• Talking the Tropics With Mike: Tropical depression #5 forms over Central Atlantic

    By: Michael Buresh

    Updated:

    Aug. 24, 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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    The peak of the hurricane season is essentially here.  Two-thirds of all Atlantic hurricanes occur between Aug. 20th & Oct. 10th with the exact peak on September 10th.

    The tropical story through the weekend - stay up to date on the latest developments/forecasts! - continues to be tropical wave '98-L' meandering over/near Fl. through Sat. evening before moving northeast & gradually accelerating offshore.  Rip currents along area beaches are the biggest threat & should not be taken lightly - always swim & surf with a "buddy" & as close to a lifeguard as at all possible.

    Impacts on Jacksonville/NE Fl./SE Ga.:

    * NO significant impacts through the weekend but.......

    * a little bit of a bump in seas & surf so an increase in the rip current risk - especially Sat. through Sunday - use caution if going into the water at area beaches.

    * a decent easterly/northeast onshore flow/wind will develop through Sunday as the low organizes.  Most of the development will be offshore to the east of Fl. when the system could very well become "Dorian".

    * Little significant rain for NE Fl./SE Ga. directly from the disturbance.  Most of the real heavy rain will be east of the center &, therefore, east of most of Fl. except - at times - for SE & extreme East Central Fl.

    * the disturbance will be moving away by late Sunday reducing already minimal impacts even more.

    At the surface.... low pressure is slowly shifting northward near the east coast of Florida. Disorganized but heavy showers & t'storms are mostly east & northeast of the "center".  Proximity to land + a fair amount of shear should inhibit much in the way of development through early Sunday as the low slowly shifts/moves offshore.  By Sunday, the low will be east & northeast of Jacksonville moving northeast where there appears to be the best "bet" for organization/intensification as the low accelerates northeast as an upper level trough to the north becomes the main steering mechanism.  This would mean few problems/impacts for Jacksonville & Fl. outside of an increase in seas & a refreshing northeast breeze later Sat. into Sunday.  At this time, the forecast is for the low to stay east of the U.S. east coast at its strongest intensity (possibly even as a hurricane!) but close enough to the Carolina's Sunday to produce gusty winds & serious rip currents.  From the early to middle part of next week the system will move over the Western Atlantic east of the U.S. coastline & west & northwest of Bermuda.

    Spaghetti model forecasts for '98-L' & t.d. #5:

    Meanwhile... Chantal has dissipated over the North Atlantic but - wait - there's more!

    Another area to watch through the weekend will still be the Northwestern Gulf of Mexico.  A pretty decent tropical wave plus an upper level disturbance has led to the gradual development of a surface low & is moving northward into & over the Northwest Gulf where there has been some pulsing - impressive at times - convection.  While models show only weak surface development - if any at all - this will be an area to watch for "sneaky" development in an area - historically speaking, the Western Gulf  - that is highly favored in mid to late Aug. with water that is plenty warm along with low shear.  Heavy rain will occur over far SE Texas & Southern Louisiana.  Since only a short distance offshore with a short track to reaching land near the Texas/Louisiana border, it appears the low will run out of time before the system can realize its full potential.  But it's a situation to watch from Galveston, Tx to near New Orleans.

    Rainfall forecast shows the tropical "trouble spots" receiving heavy rain (W. Atlantic & NW Gulf).

     

     

    There are also a couple of tropical waves between the Caribbean & Africa.  One of the lead waves has been upgraded to tropical depression #5 several hundred miles to the east of the Lesser Antilles & has the potential to become a tropical storm upon approach to the islands.  Thereafter, conditions - possible land interaction + increasing shear - become more marginal to maintain &/or intensify a tropical system.  But gusty winds & squalls reach the Windward Islands of the Caribbean as early as Tuesday.  The official NHC forecast does take t.d. # 5 to a hurricane while traversing the NE Caribbean by the middle of next week. It's worth noting that t.d. five is a pretty small system & therefore may be rather susceptible to even small changes in its environment (shear & dry air especially).  In any case.... anyone with travel plans to the Caribbean through next week should stay up to date on the latest forecasts.

    An examination of dust over the Central & Eastern Atlantic shows a continuation of a good deal of dust over the Central & Eastern Atlantic as well as parts of the Caribbean.  While such dry air can inhibit tropical development initially, once any waves are farther west or if the wave can stay a little south & out of the dust "cloud" - & IF all other conditions are equal - organization/strengthening can occur.  The 2005 hurricane season stands out (along with several other seasons) as a "dusty" Eastern Atlantic but disturbances simply waited to get out of the dust - further to the west - to develop & then "make history".

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

     

    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. along with parts of the Central Caribbean.....

    SE U.S. surface map:

    Surface analysis centered on the tropical Atlantic:

    Surface analysis of the Gulf:

    Caribbean:

     

    Over the East Pacific.... "Ivo" is battling shear & cooler water which is causing pretty fast weakening through the weekend west of the Baja of California.

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