THE WEATHER PREDICTION CENTER

COLLEGE PARK, MD


CARIBBEAN FORECAST DISCUSSION




TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
658 AM EDT FRI MAR 24 2017

PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI FROM MARCH
24/06 UTC: AT UPPER LEVELS...A LONG WAVE TROUGH EXTENDS ACROSS THE
WESTERN ATLANTIC TO THE WESTERN/CENTRAL CARIBBEAN. THE LONG WAVE
AXIS IS PRESSING AGAINST THE SUBEQUATORIAL RIDGE TO THE EAST. AS
THE RIDGE YIELDS AND TRADE WINDS CAP WEAKENS...ENVIRONMENTAL
CONDITIONS ARE BECOMING FAVORABLE AND CONDUCIVE TO DEEP
CONVECTION. A SUBTROPICAL JET MAXIMA FLANKING THE TROUGH IS
EXPECTED TO AID WITH THE CONVECTIVE DEVELOPMENT AS IT REPOSITIONS
JUST NORTH OF HISPANIOLA DURING THE DAY TODAY...WITH DIVERGENCE ON
ITS RIGHT ENTRANCE REGION TO PROVIDE FURTHER ENHANCEMENT TO THE
CONVECTIVE DEVELOPMENT. AT LOW LEVELS...THE TROUGH ALOFT SUSTAINS
A SURFACE FRONT ACROSS THE BAHAMAS...WITH PREFRONTAL SHEAR LINE
MEANDERING ACROSS THE DOMINICAN REPUBLIC. IT ALSO FAVORS AN
INDUCED/INVERTED TROUGH THAT EXTENDS NORTH ACROSS PUERTO RICO. THE
TROUGH IS THE FOCUS OF LOW LEVEL MOISTURE CONVERGENCE...AND WHILE
TAKING ADVANTAGE OF ERODING TRADE WINDS CAP IT IS ALLOWING FOR
DEEPER MOISTURE TO POOL ACROSS THE FORECAST AREA...WITH PWAT
CONTENT OF NEARLY TWO INCHES ACROSS THE VI FUELING CONVECTIVE
DEVELOPMENT EARLY THIS MORNING.

AT UPPER LEVELS...THE POLAR TROUGH IS EXPECTED TO SLOWLY WEAKEN
DURING THE WEEKEND WHILE GRADUALLY SHEARING SHORT WAVE ENERGY TO
THE EAST-NORTHEAST OVER THE SUBEQUATORIAL RIDGE. AT MID LEVELS...A
RIDGE UNDERCUTS THE TROUGH FROM THE NORTH...FAVORING FORMATION OF
A CLOSED LOW OVER THE BAHAMAS WHILE ANCHORING A SHORT WAVE TROUGH
OVER THE CARIBBEAN. THE CLOSED LOW IS TO THEN SLOWLY WEAKEN WHILE
LIFTING TO THE EAST-NORTHEAST LATER DURING THE WEEKEND/EARLY NEXT
WEEK. THE DEEP MID LEVEL CIRCULATION WILL HELP SUSTAIN THE
INVERTED TROUGH ACROSS THE FORECAST AREA...AND ON THROUGH SUNDAY
IT EVOLVES INTO A HYBRID CLOSED LOW EAST OF THE TURKS/NORTH OF THE
DOMINICAN REPUBLIC...WITH MID LEVEL FEATURE MAINTAINING ITS COLD
CORE CHARACTERISTICS WHILE THE LOW LEVEL FEATURE EVOLVES INTO A
WARM CORE CYCLONE. AS THE SYSTEM EVOLVES AND AS A SOUTHERLY FLOW
PERSISTS...MOIST PLUME IS TO REMAIN OVER THE FORECAST AREA
THROUGHOUT THE WEEKEND/EARLY NEXT WEEK.

ALTHOUGH THE GLOBAL AND REGIONAL MODEL GUIDANCE GENERALLY AGREE ON
A WET PATTERN ACROSS THE FORECAST AREA...THEY ARE HAVING A HARD
TIME INITIALIZING THE LOW LEVEL MOISTURE CONVERGENCE AND ENSUING
CONVECTION OVER THE VI EARLY THIS MORNING. SO EXPECTING
CYCLE-TO-CYCLE CORRECTIONS TO FORECAST PATTERN AS MODELS RESOLVE
EVOLVING LOW LEVEL CIRCULATION. DURING THE DAY TODAY EXPECTING A
PEAK IN CONVECTION ACROSS PUERTO RICO DURING THE AFTERNOON
HOURS...AS DENSE CI/CS CLOUD COVER EARLY THIS MORNING IS TO DELAY
ONSET OF THE DIURNAL CYCLE. ENVIRONMENTAL CONDITIONS REMAIN RIPE
FOR HEAVY RAINFALL AMOUNTS DURING THE DAY TODAY AND
SATURDAY...WITH A DECREASE IN ACTIVITY ON SUNDAY AS THE LOW LEVEL
CIRCULATION STRENGTHENS TO THE NORTH.

JIMENEZ...IMN (COSTA RICA)
SUBRATH-ALI...TTMS (TRINIDAD AND TOBAGO)
DAVISON/GALVEZ...WPC (USA)





Last Updated: 658 AM EDT FRI MAR 24 2017