SPECIAL TROPICAL WEATHER FORECAST SYNOPSIS….AREA OF DISTURBED WEATHER OVER THE CARIBBEAN SEA…ISSUED MAY 04, 2015…11:40 A.M. EDT

SEVERE WEATHER RISK: SLIGHT
TROPICAL STORM FORMATION:  LOW

ALL forecasts contained on this site,  are based on my analysis and knowledge of various forecast tools, including information contained in NHC products, and are not copies from any other entity.

This office is now switching to Tropical Weather Forecast mode.  I will try, if time allows, to include severe weather, however, the added analyses would consume more time than I’d prefer, making my synopsis post later in issuance.  Please refer to the Storm Prediction Center website home page for severe weather information in the interim.

SPC HOME PAGE GRAPHIC (LINKED)
activity_loop

Analysis of Global models, and the regional NAM still indicate some type of probable sub-tropical development occurring, north of the Bahamas by Wednesday.  The NHC has kept a LOW (30%) probability of development over the NW Bahamas in the 5 day graphical TWO.  I concur with the current probability, however based on analysis of the most recent model runs, and persistence shown, I would not be surprised if the NHC increases the probability to medium within the next 48 hours.

NHC 5 DAY GRAPHICAL TROPICAL WEATHER OUTLOOK
two_atl_5d1

Models are suggesting a SUBTROPICAL low at the moment.  Should this development occur, the main characteristic with it will be a transition to warm core, albeit probably shallow.  The one main characteristic which suggests this being subtropical in nature, is the maximum sustained wind field will be removed from near the center of circulation.  At the moment, the forecast suggests minimal tropical storm force conditions (in this case, subtropical storm).  Should this attain sustained winds of 39 mph, shows some persistent convection and a shallow warm core, then it will be christened ANA.  Based on the current Zonal Wind Shear forecast from the GFS and CMC models, upper level winds are still forecast to be somewhat slightly conducive.  Given this, and the forecast slow movement of this possible system, I will not fully rule out a very slim possibility of a transition to a Tropical System just immediately prior to landfall, if landfall occurs.

GFS / CMC ZONAL SHEAR FORECAST
GFS.ZONAL850200ushear15

CMC.ZONAL850200shear25

The following maps are from the recent model runs.  The ECMWF solution shows a weaker system, remaining offshore, however before dissipation, suggests more of a west component to the feature.  The other Global Models,  as well as the regional NAM and DGEX indicate a land falling system from between GA to NC.  I will touch on this after the graphics.

ECMWF
ECMWF
GFS
GFS
CMC
CMC
NAVGEM
NAVGEM
FIM 9 SEUS
wind_10m_f108

NAM
NAM
DGEX
DGEX

This system should be somewhat of a slow mover, as riding is forecast to be in place north of it, during the next 5 – 6 days.  Current indications are, the system will be on the eastern side of the ridge axis, which to me would seem to imply a more westward component to the system.  The current steering layers forecast, in which at this time there is only one available (GFS) from the PSU e-WALL site, indicates an initial northward motion, and as we move closer to Friday, more of a motion to the NNW.  The ECMWF is the only model keeping this offshore, as of this mornings analysis.  Albeit the ECMWF by virtue is usually the better performer, I cannot safely rule out the solutions of the other global models and the regional NAM and DGEX.  My reasoning behind this is, in addition to the forecast steering, analysis of some of the 850 mb height maps, and 1000 – 500 mb thickness (noted in the above graphics) indicates some slightly higher height rises north and east of the system, which would in fact allow it to head more toward the NNW to NW.  Again, it is still a wait and see until a solid, closed surface circulation can be identified, and models can latch on to it.

CMC 850 MB HEIGHTS
CMC.850
GFS 850 MB HEIGHTS
GFS 850 HEIGHTS
Analysis of visible satellite loop imagery seems to suggest a large area of disturbed weather, associated currently with an elongated surface trof extending from Cuba down to Nicaragua, is developing near 22.0N;83.0W, and is currently stationary.  At the moment, it’s not exactly clear if this is the beginning of the system, but is the only region at the moment showing cyclonic turning.

WESTERN ATLANTIC VIS SATELLITE STILL
vis-l

WESTERN ATLANTIC VIS SATELLITE LOOP
2vis-l

SSEC GEOSTATIONARY EASTERN SATELLITE LOOP
latest_east_vis_conus

Residents from GA to NC should monitor this situation over the next 96 hours, in the event Tropical Storm Watches and /  or Warnings are initiated later in the week.  I’m not looking for any significant damage or such, however heavier rainfall could cause some isolated inland flooding, especially in low lying areas, along with some probable minor coastal flooding, and minor beach erosion at high tide.  Again, these are just some possible scenarios which may be associated with this probable system.  NHC and NWS statements should be followed by residents that could be affected by this.

I should have another update tomorrow, but will not be available again until Friday.

Have a blessed day!

T. F. “STORM” WALSH III GMCS, USCG (ret)
METEOROLOGIST / HURRICANE SPECIALIST / SEVERE WEATHER SPECIALIST MEMBER WEST CENTRAL FLORIDA AMS
CoCoRAHS OBSERVER    

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About palmharborforecastcenter

I am a Tropical Forecast meteorologist, providing hurricane forecasts during the Atlantic Hurricane Season. I retired from the U.S. Coast Guard in July of 2001. Meteorology became my passion in high school, and I have continued my educational background in meteorology since 1996, when I undertook the study of Tropical Meteorology. While working toward my degree, I had to unexpectedly withdraw from college due to my oldest sons medical reasons. I do however, meet the educational criteria of the AMS to be recognized as a meteorologist. Studies include, but are not limited to the Navy Aerographers Mate course, Naval METOC meteorology course, Meteorology 2010 Sophomore level course while attending St. Petersburg College, Clearwater, FL., Basic Forecasting course for operational meteorologists from Rapid WX, meteorology institute, a four month meteorological internship, and extensive research on numerous meteorological topics such as the MJO, NAO, satellite imagery interpretation, etc. I have been forecasting Tropical Weather (Tropical Storms and Hurricanes) since 1996, with my main client being three different Coast Guard Commands.
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