30 August 2019

Dorian nearing Category 3 intensity and still has Florida in its sight

Hurricane Dorian is strengthening, and should become the season's first major hurricane later today as it tracks north of the Bahamas. As of 8am EDT, peak sustained winds are up to 110 mph and it is centered 520 miles east of Andros Island (Bahamas) and 660 miles east-southeast of West Palm Beach (Florida).

In terms of impacts, clearly the wind will be a catastrophic impact wherever a Category 3+ eyewall lands, but dangerous tropical storm force winds cover hundreds of miles and even that is unsafe to be outside in due to trees breaking and downed power lines.  As of Friday morning, the tropical storm force winds extend an average of 75 miles from the center, and hurricane wind fields tend to expand with time.

Additionally, storm surge will be a problem over a span of hundreds of miles, but especially near the northern eyewall with the onshore winds. Storm surge guidance along with watches and warnings will start coming in this weekend. There are also exceptionally high tides this weekend due to a new moon, so flooding will be exacerbated.  And speaking of flooding, a big swath of heavy rain is expected in association with Dorian -- adding to an already drenched month across a good chunk of Florida.

Uncertainty remains in where and when landfall will be. Model guidance has trended to slow the storm down as it approaches Florida, and as such, may not even reach the coast until Tuesday.  A slower storm just allows for more time over the warm ocean and more coastal impacts over numerous high tide cycles. The ensemble guidance has come into somewhat better agreement; although quite a bit of spread exists, the two major ensembles are presently clustered between Fort Lauderdale and Vero Beach.

Beyond the immediate threats in the Bahamas and Florida, Dorian does not just suddenly disappear unfortunately... there is a decent chance that it will recurve and track up the U.S. east coast next week/weekend, so anyone up there should also be paying very close attention and think about preparedness.

Assuming Dorian hits Florida, it will be the 4th hurricane landfall in that state in as many years (Hermine '16, Irma '17, Michael '18, Dorian '19), and if it hits at Category 3 status or higher, it will be the third consecutive year with a major hurricane landfall in the state (Irma, Michael, Dorian).  While that is a fairly active period, it doesn't break any records -- there have been more active periods in Florida's extensive hurricane history, such as 1944-1950 with 11 hurricanes and 2004-2005 with 7 hurricanes.

Finally, we can't neglect to keep our eyes on the rest of the basin as the peak of hurricane season approaches.  There is a strong tropical wave just leaving the African coast today and one that is about five days behind it.  Models generally develop both of them, and NHC is giving the western one a 30% chance of development within the next five days. The next two names on this year's list are Fernand and Gabrielle.


  1. It is a weird coincidence that so far it seems to be going straight to Maralago in Palm Beach. More than one will want to interpret it as a "Divine Punishment", as irrational as that may be. We will see.

    1. Would love to see some punishment for that address.

  2. You just said what a million people are thinking.