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FXCA20 KWBC 161250
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
750 AM EST THU NOV 16 2023
PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI NOV 16/12UTC:
GENERALLY FAIR WEATHER IS EXPECTED TODAY...BUT THE CHANCES OF
SIGNIFICANT RAINFALL WILL INCREASE WITH EACH PASSING DAY INTO THE
WEEKEND...AS AN AREA OF DISTURBED WEATHER REACHES THE GREATER
ANTILLES. SUNDAY INTO MONDAY THE AMOUNT OF RAIN IS EXPECTED TO
GRADUALLY DECREASE. THE AVAILABLE MOISTURE WILL FOLLOW THE SAME
PATTERN...WITH BELOW NORMAL MOISTURE EXPECTED TODAY...BUT
GRADUALLY INCREASING ON FRIDAY...GETTING TO ABOVE NORMAL LEVEL ON
SATURDAY INTO SUNDAY...THEN DECREASING INTO THE NORMAL LEVELS BY
MONDAY. FOR TODAY...NOT ONLY IS THERE DRIER THAN NORMAL
MOISTURE...BUT A MID LEVEL RIDGE IS PROMOTING STABILITY AND IS
LOOSELY ASSOCIATED WITH A TRADE WIND INVERSION THAT WILL PERSIST
NEAR THE 800-900MB LEVELS THROUGH VERY LATE TONIGHT INTO EARLY
FRIDAY MORNING. THIS COMBINATION IS WHAT WOULD CAUSE THE GENERALLY
FAIR WEATHER EXPECTED TODAY ACROSS PR/USVI. THAT BEING SAID...THE
MAIN STORY IS THE AREA OF DISTURBED WEATHER ASSOCIATED WITH A
BROAD LOW PRESSURE OVER THE SOUTHWESTERN CARIBBEAN. AS THE
DISTURBANCE COULD STRENGTHEN AS IT MOVES THROUGH RELATIVELY
FAVORABLE ENVIRONMENTAL CONDITIONS. IT WILL ALSO INTERACT WITH AN
APPROACHING UPPER TROUGH UNDER FAVORABLE MJO CONDITIONS FOR HEAVY
PRECIPITATION. AS THE UPPER TROUGH MOVES WEST...THIS WILL ORGANIZE
A MOIST PLUME FROM THE SOUTHWEST CARIBBEAN INTO THE GREATER
ANTILLES...THAT WILL LIKELY CAUSE SIGNIFICANT PRECIPITATION OVER
SOUTHERN PUERTO RICO DURING THE WEEKEND...THEN POSSIBLY THE USVI
LATE IN THE WEEKEND INTO EARLY NEXT WEEK.
AS MENTIONED ABOVE...THE AVAILABLE MOISTURE IS FORECAST TO BE
BELOW NORMAL TODAY THEN INCREASE BEFORE EARLY ON FRIDAY. IN TERMS
OF PRECIPITABLE WATER...THE LATEST GUIDANCE IS SUGGESTING IT WILL
BOTTOM OUT AT NEAR 1.1 INCHES THIS MORNING...THEN MAX OUT NEAR 2.5
INCHES LATE SATURDAY NIGHT. IN TERMS OF PRECIPITATION...EXPECT
LITTLE RAINFALL TODAY...THEN A NOTICEABLE INCREASE IN RAINFALL
ACTIVITY STARTING ON FRIDAY...WHEN EXPECT MAXIMA NEAR 1.25 INCHES
IN SOUTHEAST PUERTO RICO INTO EARLY SATURDAY MORNING. ON
SATURDAY...UNDER THE INFLUENCE OF MOIST SOUTHERLY FLOW...EXPECT
CONVECTION IN THE SOUTHERN HALF OF PUERTO RICO ALL DAY...TO
PRODUCE ISOLATED AMOUNTS NEAR 2 INCHES ACROSS SOUTH-CENTRAL PUERTO
RICO...WITH LESSER AMOUNTS ELSEWHERE. ANOTHER DAY WITH SIGNIFICANT
RAIN WOULD BE SUNDAY...WHERE OVER 1.5 INCHES OF RAIN ARE POSSIBLE
ACROSS THE SOUTH TO SOUTHWESTERN SECTIONS OF PR. THE SHOWER AND
THUNDERSTORM ACTIVITY COULD MOVE EAST BY MONDAY...WITH THE HIGHEST
AMOUNTS OF RAIN....NEAR 1 INCH NEAR THE USVI. HOWEVER...THE GLOBAL
MODELS START TO DISAGREE SIGNIFICANTLY BY SUNDAY AND MONDAY...SO
CONFIDENCE IS LOW.
THE 5-DAY TOTAL RAINFALL FORECAST IS TO REACH 3-4 INCHES IN MOST
OF SOUTHERN PUERTO RICO...ACCUMULATING PARTICULARLY FROM FRIDAY
THROUGH SUNDAY. THE USVI COULD OBSERVE 1 - 1.5 INCHES THROUGH THE
5-DAY PERIOD.
ALAMO...WPC (USA)
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