay offshore (think 1999’s Floyd).  We just don’t know which scenario will happen, and you still have time (assuming you have that plan) to plan your end-of-summer barbecue before you plan to flee.

8 thoughts on “Dorian Doomwatch, Wednesday Morning 28 August 2019

  1. I’m in Savannah and work for SAGIS. My coworkers and I greatly appreciate your blog. Thanks for always keeping it scientific instead of sensationalist. I also cracked up with the “Signs” reference. “Calm down, eat some fruit or something.” Thanks again!

    • You’re welcome! Sort of bugs me I have to do this, would really rather stick to my research behind the scenes.

      Glad you appreciate the movie reference. Some don’t appreciate the humor. Yes, this is serious stuff, but the over-reactions by some does deserve to be poked fun at …
      Calm Down ...

  2. Howdy. I noticed this site does not update as frequently as your FB page. I’ve relied on this data for years…hoping to get it in any way possible. Thanks for what you do!

  3. if the storm stays close to its current trajectory, and makes landfall is in central f
    Florida, the new moon hi tides Sunday, Monday & Tuesday are going to keep things interesting for coastal GA. Will you be modeling storm surge for those days?

  4. SCAD is telling all the RAs and other student athletes, etc to self evacuate by Saturday? Any idea how soon we’ll know if that’s really necessary? Hate to book flights to/from SAV/PITTSBURGH.

    • Wow, that’s a serious overreaction! At this point there seems to be no reason to do that. On the current path there should be few if any impacts in this area. We were already going to get some shallow coastal flooding (like US 80 closing around high tide) because of the new moon and some onshore winds, but that happens a couple times a year so it’s not unusual.

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