• Talking the Tropics With Mike: Hurricane Humberto, tropical storm Imelda & tropical depression #10

    By: Michael Buresh

    Updated:

    Sept. 17, 2019 - The "Buresh Bottom Line": Always be prepared!.....First Alert Hurricane Survival Guide... City of Jacksonville Preparedness Guide... Georgia Hurricane Guide.  

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    ATLANTIC BASIN "HOT SPOTS":

    (1) hurricane Humberto - hurricane WARNING for Bermuda

    (2) tropical depression #10 over the Central Atlantic

    (3) tropical storm "Imelda" over the extreme NW Gulf of Mexico

    (4) parade of tropical waves from the Eastern Caribbean to Africa.......

    HURRICANE HUMBERTO:

    There will be no inland local impacts from Humberto but the combination of Humberto well to the east & high pressure to the north will result in a continuation of dangerous conditions at our (Fl./Ga. & much of east coast & Bahamas) beaches.  Rough seas & surf will only slowly subside & a very high rip current risk will continue much of this week.

    Tropical depression #9 was upgraded late Friday afternoon... to tropical storm Humberto late Fri. evening... & to a hurricane Sunday evening - while east of Florida & north of the Bahamas.  The storm continues to organize & strengthen with a broad eye that's becoming more & more symmetrical. 

    Overall conditions look favorable for strengthening into Wed. & Humberto could become a Cat. 3 while turning sharply to the east/northeast & - by midweek - accelerating away from the U.S.  There look to be some impacts on Bermuda mid to late week where a hurricane WARNING has been issued.  Hurricane hunter aircraft have found an ever widening wind field.

    The positioning & strength of the Bermuda high over the Atlantic plus an incoming upper level trough over the Northeast U.S. is again (like Dorian) playing an important role in the track. 

    Sunday afternoon - at about 30-35,000 feet - there was a weakening trough will be over New England while the Bermuda high starts to strengthen over the Central Atlantic & the upper low over the Gulf "peels" away to the west.  This essentially leaves an alleyway over Fl. giving Humberto an "out" well to the east of Fl.  After a brief "rest" or stutter/wobble to the north or even northwest while northwest of Bermuda, Humberto will resume its northeast movement while accelerating to the N. Atlantic.

    Ensemble model forecasts for Humberto show a nice shift east:

    TROPICAL DEPRESSION #10:

    #10 formed from an African tropical wave that's been moving steadily - though slowly - west/northwest.  The depression should pretty quickly become a tropical storm ("Jerry")... & eventually a hurricane.  Though uncomfortably close by Fri. into the weekend to Puerto Rico, present indications are that #10 will be north of the Greater Antilles.  However, all the folks in the Caribbean nations/islands need to stay up to date on the latest forecasts.  Beyond this weekend, EARLY indications are that #10 turns more northward but whether or not the tropical cyclone makes a full (harmless) turn to the north & stays out to sea is still something to be carefully watched.  The Bermuda high looks to be re-strengthening late in the month, so #10 may not necessarily be a "clean up & out".  And if #10 does end up recurving there's other tropical trouble to follow (see below).

    Recent global model forecast trends are farther west next week likely due to a combination of a weaker system initially being more steered by the low level prevailing easterlies & the strengthening of the Bermuda high to the north.  Do stay tuned.

    TROPICAL STORM IMELDA:

    A wider view of the Gulf/SW Atlantic shows Humberto as well as an upper low over the Gulf of Mexico that helped spawn a surface low over the Northwest Gulf quickly leading to the development of tropical storm Imelda.  Luckily... time is running out for more significant development as Imelda made landfall at Freeport, Texas about 2pm EDT with sustained tropical storm force winds verified by several coastal reporting stations.  Very heavy rain & flooding will plague coastal SE Texas as far inland as Houston & College Station.

    CENTRAL & EASTERN ATLANTIC:

    There are a several active tropical waves over the Central & East Atlantic that will likely develop with long term track the big question mark (of course!).  Plenty of time to watch/monitor/track & "cipher".  Most of the more reliable global forecast models - European/GFS/UKMET - are bouncing around on development not to mention the location, but the Northeast Caribbean may be faced with another named storm (#10) this week & yet again possibly the following week.  Also of interest.... a lead wave that had been weakening has now flared with some disorganized t'storms recently while moving into the Eastern Caribbean - something to keep an eye perhaps over the Caribbean &/or Gulf of Mexico by the weekend into next week. And there are multiple strong tropical waves moving off the coast of Africa with at least one likely to develop by the weekend or shortly therafter.

     

     

    An examination of dust over the Atlantic shows generally less dust over the basin vs. past months which is fairly typical for September & the peak of the hurricane season. Much too much is made of the dust & tropical cyclones.  It's not all uncommon for tropical waves to simply "wait out" the dry air & dust organizing once the wave is clear of the dry atmosphere.

    2019 names..... "Jerry" & "Karen" are next on the Atlantic list (names are picked at random... repeat every 6 years... historic storms are retired (Florence & Michael last year) & Dorian is almost certain to be next:

     

    East Atlantic:

    Mid & upper level wind shear (enemy of tropical cyclones) analysis (CIMMS). The red lines indicate strong shear of which there is plenty across the Atlantic at the moment:

    The Atlantic Basin:

    Water vapor imagery (dark blue indicates dry air):

    Deep oceanic heat content:

    Sea surface temp. anomalies show a warm Gulf of Mexico, Central & Northwest Atlantic while the "Main Development Region" (MDR) remain cooler than avg.  Note the upwelling (cooler water) left behind Dorian near the Bahamas (though starting to "mix out"):

    While the MDR is cooler than avg., it's important to realize the water is still warm enough to support tropical systems....

    SE U.S. surface map:

    Surface analysis centered on the tropical Atlantic:

    Surface analysis of the Gulf:

    Caribbean:

     

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