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FXCA20 KWBC 091232

PMDCA 



TROPICAL DISCUSSION - INTERNATIONAL DESKS

NWS WEATHER PREDICTION CENTER COLLEGE PARK MD

832 AM EDT THU MAY 09 2024



WEEKLY DISCUSSION FOR PUERTO RICO AND THE USVI MAY 09/12UTC:



SYNOPSIS: SATELLITE IMAGERY AND MODELS SHOW THAT AN EXTENSIVE

MID-UPPER TROUGH CONTINUES EXTENDING FROM BERMUDA INTO THE

NORTHEAST CARIBBEAN. SHORT WAVE VORTICES ARE PROPAGATING EASTWARD

ALONG THE BASE OF THE MAIN TROUGH. THE EASTERNMOST SHORT WAVE

TROUGH EXTENDS ALONG 58-60W. AS THE TROUGH EXITS THE DRIER AIR

MASS TO THE WEST IS SUSTAINING DRYING TREND OF THE MID AND UPPER

TROPOSPHERE OVER THE LOCAL ISLANDS. THAT BEING SAID...PRECIPITABLE

WATER VALUES REMAIN CLOSE TO 50MM OR ABOVE NORMAL FOR THIS TIME OF

THE YEAR. THIS IS IN ASSOCIATION WITH A ZONALLY ORIENTED MOIST

PLUME PRODUCED BY A PERSISTENT STATIONARY FRONT THAT HAS LOST

BAROCLINICITY IN THE LAST TWO DAYS. INCREASINGLY UPPER CONVERGENT

CONDITIONS ARE ALSO PLAYING A ROLE IN LIMITING VERTICAL

DEVELOPMENT...THUS EXPECT A NOTICEABLE DECREASE IN THE COVERAGE

AND INTENSITY OF DIURNAL CONVECTION TODAY WITH RESPECT TO EARLIER

THIS WEEK.



FORECAST: AFTER SEVERAL DAYS UNDER THE INFLUENCE OF THE MOIST

PLUME AND PROPAGATING SHORT WAVE MID-UPPER TROUGHS IN THE

WESTERLIES...THE MID-UPPER TROPOSPHERIC PATTERN IS FORECAST TO

GRADUALLY EVOLVE INTO A DRIER ONE. MODELS AGREE ON THE MID-LEVEL

RIDGE CURRENTLY LOCATED OVER MEXICO/GULF OF MEXICO/WESTERN

CARIBBEAN CONTINUING TO BUILD EASTWARD INTO THE CENTRAL AND

EASTERN CARIBBEAN...SETTING FOOTHOLD OVER PUERTO RICO BETWEEN

SUNDAY AND MONDAY...TO PERSIST INTO AT LEAST MID-WEEK. THIS IS

CONSISTENT WITH AN EXPECTED STRENGTHENING OF THE TRADE WIND CAP

EARLY NEXT WEEK...RESULTING IN A NOTICEABLE DECREASE IN VERTICAL

DEVELOPMENT AND COVERAGE OF DEEP CONVECTION STARTING ON SUNDAY.

AVAILABLE MOISTURE IS FORECAST TO DECREASE...BUT TO REMAIN WITHIN

CLIMATOLOGICAL NORMALS. HOWEVER...LESS FAVORABLE DYNAMICS FOR

ASCENT WILL YIELD TO MORE CONSERVATIVE RAINFALL ACCUMULATION

STARTING SUNDAY.



IN THE MEAN TIME...THE MID-UPPER TROUGH PATTERN IS FORECAST TO

PERSIST THROUGH SATURDAY. LIMITED AVAILABLE MOISTURE AND LIMITED

SATURATION/CLOUD COVER IN THE MID AND UPPER TROPOSPHERE WILL

ACTUALLY STIMULATE DIURNAL HEATING...FAVORING HIGH RAINFALL RATES

IN AFTERNOON THUNDERSTORMS THAT DEVELOP ESPECIALLY ON THURSDAY AND

FRIDAY. UNDER THE INFLUENCE OF WEAK SOUTHEASTERLY TRADES ON

THURSDAY AND FRIDAY...EXPECT STRONG DIURNAL BREEZE CONVERGENCE TO

FOCUS IN INTERIOR PORTIONS OF NORTHERN AND NORTHWEST PUERTO RICO

WHERE AFTERNOON CONVECTION IS EXPECTED. EXPECT DIURNAL MAXIMA IN

THE 1-2 INCH RANGE...ALTHOUGH ISOLATED MAXIMA NEAR 3 INCHES CANNOT

BE RULED OUT.



GALVEZ...WPC (USA)





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