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FXCA20 KWBC 291216
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
816 AM EDT THU AUG 29 2024
WEEKLY DISCUSSION FOR PUERTO RICO AND THE USVI AUG 29/12UTC:
THE ANALYSIS OF THE MJO AND EQUATORIAL WAVES CONTINUES SHOWING A
STRONG UPPER CONVERGENT/DRY SIGNAL OVER THE CARIBBEAN DURING THE
NEXT SEVERAL DAYS. NEVERTHELESS...OBSERVATIONS AND MODEL DATA ARE
TRENDING TOWARDS INTENSIFYING A TROPICAL WAVE CURRENTLY
PROPAGATING ALONG 40W IN THE TROPICAL NORTH ATLANTIC. ALTHOUGH THE
BULK OF THE CONVECTION WITH THIS SYSTEM WILL LIKELY PASS TO THE
SOUTH OF PUERTO RICO SOMETIME AROUND WEDNESDAY NEXT WEEK.
THE CURRENT CONDITIONS SHOW A TRADE WIND SURGE DISSIPATING ACROSS
THE MONA PASSAGE AWAY FROM PUERTO RICO. THIS SYSTEM IS TRAILED BY
A DRIER AIR MASS CHARACTERIZED BY WEAKER PERTURBATIONS PROPAGATING
IN THE EASTERLY TRADES. PRECIPITABLE WATER IS FORECAST TO REMAIN
NEAR NORMAL THROUGH THE FORECAST CYCLE.
REGARDING THE WEEKLY FORECAST...EXPECT GENERALLY SEASONAL
CONDITIONS THROUGH EARLY NEXT WEEK...AS WEAK TRADE WIND
PERTURBATIONS ARE FORECAST TO MOVE IN FROM THE EAST ACCOMPANIED BY
NEAR NORMAL VALUES OF PRECIPITABLE WATER. THE TRADES ARE FORECAST
TO REMAIN PRIMARILY AS EASTERLIES UNTIL SUNDAY...WHEN EXPECT AN
EAST-SOUTHEASTERLY WIND DIRECTION TO DEVELOP. THIS WILL FAVOR
AFTERNOON CONVECTION IN THE WESTERN CORDILLERA THROUGH
SATURDAY...SHIFTING TO NORTHWEST PUERTO RICO BY SUNDAY ONWARD.
THE SYSTEM OF INTEREST IS THE TROPICAL DISTURBANCE LOCATED NEAR
40W. TWO FACTORS WE ARE MONITORING AT THE INTERNATIONAL DESKS ARE
(1) THE IMPACTS OF AN EXITING TROPOSPHERIC KELVIN WAVE AND (2) THE
CYCLOGENETIC IMPACTS OF THE BASE OF A TUTT LOCATED IN THE CENTRAL
ATLANTIC. FURTHERMORE...RESEARCH HAS DEMONSTRATED THAT ROTATION
CAN BE FAVORED ABOUT TWO DAYS AFTER A KELVIN WAVE EXITS A REGION
WHERE A TROPICAL WAVE IS PRESENT. CONSIDERING THESE FACTORS AND
MODEL TRENDS STARTING TO AGREE ON A ROBUST WAVE OR POTENTIALLY
CLOSED CIRCULATION IN THE EASTERN CARIBBEAN EARLY TO MID NEXT
WEEK...IT IS IMPORTANT TO CONTINUE MONITORING. NOTICE THAT CURRENT
MODELS ARE AGREEING ON A ROBUST FEEDER BAND-LIKE STRUCTURE
DEVELOPING WELL TO THE NORTHEAST OF THE CYCLONE. IF THIS
MATERIALIZES...A MOIST PLUME OF 55-60MM OF PRECIPITABLE WATER
MIGHT ARRIVE IN PUERTO RICO AND THE VI SOMETIME DURING WEDNESDAY
SEPTEMBER 4TH. THE CURRENT SOLUTIONS ARE SHOWING A POTENTIAL FOR
ECHO TRAINING...WHICH COULD EASILY YIELD TO 24-HR RAINFALL
ACCUMULATIONS EXCEEDING 4-6 INCHES IN EXTENSIVE REGIONS. AT THIS
TIME...MODELS ARE SUGGESTING POTENTIAL MAXIMA NEAR 8 INCHES DUE TO
OROGRAPHIC ENHANCEMENT IN EASTERN PUERTO RICO...BUT IT IS WAY TO
EARLY FOR CONFIDENCE. THE KEY MESSAGE IS THAT THIS SYSTEM NEEDS TO
BE CLOSELY MONITORED AS A POTENTIAL EXCESSIVE RAINFALL THREAT FOR
WEDNESDAY AND THURSDAY NEXT WEEK.
GALVEZ...WPC (USA)
LEDESMA...WPC (USA)
ACOSTA...WPC (USA)
TINOCO...WPC (USA)
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