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FXCA20 KWBC 311236
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
836 AM EDT WED MAY 31 2023
PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI FROM MAY
31/12UTC: THE LATEST GUIDANCE CONTINUES TO SUGGEST THAT EASTERN PR
WILL HAVE A CHANCE OF SHOWERS FOR THE NEXT 5 DAYS UNDER A SE WIND
FLOW. THE AVAILABLE MOISTURE WILL DECREASE SLIGHTLY
TODAY...REMAINING NEAR NORMAL INTO TOMORROW. BY THURSDAY EVENING
ONWARD...THE PRECIPITABLE WATER WILL INCREASE TO ABOVE NORMAL
LEVELS...WITH VALUES POSSIBLY SURPASSING 2 INCHES. AFTERNOON
CONVECTION ACROSS NW-PR IS POSSIBLE EACH AFTERNOON BUT THE AMOUNTS
OF RAIN MAY BE MODEST THROUGH THE REST OF THE WEEK DUE TO THE LACK
OF DYNAMICS. HOWEVER...THERE IS SOME INDICATION THAT AN INCREASE
IN INSTABILITY IS POSSIBLE OVER PR FOR THE WEEKEND. THE USVI WILL
OBSERVE SCATTERED SHOWERS EACH DAY...LEAVING A FEW HUNDREDTHS OF
AN INCH OF RAIN FOR THE MOST PART. HOWEVER...THE INCREASE IN
MOISTURE IN THE LATTER PART OF THE FORECAST PERIOD MAY CAUSE AN
INCREASE IN RAINFALL OVER THE USVI.
A SURFACE HIGH PRESSURE ACROSS THE EAST TROPICAL ATLANTIC AND A
COUPLE OF WEAK SFC LOWS ACROSS THE CENTRAL TO EASTERN
ATLANTIC...ALONG WITH A DEVELOPING SFC LOW ACROSS THE SOUTHWESTERN
ATLANTIC...ARE CAUSING SE WINDS OVER THE LOCAL ISLANDS. THE WIND
DIRECTION WILL BECOME ALMOST SOUTHERLY BY FRIDAY AND THROUGH THE
WEEKEND AS A SURFACE LOW CONTINUES TO DEVELOP NORTH OF THE LOCAL
ISLANDS AND MOVES EAST. THIS SURFACE LOW WILL BRING MOISTURE FROM
THE SOUTH AND WILL CAUSE THE PRECIPITABLE WATER TO INCREASE TO
ABOVE NORMAL LEVELS FROM FRIDAY AND THROUGH THE WEEKEND. THERE ARE
RIDGES IN THE MID AND UPPER LEVELS OVER THE LOCAL ISLANDS...WHICH
ARE EXPECTED TO REMAIN FOR THE NEXT SEVERAL DAYS. MID AND UPPER
LEVEL TROUGHS ACROSS THE WESTERN CARIBBEAN WILL WEAKEN BEFORE
GETTING CLOSE TO THE LOCAL ISLANDS. HOWEVER...THE LATEST EGDI
ALGORITHM IS SUGGESTING THAT THE WEAKENING UPPER TROUGH...CAUSING
UPPER LEVEL DIVERGENCE...COMBINED WITH THE DEEP TROPICAL MOISTURE
WILL CAUSE AN INCREASE IN SHOWER AND THUNDERSTORM ACTIVITY OVER
THE GENERAL AREA FROM FRIDAY INTO THE WEEKEND. HOWEVER...THE MODEL
RAINFALL FORECASTS ARE NOT IMPRESSIVE FOR WESTERN PR...BUT DECENT
FOR EASTERN PR WITH ONSHORE FLOW FROM THE SSE. THE LACK OF HIGH
RAINFALL VALUES IN THE FORECAST ACROSS WESTERN AND NORTHWESTERN PR
COULD BE TO CLOUDINESS THAT IS EXPECTED...BUT THE LOW LEVEL
CLOUDINESS GUIDANCE STILL SUGGESTS SOME LOCALIZED
CONVECTION...THEREFORE THERE IS SOME RAINFALL IN THE FORECAST
ACROSS NORTHWESTERN PR THROUGH THE WEEKEND...THOUGH NOT AS MUCH AS
E-SE PR. THE USVI...SHOULD ALSO SEE AN INCREASE IN SHOWER ACTIVITY
WITH THE INCREASE OF MOISTURE.
THE AMOUNTS OF RAIN ARE FORECAST TO BE GENERALLY UNDER A HALF AN
INCH FOR EASTERN PR THROUGH THURSDAY...BUT RAINFALL TOTALS ARE
EXPECTED TO INCREASE ON FRIDAY...ESPECIALLY ACROSS SOUTH AND
EASTERN PR AS MOISTURE. THE USVI IS FORECAST TO HAVE ONLY A FEW
HUNDREDTHS OF AN INCH OF RAIN OVER THE NEXT COUPLE OF DAYS...BUT
MORE SIGNIFICANT RAINFALL IS EXPECTED THIS WEEKEND. THE 5-DAY
TOTAL RAINFALL FORECAST IS CURRENTLY SUGGESTING JUST OVER 2 INCHES
OF RAIN ACROSS EAST-SOUTHEAST PR AND ABOUT 1.5 INCHES ACROSS
NW-PR...WITH THE NORTHERN USVI OBSERVING ABOUT AN INCH OF RAIN AND
ST. CROIX UNDER A HALF AN INCH.
ALAMO...WPC (USA)
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