POSSIBLE W. CARIBBEAN SEA / GOMEX AREA DEVELOPMENT FORECAST SYNOPSIS…ISSUED MAY 20, 2018…8:50 P.M. EDT

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(T. F. “Storm” Walsh III)

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Good evening everyone!

Based on my evening analysis, the majority of Global models (ECMWF, GFS, CMC GEM, FIM8, NAVGEM, and NASA GEOS) are still in agreement of possible sub-tropical development just north of the W. Caribbean Sea, to the central to north central GOMEX.  Both the GFS and ECMWF MSLP Normalized Anomaly maps have been indicating lowering of surface pressures over the W. Caribbean for the past 3-4 days, and continue to indicate the same.  The following forecast maps are from each of the models mentioned, and show MSLP (Mean Sea Level Pressure),and now suggest slow development beginning in 4 – 5 days.

ECMWF

GFS

CMC

FIM

NAVGEM

NASA GEOS
Probability forecast models have increased the probability of tropical development, with the ECMWF EPS indicating the probability of a Tropical Depression, just prior to the supposed system coming ashore.

NCEP MULTI MODEL

ECMWF EPS

With the consistency of ALL of the models, forecast PWAT, favorable 200 mb vertical velocities indicating strong upward motion over the area from now until around the 25th – 26ty of this month, development cannot be ruled out at this time.

PWAT FORECAST

200MB VELOCITY POTENTIAL ANOMALIES (BLUE CONTOURS ARE FAVORABLE)

I do believe this will be slow to occur, and based on satellite loop imagery, a surface low appears to be trying to take shape (note the counter-clockwise spin in the low cloud deck). 

RAMSDIS AND GOES 16 SATELLITE LOOP IMAGERY (CLICK GRAPHICS FOR ANIMATION)

Based on everything analyzed this evening, my thoughts at this particular point and time, are that the area in the Caribbean at the moment, in satellite imagery will begin to move northward.  Over the course of the forecast period, upper level winds are forecast to become a little more favorable, however, not optimal.  Although upper level winds are forecast to relax somewhat, the forecast is for an outflow channel to be only to the NE and east of whatever may develop.  This indicates to me we will see another east weighted system, in that the strongest wind and precipitation will be east of the low center.  The forecast wind field, showing the strongest winds away from the “center”, along with analysis of simulated satellite loop analysis, suggests if this area does develop, it most likley will be sub-tropical in nature.  Until we get further into the period, it appears this “could” be depression to weak STS status prior to coming ashore.

WIND SHEAR FORECAST (OUTFLOW CHANNEL SHOWN BY ARROWS)

Based on the current available model runs, some of the modeling (GFS, NAVGEM, FIM) indicates whatever we may see, could cross the Florida peninsula, and other global models indicate more of a northward motion and a range from the W. FL. Panhandle, to Louisiana.  Once again, I WILL REITERATE, it’s too early to focus on a direction or track, until we see something better organized and a closed surface low, as the modeling is picking up on the heat energy which is over a broad, elongated area.  Once we see a closed surface low, at least with one closed isobar, the energy will be “focused’ more tightly, and the models will have something to latch onto, making their forecast motion more accurate.

Based on analysis of the current forecast steering layers maps, valid for 00Z 21 May, I prefer the ECMWF forecast position at the moment, as the steering forecast right now, doesn’t show anything allowing for an eastward movement.  This too however, can change over the next few days.

I will be in between jobs next week, and don’t know what my possible new work schedule may look like.  I will continue to monitor the W. Caribbean, and will have updates when possible.

Have a blessed evening!

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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