496
FXCA20 KWBC 051523
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1022 AM EST THU DEC 05 2024
WEEKLY DISCUSSION FOR PUERTO RICO AND THE USVI DEC 05/14UTC:
MODEL GUIDANCE OF LARGE SCALE OSCILLATIONS SHOWS A WEAK UPPER
CONVERGENT MJO OVER THE CARIBBEAN FOR AT LEAST THE NEXT WEEK. AT
THE SYNOPTIC SCALE...A STRONG LOW PRESSURE OVER THE NORTH CENTRAL
ATLANTIC HAS A COLD FRONT THAT IS EXTENDING TO THE
SOUTHWEST...REACHING 20N JUST NORTH OF PUERTO RICO AND HISPANIOLA
AS A WEAK STATIONARY FRONT. IN THE MID LEVELS...THERE IS A BROAD
HIGH PRESSURE ACROSS THE CARIBBEAN OVER THE NEXT SEVERAL
DAYS...THEN A MID LEVEL LOW AND AN ASSOCIATED TROUGH IS FORECAST
TO DEVELOP TO THE NORTHEAST OF THE LEEWARDS EARLY NEXT WEEK.
HOWEVER...PR/USVI IS EXPECTED TO REMAIN IN THE SUBSIDENT SIDE OF
THE MID LEVEL TROUGH. THE UPPER LEVELS WILL HAVE A SIMILAR
PATTERN...THERE WILL BE A BROAD HIGH PRESSURE OVER THE CARIBBEAN
THROUGH THE WEEKEND...THEN AN UPPER TROUGH WILL START DEVELOPING
EARLY NEXT WEEK TO THE NORTHEAST OF THE LEEWARD ISLANDS...BUT ONCE
AGAIN THE LOCAL ISLANDS WILL REMAIN IN THE SUBSIDENT SIDE...WITH
MAINLY NORTHERLY WINDS OVER THE NORTHEAST CARIBBEAN EARLY NEXT
WEEK.
IN TERMS OF MOISTURE...THE AVAILABLE MOISTURE WILL BE NEAR NORMAL
TODAY. MOISTURE WILL DECREASE SIGNIFICANTLY FRIDAY INTO
SATURDAY...WITH PRECIPITABLE WATER BEING BELOW NORMAL AT AROUND
1.0 TO 1.2 INCHES...BUT THEN INCREASING TO SLIGHTLY ABOVE NORMAL
DURING THE WEEKEND INTO EARLY NEXT WEEK...WITH PRECIPITABLE WATER
BETWEEN 1.6 AND 1.9 INCHES...THE PEAK BEING ON SATURDAY EVENING.
THE LOW TO MID LEVEL RELATIVE HUMIDITY VALUES WILL ALSO DECREASE
SIGNIFICANTLY FRIDAY INTO SATURDAY...THEN INCREASE SHARPLY
SATURDAY INTO SUNDAY AND REMAINING SLIGHTLY ABOVE NORMAL INTO NEXT
WEEK. THE RAINFALL AMOUNTS IN THE DAILY WEATHER FORECAST WOULD
CORRELATE WITH THE AMOUNT OF AVAILABLE MOISTURE.
IN TERMS OF THE RAINFALL PATTERN OVER PR/USVI...UNDER A PREVAILING
EAST TO NORTHEAST WINDS...THE NORTH AND EAST SECTIONS OF PR AND
THE USVI WOULD HAVE DAILY ISOLATED TO SCATTERED SHOWERS. AFTERNOON
CONVECTION OVER WESTERN PR DUE TO DIURNAL HEATING AND THE SEA
BREEZE CONVERGENCE IS EXPECTED TODAY...AND THEN AGAIN LATE IN THE
WEEKEND INTO EARLY NEXT WEEK. THE EGDI FORECAST ALGORITHM DOES
SHOW THE POSSIBILITY OF SHALLOW CONVECTION TO VERY ISOLATED
THUNDERSTORMS VERY LATE SATURDAY INTO SUNDAY. LITTLE TO NO RAIN IS
EXPECTED ACROSS WESTERN PR ON FRIDAY AND SATURDAY GIVEN THE DRY
AIR THAT WILL BE PRESENT OVER THE AREA. OVER THE NEXT 5 DAYS...THE
NORTHEAST PORTION OF PUERTO RICO IS FORECAST TO OBSERVE NEAR 2
INCHES OF RAIN...WITH AROUND 1-2 INCHES OF RAIN POSSIBLE ACROSS
THE WESTERN PORTIONS OVER THE NEXT 5 DAYS. OTHER AREAS OF PUERTO
RICO ARE FORECAST UNDER AN INCH OF RAIN...THOUGH VIEQUES AND
CULEBRA COULD OBSERVE AROUND 1.5 INCHES OR SO. THE USVI ARE
FORECAST BETWEEN 0.5 AND 1.5 INCHES OF RAIN.
ALAMO...WPC (USA)
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