771
FXCA20 KWBC 071237
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
836 AM EDT FRI APR 07 2023
PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI FROM APR
07/12UTC: OUT OF THE NEXT 5 DAYS...TODAY IS EXPECTED TO BE THE
MOST ACTIVE. HOWEVER...THE INSTABILITY WILL DECREASE GRADUALLY
WITH EACH PASSING DAY. THE PRECIPITABLE WATER WILL STAY NEAR OR
SLIGHTLY ABOVE NORMAL OVER THE NEXT 5 DAYS...BUT THE REST OF THE
PARAMETERS WILL TREND TOWARDS STABILITY. SHOWERS AND THUNDERSTORMS
ARE FORECAST TODAY ESPECIALLY ACROSS EASTERN AND NORTHWESTERN PR
AS WELL AS THE USVI. THE ECMWF MODEL GUIDANCE IS STILL THE MOST
AGGRESSIVE IN TERMS OF TOTAL RAINFALL...SUGGESTING OVER 2 INCHES
ACROSS SOME AREAS TODAY...BUT OUR FORECAST IS A BIT MORE
CONSERVATIVE WITH THE RAINFALL AMOUNTS AROUND 0.75 AND 1.25 INCHES
ACROSS PORTIONS OF EASTERN AND NORTHWESTERN PR...AND BETWEEN 0.50
AND 0.75 FOR THE USVI.
AT THE SURFACE THERE IS A HIGH PRESSURE ACROSS THE CENTRAL
ATLANTIC CAUSING EASTERLY WINDS...BUT A SURFACE LOW WILL ENTER THE
WESTERN ATLANTIC BY SATURDAY...WHICH WILL CAUSE WINDS TO SHIFT TO
THE SOUTHEAST...BECOMING SOUTHERLY BY SUNDAY...RETURNING TO AN
EASTERLY DIRECTION LATE TUESDAY. IN THE MID LEVELS...THERE IS A
LOW PRESSURE CENTERED OVER HISPANIOLA...WHICH IS WEAKENING AND IS
EXPECTED TO FLATTEN BY SUNDAY...THEN A MID LEVEL TROUGH WILL
DEVELOP ACROSS THE WESTERN ATLANTIC ON MONDAY...BUT IT IS EXPECTED
TO BE FAR ENOUGH NORTH TO NOT CAUSE TOO MUCH OF AN IMPACT ACROSS
THE LOCAL ISLANDS. IN THE UPPER LEVELS...THE TUTT REMAINS FAIRLY
STRONG JUST NORTH-NORTHWEST OF THE LOCAL ISLANDS...CAUSING STRONG
WINDS AND DIVERGENCE OVER THE LESSER ANTILLES. THE TUTT IS ALSO
EXPECTED TO WEAKEN ON SATURDAY AND FLATTEN BY SUNDAY...WITH A WEAK
UPPER RIDGE DEVELOPING OVER THE CARIBBEAN BY TUESDAY. THE 500MB
TEMPERATURES ARE STILL COLD...AT AROUND -11C THOUGH EXPECTED TO
GRADUALLY INCREASE WITH EACH PASSING DAY...POSSIBLY REACHING -7
SUNDAY EVENING...EVEN WARMER IN THE UPCOMING WORKWEEK. THE
700-500MB RELATIVE HUMIDITY IS STILL ABOVE NORMAL...BUT EXPECTED
TO BE WITHIN THE NORMAL RANGE BY SUNDAY. THE LATEST ENHANCED
GALVEZ-DAVISON INDEX (EGDI) SUGGESTS THE POSSIBILITY OF ISOLATED
THUNDERSTORMS TODAY. THE INDEX DECREASES FOR SATURDAY AND EVEN
WEAKER INTO THE UPCOMING WORKWEEK.
IN TERMS OF FORECAST AMOUNTS...FOR TODAY...AMOUNTS NEAR ONE INCH
OF RAIN...GIVE OR TAKE ABOUT A QUARTER OF AN INCH...OVER EASTERN
AND NORTHWEST PR. THE USVI IS FORECAST TO OBSERVE AROUND A HALF AN
INCH TO A MAXIMA OF THREE QUARTERS OF AN INCH OF RAIN. THE
DECREASING THUNDERSTORM TREND EXPECTED WILL RESULT IN LOWER
RAINFALL AMOUNTS EACH PASSING DAY...WITH RAINFALL MAXIMA OF AN
INCH OR LESS BY SATURDAY...AROUND 0.75 INCHES OR LESS ON
SUNDAY...AND EVEN UNDER A HALF AN INCH FOR MONDAY AND TUESDAY.
ALAMO/ACOSTA...WPC (USA)
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