023
FXCA20 KWBC 131154
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
753 AM EDT WED MAR 13 2024
PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI MAR 13/12UTC:
MAINLY FAIR WEATHER...WITH BRIEF ISOLATED TO LOCALLY SCATTERED
SHOWERS CONTINUES TO BE THE FORECAST FOR PR/USVI OVER THE 5-DAY
PERIOD. THE FORECAST SYNOPTIC PATTERN WOULD PROMOTE GENERALLY
STABLE CONDITIONS. THERE ARE A FEW SFC LOW PRESSURE SYSTEMS ACROSS
THE NORTH ATLANTIC...BUT THE TROPICAL ATLANTIC IS DOMINATED BY
HIGH PRESSURE SYSTEMS. THAT SAID...THERE IS A COLD FRONT EXTENDING
FROM THE NORTH ATLANTIC INTO JUST NORTHEAST OF THE NORTHEASTERN
CARIBBEAN...WITH A WEAKENING STATIONARY SECTION JUST NORTH OF
PR/USVI NEAR 21N. THIS WEAKENING STATIONARY FRONTAL BOUNDARY IS
EXPECTED TO DISSIPATE BY THURSDAY. THE MID LEVELS WILL HAVE A
STRONG HIGH PRESSURE FOR THE NEXT FEW DAYS OVER THE LOCAL
AREA...PROMOTING STABILITY. THE UPPER LEVELS WILL HAVE A RIDGE OF
HIGH PRESSURE OVER THE AREA FOR THE NEXT FEW DAYS. HOWEVER...THE
LATEST GUIDANCE DOES SHOW A BRIEF UPPER TROUGH PASSING THROUGH THE
CARIBBEAN LATE FRIDAY INTO SATURDAY...BUT THE MAIN IMPACT WOULD BE
SOUTH OF PR/USVI.
A PERSISTENT TRADE WIND INVERSION IS EXPECTED NEAR THE 850 MB
LEVEL THROUGH MIDDAY THURSDAY. THE TRADE WIND INVERSION WOULD BE
BE WEAKER AND NOT AS PERSISTENT THEREAFTER...BUT THERE IS A BETTER
CHANCE OF AN INVERSION IN THE MORNING HOURS FROM FRIDAY THROUGH
THE WEEKEND. THE AVAILABLE MOISTURE WILL BE BELOW TO NEAR NORMAL
TODAY...WITH PRECIPITABLE WATER NEAR 0.9 INCHES. MOISTURE WILL
GRADUALLY START TO INCREASE TONIGHT AND WILL PEAK ON THURSDAY
EVENING...GOING FROM NEAR 0.9 INCHES THIS EVENING...PEAKING
BRIEFLY AT AROUND 1.6 INCHES ON THURSDAY EVENING...WHICH IS ABOVE
NORMAL. MOISTURE WILL THEN GRADUALLY DECREASE STARTING THURSDAY
NIGHT...WITH PRECIPITABLE WATER VALUES DIPPING DOWN TO 1.2 INCHES
BY FRIDAY EVENING...CONTINUING DOWN TO NEAR 1.0 BY SATURDAY
EVENING...BEFORE ANOTHER INCREASE IN MOISTURE IS FORECAST FOR
SUNDAY. THE RELATIVE HUMIDITY VALUES IN THE 700 - 500 MB LAYER
SHOW A BRIEF PEAK IN MOISTURE LATER ON THURSDAY INTO FRIDAY...BUT
NOT AS PRONOUNCED AS THE TOTAL PRECIPITABLE WATER AND STILL WITHIN
THE NORMAL RANGE...SUGGESTING THAT THE PATCH OF MOISTURE WILL BE
MOSTLY KEPT TO THE LOWER LEVELS.
CONSIDERING THE AVAILABLE MOISTURE THIS WEEK AND STABILITY IN THE
MID LEVELS...THE SHOWER ACTIVITY OVER PR/USVI IS FORECAST TO BE
LIMITED THROUGH THE FORECAST PERIOD...WITH FAIR WEATHER EXPECTED
FOR THE MOST PART. THURSDAY IS FORECAST TO HAVE THE MOST RAINFALL
COVERAGE OUT OF THE NEXT 5 DAYS...COINCIDING WITH THE PEAK IN
AVAILABLE MOISTURE. ALTHOUGH SOME AFTERNOON CONVECTION IS POSSIBLE
ACROSS WESTERN PR EACH AFTERNOON...THE CONVECTION WOULD BE SHALLOW
AND THE MAX AMOUNTS OF RAIN ARE FORECAST TO BE RELATIVELY
MODEST...NEAR 0.25 INCHES OR SO. THE 5-DAY RAINFALL ACCUMULATION
IS FORECAST TO BE NEAR 0.50 TO 0.75 INCHES ACROSS EAST AND
NORTHEAST PR...AS WELL AS PORTIONS OF WESTERN PR. NEAR 0.10 INCHES
ACROSS THE CENTRAL INTERIOR...WHILE SOME AREAS OF SOUTH CENTRAL PR
ARE FORECAST LITTLE TO NO RAIN. THE USVI...VIEQUES AND CULEBRA ARE
FORECAST 0.10 TO 0.50 INCHES.
ALAMO...WPC (USA)
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