Skip Navigation Links weather.gov 
NOAA logo - Click to go to the NOAA homepage National Weather Service   NWS logo - Click to go to the NWS homepage
The Weather Prediction Center
 
Tropical Discussion
 
(Caution: Version displayed is not the latest version. - Issued 1055Z Apr 06, 2020)
 
Version Selection
Versions back from latest:  0   1   2   3   4   5   6   7   8   9   10   
 
Abbreviations and acronyms used in this product


TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
655 AM EDT MON APR 06 2020

PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI FROM APR 06/11
UTC: MID/UPPER LEVEL RIDGE TO THE WEST REMAINS THE DOMINANT
FEATURE OVER THE GULF OF MEXICO INTO THE EASTERN USA...WHILE
FARTHER EAST A BROAD TROUGH DOMINATES THE FLOW OVER THE WESTERN
ATLANTIC. THE LATTER BOTTOMS OUT OVER THE NORTHEAST CARIBBEAN
ISLANDS...WITH MID LEVEL SHORT WAVE VORTICES ROUNDING THE BASE OF
THE TROUGH STREAMING ACROSS THE FORECAST AREA FROM TIME-TO-TIME.
AT LOW LEVELS...THE TROUGH ALOFT SUSTAINS A MEANDERING FRONT THAT
TRAILS ACROSS THE ATLANTIC TO JUST NORTH OF THE FORECAST AREA.
ALSO...UNDER THE INFLUENCE OF THE BROAD POLAR TROUGH NORTH OF THE
ISLANDS...AN INDUCED/INVERTED TROUGH EXTENDS THE CENTRAL
CARIBBEAN. THIS...IN-TURN...SUSTAINS A MOIST SOUTHEASTERLY FLOW
ACROSS THE ISLAND CHAIN THAT IS POOLING OVER THE FORECAST AREA AS
IT CONVERGES ALONG THE MEANDERING SURFACE FRONT. THE PWAT CONTENT
REMAINS AT 1.50 INCHES...WHICH IS 125 PERCENT OF NORMAL AS
INDICATED BY RAMSDIS ESTIMATES. THE BOUNDARY LAYER FLOW IS FROM
THE EAST-NORTHEAST...WHILE THE LOW-MID LEVEL STEERING FLOW RETAINS
A WESTERLY COMPONENT. THIS IS RESULTING IN WEAK VERTICAL SHEAR
THAT IS ENHANCING DIURNAL DEVELOPMENT OVER THE FORECAST AREA.

GLOBAL MODELS HAVE REACHED A CONSENSUS ON HOW MID/UPPER LEVEL
PATTERN IS GOING TO EVOLVE AND ITS IMPACT OVER THE FORECAST
AREA...EXPECTING CURRENT PATTERN TO HOLD THROUGH THURSDAY
AFTERNOON WITH THE TROUGH ALOFT TO HOLD ITS GROUND OVER THE
WESTERN ATLANTIC INTO THE NORTHEAST CARIBBEAN. MID LEVEL VORTICES
ARE TO CONTINUE ROUNDING THE BASE OF THE TROUGH...WITH MODELS
SHOWING AN INCREASE ON WEDNESDAY/THURSDAY WHEN STRONGER VORTICES
STREAM ACROSS THE FORECAST AREA. LATER IN THE WEEK...PATTERN
UNRAVELS...WITH MID LEVEL RIDGE BUILDING EAST ACROSS THE NORTHERN
CARIBBEAN TO DISPLACE THE POLAR TROUGH. ENVIRONMENTAL CONDITIONS
ARE TO THEN GROW MORE HOSTILE TO CONVECTION AS TRADE WINDS
INVERSION STRENGTHENS. AT LOW LEVELS...MEANDERING FRONT IS TO
PERSIST THROUGH THURSDAY MORNING...THEN RAPIDLY FRONTOLIZE ON
FRIDAY. PWAT CONTENT OF 1.50-1.75 INCHES IS TO THEN EBB...WITH A
DRYER AIR MASS ENVELOPING THE NORTHEAST CARIBBEAN ISLANDS LATER IN
THE WEEK.

THE HIGHER THAN NORMAL MOISTURE CONTENT IS TO CONTINUE FUELING
DIURNAL CONVECTION OVER THE FORECAST AREA DURING THE NEXT FOUR
DAYS...WITH MOST ACTIVE INITIALLY BUILDING OVER INTERIOR PORTIONS
OF PUERTO RICO DURING THE LATE MORNING INTO THE AFTERNOON HOURS.
AS THE WEAK WEST-SOUTHWESTERLY STEERING FLOW HOLDS...THIS COULD
ONCE AGAIN DRIVE ACTIVITY BUILDING TO THE WEST ACROSS THE SAN JUAN
METRO AREA LATER THIS AFTERNOON INTO THE EVENING HOURS. HIGHER
RISK OF THIS HAPPENING IS EXPECTED TODAY...WHILE ON TUESDAY THE
RISK IS LOWER AS THE STEERING FLOW BECOMES SOMEWHAT ILL ORGANIZED.
THE THREAT OF HEAVY RAINFALL IS EXACERBATED ON WEDNESDAY-THURSDAY
AS STRONGER MID LEVEL VORTICES ROUNDING THE BASE OF THE MID LEVEL
TROUGH STREAM ACROSS THE FORECAST AREA.

DAVISON...WPC (USA)
GALVEZ...WPC (USA)