Prognostic Meteorological Discussion
Issued by NWS
Issued by NWS
061 FXCA20 KWBC 021905 PMDCA TROPICAL DISCUSSION - INTERNATIONAL DESKS NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 304 PM EDT THU MAY 02 2024 WEEKLY DISCUSSION FOR PUERTO RICO AND THE USVI MAY 02/12UTC: A WET PATTERN IS EXPECTED OVER PR/USVI OVER THE NEXT SEVERAL DAYS. THERE IS A GOOD CHANCE OF THUNDERSTORMS LATE THIS WEEK INTO THE WEEKEND...WITH SOME OF THE THUNDERSTORMS WITH THE POTENTIAL OF BEING STRONG. THE OVERALL MOISTURE WILL BE FROM NORMAL TO ABOVE NORMAL FOR THE NEXT SEVERAL DAYS...WITH THE LATEST GUIDANCE SUGGESTING PRECIPITABLE WATER VALUES BETWEEN 1.9 TO 2.3 INCHES THROUGH THE NEXT 5 TO 7 DAYS...AND PRECIPITABLE WATER AT 2 INCHES OR HIGHER STARTING ON FRIDAY EVENING. THE LOW TO MID LEVEL RELATIVE HUMIDITY IS ALSO FORECAST TO BE ABOVE NORMAL FROM FRIDAY ONWARD. A MID TO UPPER LEVEL TROUGH IS APPROACHING FROM THE WEST...AND THE 500MB HEIGHT ANOMALY IS VERY PRONOUNCED OVER HISPANIOLA INTO THE CENTRAL CARIBBEAN...WHILE IT CAUSES THE 500 MB TEMPERATURES TO BE NEAR -7C TO -8C ON FRIDAY AND SATURDAY OVER THE LOCAL ISLANDS. OVER THE NEXT FEW DAYS...THE MID LEVEL TROUGH AXIS WILL REMAIN OVER THE CENTRAL CARIBBEAN...WHILE THE MID AND UPPER LEVEL WINDS STRENGTHEN OVER THE NORTHEAST CARIBBEAN...CAUSING STRONG DIVERGENCE ALOFT FROM FRIDAY INTO THE WEEKEND. THE DIVERGENCE ALOFT...COMBINED WITH THE COLDER MID LEVEL TEMPS...AND THE INCREASE IN MOISTURE AT ALL LEVELS...WILL CAUSE AN ENHANCED CHANCE OF THUNDERSTORMS FROM FRIDAY INTO THE WEEKEND. THE EGDI ALGORITHM DOES SUGGEST THE POTENTIAL FOR SCATTERED THUNDERSTORMS...ESPECIALLY FOR FRIDAY AFTERNOON INTO SATURDAY...THOUGH IT CONTINUES TO SUGGEST POSSIBLE ISOLATED TO SCATTERED THUNDERSTORMS INTO NEXT WEEK AS WELL. THAT SAID...THE GR02T ALGORITHM SUGGESTS A MARGINAL RISK FOR SEVERE THUNDERSTORMS FROM FRIDAY INTO THIS WEEKEND. THIS IS POSSIBLY DUE TO THE POSITIONING OF THE MID LEVEL TROUGH AND THE COLD MID LEVEL TEMPS...HOWEVER...THE MODEL GUIDANCE DOES NOT TAKE THE -8C MID LEVEL TEMP CONTOUR OVER PR...KEEPING IT TO THE NORTH OF THE LOCAL ISLANDS...AND THEREFORE NOT SUGGESTING A HIGHER CHANCE OF SEVERE THUNDERSTORMS AND HAIL POTENTIAL...THOUGH ISOLATED STRONG STORMS WITH SMALL HAIL WOULD NOT BE RULED OUT AT THIS POINT. THE GR02T ALGORITHM DOES NOT SUGGEST POTENTIAL FOR STRONG THUNDERSTORMS AFTER THIS WEEKEND. AS MENTIONED ABOVE...THE HIGHER THAN NORMAL MOISTURE IS EXPECTED TO CONTINUE INTO NEXT WEEK. THE GLOBAL AND LONG RANGE MODELS ARE SUGGESTING A PERSISTENT AND RELATIVELY NARROW LINE OF MOISTURE OVER THE NORTHEAST CARIBBEAN...ASSOCIATED WITH A FRONTAL BOUNDARY EXTENDING FROM THE CENTRAL ATLANTIC. A SFC HIGH PRESSURE OVER THE WEST TROPICAL ATLANTIC WILL ALSO HELP KEEP THE MOISTURE OVER THE LEEWARD ISLANDS TO THE WEST INTO HISPANIOLA. THERE IS SOME DISCREPANCIES IN THE WIND FLOW OVER THE NORTHEAST CARIBBEAN AMONG THE MODEL GUIDANCE IN THE EXTENDED FORECAST...THAT IS FOR NEXT TUESDAY INTO WEDNESDAY. THE OVERALL WIND FLOW COULD DICTATE WHERE THE HIGHEST RAINFALL AMOUNTS COULD BE EARLY INTO THE MIDDLE OF NEXT...BUT BEING THIS FAR INTO THE FORECAST PERIOD...THERE IS CONSIDERABLE UNCERTAINTY. THAT BEING SAID...BOTH GLOBAL MODELS ARE IN AGREEMENT THAT HIGH MOISTURE CONTENT WILL BE PRESENT OVER THE AREA INTO THE MIDDLE OF NEXT WEEK...SO SOME SIGNIFICANT SHOWER ACTIVITY COULD STILL BE EXPECTED WITH THE DEEP MOISTURE THAT IS FORECAST. THE IMPACT OF THE RAINFALL EARLY NEXT WEEK COULD BE SIGNIFICANT...THOUGH STRONG THUNDERSTORMS ARE NOT EXPECTED EARLY NEXT WEEK...THE SOILS ACROSS SOME AREAS OF PR/USVI COULD BE SATURATED BY THEN...CONSIDERING WHAT IS EXPECTED THIS WEEKEND. ALAMO...WPC (USA) $$