784
FXCA20 KWBC 151232
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
831 AM EDT MON MAY 15 2023
PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI FROM MAY
15/12UTC: NEAR NORMAL MOISTURE IS EXPECTED TODAY AND TUESDAY
ACROSS PR/USVI...BUT MOISTURE WILL INCREASE THEREAFTER TO ABOVE
NORMAL LEVELS. TUESDAY APPEARS TO BE THE DAY WITH MOST
INSTABILITY...HAVING AN UPPER TROUGH MOVE IN...CAUSING HIGH LAPSE
RATES IN THE MID LEVELS AND CAUSING A GOOD CHANCE OF
THUNDERSTORMS...THOUGH MOSTLY ACROSS THE NORTHWESTERN QUADRANT OF
PR. BRIEF TRADE-WIND SHOWERS AND AFTERNOON CONVECTION WOULD BE
EXPECTED EVERY OTHER DAY...ALTHOUGH NOT AS UNSTABLE AS
TUESDAY...THE DEEPER MOISTURE EXPECTED ON THE MID TO LATTER PART
OF THE WORKWEEK WILL STILL CAUSE SIGNIFICANT SHOWER ACTIVITY.
THE PRECIPITABLE WATER TODAY AND TUESDAY WILL BE GENERALLY BETWEEN
1.4 AND 1.7 INCHES...WHICH IS NEAR NORMAL FOR THE TIME OF YEAR.
HOWEVER...THE PRECIPITABLE WATER WILL INCREASE ON WEDNESDAY
ONWARD...PEAKING ON THURSDAY AT NEAR 2.2 INCHES. THE 700-500MB AND
850-700MB LAYER RELATIVE HUMIDITY WILL ALSO INCREASE ON WEDNESDAY
ONWARD...SO THE INCREASE IN MOISTURE WILL BE REFLECTED OVER A DEEP
COLUMN. IN THE UPPER LEVELS...THERE IS CURRENTLY A RIDGE WITH AXIS
JUST EAST OF PR/USVI THAT WILL CONTINUE TO MOVE EAST AS AN UPPER
TROUGH APPROACHES FROM THE WEST. THIS WILL CAUSE A GRADUAL
INCREASE IN INSTABILITY OVER PR...WHICH WILL PEAK ON TUESDAY. THIS
INCREASE IN INSTABILITY IS THE REASON WHY HI-RES MODEL GUIDANCE
FAVORS TUESDAY TO HAVE RELATIVELY DEEP CONVECTION AND A BROADER
AREA OF RAINFALL COVERAGE GETTING CLOSE TO AN INCH OF
RAIN...THOUGH MOSTLY ACROSS THE NORTHWESTERN QUADRANT OF PR. THE
UPPER TROUGH WILL MOVE EAST AND ANOTHER RIDGE WILL TAKE ITS PLACE
FROM WEDNESDAY ONWARD. A HIGH PRESSURE ACROSS THE EASTERN
ATLANTIC..AND A SURFACE TROUGH ACROSS THE WESTERN ATLANTIC WILL
CAUSE A SOUTHEASTERLY WIND FLOW ACROSS THE LOCAL ISLANDS THIS
WEEK. HOWEVER...A WEAK HIGH PRESSURE WILL MOVE NORTH OF THE
NORTHEASTERN CARIBBEAN ON TUESDAY...CAUSING MORE ESE WINDS...BUT
WILL RETURN TO SE WINDS ON WEDNESDAY ONWARD.
THIS WEEK...EXPECT AFTERNOON CONVECTION TO CAUSE RAINFALL TOTALS
OF NEAR AN INCH EACH DAY....BUT ISOLATED AREAS COULD RECEIVE OVER
AN INCH OF RAIN. DUE TO THE SE WIND FLOW EXPECTED...MOST OF THE
HEAVIER SHOWER ACTIVITY IS EXPECTED TO OCCUR ACROSS THE NORTHWEST
QUADRANT OF PR. BRIEF SHOWERS CAN BE EXPECTED ACROSS THE USVI EACH
DAY...WITH THE LATTER PART OF THE WEEK CAUSING MORE SHOWER
ACTIVITY ACROSS THE USVI DUE TO THE HIGHER MOISTURE CONTENT.
ALAMO/ACOSTA...WPC (USA)
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