051
FXCA20 KWBC 291300
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
859 AM EDT WED MAR 29 2023
PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI FROM MAR
29/12UTC: THE AVAILABLE MOISTURE WILL INCREASE TODAY TO NEAR
NORMAL LEVELS AS FRAGMENTS OF MOISTURE MOVE THROUGH TODAY AND
THURSDAY...WITH MOISTURE DECREASING AGAIN ON FRIDAY AND INTO THE
WEEKEND. SCATTERED SHOWERS HAVE BEEN AFFECTING EASTERN PR IN THE
MORNING AND THESE SHOWERS WILL CONTINUE INTO THE MID MORNING
HOURS. THIS AFTERNOON...SHOWERS ARE FORECAST TO DEVELOP ACROSS
WESTERN PR AS THE INCREASE IN MOISTURE COMBINES WITH THE LOCAL
EFFECTS. THE TOTAL RAINFALL AMOUNTS ARE EXPECTED TO BE BETWEEN A
QUARTER OF AN INCH TO A HALF AN INCH ACROSS AREAS OF EASTERN PR
DUE TO THE MORNING SHOWERS...THEN SIMILAR AMOUNTS ACROSS WESTERN
PR DUE TO THE LOCALLY INDUCED SHOWERS. THAT SAID...SMALL AREAS
WITH HIGHER AMOUNTS OF RAIN WILL NOT BE RULED OUT AS A
POSSIBILITY. THURSDAY LOOKS VERY SIMILAR TO TODAY...AND THE
FORECAST REFLECTS THAT.
BY FRIDAY ONWARD...THE AVAILABLE MOISTURE WILL DECREASE...AND THE
SHOWER ACTIVITY AND FORECAST WILL BE LESS ON FRIDAY AND SATURDAY.
HOWEVER...THERE WILL BE A NARROW BAND OF MOISTURE IN THE AREA JUST
AHEAD OF A COLD FRONT...AND THE MODEL GUIDANCE IS STILL DIFFERING
IN TIMING AND LOCATION FROM RUN TO RUN AS WELL AS AMONG THE MODELS
THEMSELVES. AT THIS TIME THERE IS A POSSIBILITY OF A PREFRONTAL
TROUGH OVER THE AREA LATE THIS WEEKEND...WHICH WILL CAUSE GOOD
CLOUD COVER AND POSSIBLY PERSISTENT SHOWER ACTIVITY ACROSS THE
NORTHEASTERN CARIBBEAN...BUT AGAIN...THERE IS SOME UNCERTAINTY ON
THE PRECISE LOCATION OF THIS NARROW BAND OF MOISTURE AND RAIN
ACROSS THE AREA.
AT THE SURFACE THERE IS A HIGH PRESSURE ACROSS THE EASTERN
ATLANTIC...KEEPING EASTERLY WINDS LOCALLY...BUT LIGHTER AS A
SURFACE LOW PRESSURE MOVES EAST ACROSS THE WESTERN
ATLANTIC...RELAXING THE LOCAL PRESSURE GRADIENT. LATE
THURSDAY...ANOTHER SURFACE HIGH PRESSURE STARTS TO MOVE IN THE THE
WESTERN ATLANTIC ONCE AGAIN...WHICH WILL MOVE EAST AND SHOULD BE
IN THE CENTRAL ATLANTIC BY SUNDAY. ACROSS THE MID LEVELS THERE IS
A HIGH PRESSURE ACROSS THE EASTERN ATLANTIC..WHILE A MID LEVEL LOW
IS PRESENT ACROSS THE WESTERN ATLANTIC...PERSISTING THROUGH
THURSDAY. THEN...ANOTHER MID LEVEL HIGH PRESSURE WILL MOVE IN LATE
FRIDAY. THERE IS NO STRONG TRADE WIND CAP EXPECTED TODAY AND IT IS
EXPECTED TO WEAKEN EVEN MORE ON THURSDAY INTO FRIDAY...BUT THE
TRADE WIND INVERSION WILL RETURN LATE FRIDAY INTO THE WEEKEND.
ACROSS THE UPPER LEVELS...A WEAK UPPER TROUGH WEST OF THE LOCAL
ISLANDS IS FORECAST TO DEVELOP LATE THURSDAY INTO FRIDAY. THE
UPPER TROUGH WILL BE MOVING IN FROM THE WEST WITH ITS AXIS MOVING
THROUGH PR/USVI ON FRIDAY INTO SATURDAY. HOWEVER...THE MODEL
SOLUTIONS STILL DO NOT DO MUCH IN TERMS OF RAINFALL OR CONVECTION
BEING ENHANCED BY THIS UPPER TROUGH...PROBABLY SINCE THERE WILL BE
A MID LEVEL HIGH PRESSURE AND TRADE WIND INVERSION EXPECTED.
ALAMO...WPC (USA)
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