581
FXCA20 KWBC 071247
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
846 AM EDT MON AUG 07 2023
PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI FROM AUG
07/12UTC: AN ACTIVE WEEK IS FORECAST WITH NEAR TO ABOVE NORMAL
MOISTURE PERSISTING THROUGH MOST OF THE WORKWEEK. PRECIPITABLE
WATER WILL RANGE GENERALLY BETWEEN 2 AND 2.4 INCHES. THETA-E WILL
ALSO REMAIN ABOVE NORMAL THIS WEEK. THERE ARE A COUPLE OF TROPICAL
WAVES MOVING IN...ONE FROM TUESDAY INTO WEDNESDAY...AND ANOTHER
FROM THURSDAY INTO FRIDAY. THE LATTER TROPICAL WAVE APPREARS TO
HAVE MOST OF THE DEEP MOISTURE TO THE SOUTH OF THE LOCAL
ISLANDS...BUT STRONG WINDS...UPWARDS OF 25 KNOTS ARE FORECAST BY
THE GFS MODEL. IN ADDITION...THERE IS A TUTT ASSOCIATED WITH THIS
TROPICAL WAVE...AND ONLY A SLIGHT ADJUSTMENT NORTHWARD OF THE
MOISTURE AND INSTABILITY COULD CAUSE SIGNIFICANT THUNDERSTORM
ACTIVITY OVER PR/USVI.
AN AREA OF DISTURBED WEATHER NORTH OF PR IS PROVIDING SOME
MOISTURE TO THE LOCAL AREA. THERE IS ALSO SOME INSTABILITY IN THE
UPPER LEVELS WITH A TUTT TO THE NORTH OF THE LOCAL ISLANDS.
THEREFORE SOME SHOWER ACTIVITY IS EXPECTED FOR EASTERN PR AND THE
USVI IN THE MORNING AND THEN AFTERNOON CONVECTION ACROSS WESTERN
PR AND PORTIONS OF THE SAN JUAN METRO. AS THE TROPICAL WAVE
APPROACHES ON TUESDAY...THERE WILL BE A BRIEF DECREASE IN
MOISTURE...BUT WILL QUICKLY INCREASE BY THE AFTERNOON HOURS AND
PERSISTING ABOVE NORMAL INTO WEDNESDAY. THE RAINFALL PATTERN WILL
BE RELATIVELY TYPICAL...WITH SHOWERS AND ISOLATED THUNDERSTORMS
AFFECTING EASTERN PR AND THE USVI AS WELL AS AFTERNOON
THUNDERSTORMS AFFECTING WESTERN TO NORTHWESTERN PR ON TUESDAY AND
WEDNESDAY. UNCERTAINTY STARTS TO INCREASE ON THURSDAY INTO
WEDNESDAY WITH THE TROPICAL WAVE THAT WOULD BE EXPECTED. THE MODEL
GUIDANCE IS SUGGESTING DEEP MOISTURE AND A SIGNIFICANT VORTICITY
INCREASE FOR THE LATTER PART OF THE WORKWEEK...BUT MOST OF IT
APPEARS TO REMAIN SOUTH OF THE ISLANDS...BUT JUST BARELY. THAT
BEING SAID...A TUTT NORTH OF THE ISLANDS IS ALSO FORECAST...AND IT
IS NOT UNCOMMON FOR THESE TUTTS TO PULL MOISTURE NORTHWARD
COMPARED TO WHAT THE MODELS SUGGEST. THEREFORE...CONFIDENCE IS
LOWER THAN NORMAL FOR THE FORECAST ON DAYS 4 AND 5...AS A SMALL
SHIFT NORTH COULD MEAN MUCH DEEPER MOISTURE AND INSTABILITY FOR
PR/USVI.
THE 5-DAY TOTAL RAINFALL FORECAST IS FOR PORTIONS OF W/NW PR TO
RECEIVE OVER 5 INCHES OF RAIN...WHILE EASTERN AND NORTHEASTERN PR
IS FORECAST TO OBSERVE AROUND 2.5 INCHES. THE USVI IS FORECAST TO
HAVE AROUND 0.75 TO 1 INCH OF RAIN OVER THE 5-DAY PERIOD.
ALAMO...WPC (USA)
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