Talking the Tropics With Mike: Hurricane Michael strengthening on move north into the Gulf

Oct. 8, 2018 — The "Buresh Bottom Line": Always be prepared!.....First Alert Hurricane Survival Guide... City of Jacksonville Preparedness Guide... Georgia Hurricane Guide.  

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Hurricane "Michael" (not Buresh!) continues to organize & strengthen.  Forecast to hit the Fl. Panhandle as a "major" Cat. 3 hurricane Wed. afternoon.  This could be the most major hurricane to squarely hit the Panhandle since Ivan in 2004 which destroyed the I-10 bridge to Pensacola.

Given current forecast path - SUBJECT TO SOME CHANGES - between Mobile, Al. & the Big Bend of Fl. centered on the Central Panhandle, local impacts for Jacksonville, NE Fl. & SE Ga. are as follows:

* heavy rain in multiple bands through Thu. with the potential for 1-3" of rain, more in some spots.  Far more rain just offshore to the east & over NW Fl. & Panhandle into Ga. closer to what should be the center of Michael.  Looks like a relative lull in the rain Wed. due to dry slot pivoting north around the eastern side of Michael's circulation.

* breezy winds - combination of  "Michael" to the west & moderately strong high pressure to the north will result in brisk winds out of the SE increasing each day through Thu. averaging 15-25 mph with gusts 30+ mph.  Strongest winds will be at the beaches & from near Lake City to Waycross closer to Michael's center.

* isolated waterspouts &/or tornadoes, especially Tue. through Thu.

* high rip current risk at area beaches

* minor to possibly moderate flooding - especially at times of high tide - along the coast, intracoastal & St. Johns River & its tributaries due to a combination of strong/persistent onshore flow, occasional heavy rain & an astronomical boost due to the new moon phase. No significant storm surge is expected for NE Fl. & Jacksonville & SE Ga.

*** Far more significant impacts for the Fl. Big Bend, Panhandle, coastal Alabama & parts of Ga. & the Carolina's. Hurricane WARNING/Storm Surge WARNING Fl. Panhandle & Big Bend... Hurricane WATCH coastal Alabama & Tropical Storm WATCH as far south as Tampa Bay ***

REMEMBER: the "cone of uncertainty" is simply & only forecast error & has nothing to do with potential damage or damage swath.  Do not get too caught up in exactly where the center might be going.  Keep in mind that a more narrow cone simply means a higher confidence forecast.

History - going back to about the mid 1990s - shows we should be wary of Oct. hurricanes given certain conditions which are in place right now - see "Buresh Blog" - Matthew (Fl.) 2 years ago (Sun., 10/07!)... Joaquin (Bahamas & El Faro) in 2015... Sandy (NY, NJ) in 2012.... Wilma (Yucatan &Fl.) in 2005... Mitch (Central America & Fl.) in 1998... Opal (Fl.) in 1995.

Michael has steadily become more organized/symmetrical/larger while moving through the Yucatan Channel despite a good deal of mid & upper level shear.  The eye has become centered underneath the stronger, more persistent convection that was being sheared to the east. Overall outflow is becoming well established.

Global forecast models have come into good agreement on Michael's intensity - a hurricane - & have come into much better agreement on track - Fl. Panhandle BUT with timing differences.  I would expect models to become more consistent within the next day or so.  The GFS remains the fastest & farthest west - coming ashore Wed. afternoon/evening over the Central/Western Fl. Panhandle, give or take.  The European model is a little more east but a good 12-18 hours slower - landfall Wed. night/early Thu. & has trended even a little west now of the GFS.  The UKMET can sometimes be a good compromise & has shifted "nicely" to the west to join most of the rest of the modeling bringing Michael ashore Wed. night - now near the GFS & European solutions.  So it looks like the stubborn upper level high pressure that's been a mainstay the last 6 weeks or so near Jacksonville will essentially protect Jacksonville/NE Fl. & SE Ga. from a potentially major hurricane .... BUT stay up to date!!..... AND there will still be potentially significant fringe effects for the local area.

In any case... Michael looks to be a fairly swift moving tropical cyclone which means dangerous impacts will extend well inland.  Everyone from Florida to New Orleans should "hurricane prepare"..... & depending on where landfall is.... flooding, high winds & tornadoes could occur far inland over parts of Alabama, Ga., Fl. & the Carolina's (potentially bad news for Florence - wary Carolina residents).

Radar imagery below courtesy South Fl. Water Management District (magenta line indicates NHC Michael forecast track):

Caribbean:

Gulf of Mexico:

Spaghetti plots for Michael:

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Ensemble spaghetti model plots give us a good idea of the uncertainty & the array of possible outcomes in the coming days:

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"Bath water" over parts of the Gulf:

As for movement..... the long lasting Bermuda high summer-style system over or near the Southeast U.S. - that has brought an extend summertime weather pattern of heat & dry weather to Jacksonville - will be a major player regarding the ultimate track of Michael.  At the same time, a deep upper level trough will dig into the Western U.S.  Given additional upstream "energy" that has yet to become a part of this trough + the stubbornness of the eastern ridge the last 6-7 weeks, I have a tendency to favor a more western track.  Forecast models have generally come around to the solution bringing Michael to the Panhandle then turning NE as the upper level trough becomes more dominant & the ridge breaks down some.

As for timing... Wed./Thu. is when Michael will make landfall with the GFS earliest & farthest west... the UKMET Wed. night.... & the European early to midday Thu. but a littler faster than previous model runs.  From there, models are pretty decent agreement on a piece of the western trough extending far enough south to fully pick up the system & that Michael will be absorbed by the westerlies & upper level trough so as to not hang around any one location for too long while moving northeast.  That's a two-edged sword: the tornado & wind threat will extend well inland but rainfall - while heavy - will not be as extreme as would be the case with a slow moving storm.

So still some question marks as one would expect at this point but clarity is evolving - everyone from Florida to Louisiana & - even on the east coast - should stay up to date on the latest forecasts.

Map below is upper levels (500mb) - European model - noon Tue. showing the stubborn & important high pressure just off the east coast vs. the deep trough over the Western/Central U.S:

The overall pattern through the first 2+ weeks of Oct. favors tropical development over the Atlantic Basin.  The velocity potential anomaly map below indicates expansive green lines - upward motion - spreading from the E. Pacific into the Atlantic Basin, part of a MJO (Madden-Julian Oscillation) pulse.

Note the secondary peak of the hurricane season in mid Oct.:

Meanwhile... Leslie continues to crawl over the Central Atlantic.  Leslie will stay far away from any land areas as the tropical cyclone turns sharply eastward, even south/southeast & moves from the Central into the Eastern Atlantic & could have some impact on the Azores late in the week/weekend.

Atlantic Basin... a strong wave has moved off the coast of Africa but is not likely to be trans-Atlantic....

E. Atlantic:

Mid & upper level wind shear (enemy of tropical cyclones) analysis (CIMMS). The red lines indicate strong shear:

The Atlantic Basin.....

Water vapor imagery (dark blue indicates dry air):

Deep oceanic heat content is seasonably high over the Caribbean, Gulf of Mexico & SW Atlantic as one would expect early in the fall....

Sea surface temp. anomalies:

SE U.S. surface map:

Surface analysis centered on the tropical Atlantic:

Surface analysis of the Gulf:

Caribbean:

The E. Pacific remains active....

"Sergio" has become an annular hurricane well offshore of Mexico with an eye that is some 100 miles across! far to the south/southwest of the Baja but is putting on the brakes & will turn sharply northeast.  Eventually the tropical cyclone - or its remnants - may affect parts of Mexico, the Baja & Southwest U.S. late in the week when a deep upper level trough sets up shop over the Western U.S. & accelerates Sergio to the northeast.

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