• Tracking the Tropics With Mike: tropical storm Dorian moving steadily westward

    By: Michael Buresh

    Updated:

    Aug. 25, 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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    Tropical wave '98-L' is now fully over the Western Atlantic east of Florida & a little north of the Bahamas.  Thunderstorms continue to pop, especially over the eastern part of the circulation.  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 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 northeast onshore flow/wind will continue through Sunday as the low organizes.  

    At the surface.... low pressure is east of Jacksonville & is moving more northeast so is headed over the warm far Western Atlantic & Gulf Stream. Heavy showers & t'storms are mostly east & northeast of the "center" which may jump around a bit trying to couch under the strongest convection.  An upper level trough to the north has become the main steering mechanism taking the low - could become "Erin" -well east of the U.S. east coast  & west & northwest of Bermuda.  Other than a rip current risk along the U.S. east coast, so major direct impacts are expected despite what is likely to be a strengthening tropical system.

    Spaghetti model forecasts for '98-L' & t.s. "Dorian":

    Meanwhile... Chantal has dissipated over the North Atlantic as low pressure has moved inland near the Texas/Louisiana border.  An upper level disturbance remains near the Gulf Coast & just offshore of Louisiana.  While significant surface development is not likely, heavy rain will continue over parts of Louisiana & further east through the week as the upper level disturbance moves east.

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

     

     

    Over the Central Atlantic.... "little" tropical storm Dorian continues to move steadily westward with limited structural organization evident on satellite data.   Gusty winds & squalls reach the Windward Islands of the Caribbean as early as late Monday where tropical storm WATCHES & WARNINGS are in effect for some islands.  The official NHC forecast does take Dorian to a hurricane while traversing the NE Caribbean but overall conditions (shear & especially dry air) look marginal which may very well result in weakening.  As a whole, Dorian has generally trended west without gaining much latitude despite forecast's models insistence on a more poleward movement.  A weaker system is likely to track more west vs. any kind of northward move.  The overall marginal atmospheric conditions + possible land interaction should limit Dorian's intensity later in the week.  It's worth noting that Dorian is a small/compact system & therefore may be susceptible to even small changes in its environment (shear/ dry air/land) resulting in wide intensity swings over a short period of time.  In any case.... anyone with travel plans to the Caribbean through the 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.  Dorian will encounter a good deal of dry air in the coming days.

    2019 names..... "Erin" 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 with dissipation likely soon.

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