521
FXCA20 KWBC 121250
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
749 AM EST TUE DEC 12 2023
PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI DEC 12/12UTC:
A NE-ENE WIND PATTERN IS EXPECTED OVER THE NEXT SEVERAL DAYS
ACROSS THE NORTHEAST CARIBBEAN. A STRONG SURFACE HIGH PRESSURE
ACROSS THE NORTH CENTRAL ATLANTIC WILL GRADUALLY MOVE EAST INTO
THE NORTHEAST ATLANTIC BY THURSDAY. A SURFACE LOW PRESSURE WILL
START MOVING NORTH INTO THE CENTRAL ATLANTIC ON WEDNESDAY INTO
THURSDAY...AS ANOTHER BROAD SFC HIGH PRESSURE MOVES INTO THE
WESTERN ATLANTIC FROM FRIDAY INTO THE WEEKEND. THAT SAID...A SFC
LOW PRESSURE MAY MOVE FROM THE GULF OF MEXICO INTO THE
SOUTHWESTERN ATLANTIC ON SATURDAY INTO SUNDAY...CAUSING A CHANGE
IN WIND DIRECTION TO AN E-ESE DIRECTION OVER THE CARIBBEAN. THE
MID LEVELS WILL BE DOMINATED BY A WEAK RIDGE WITH LIGHT WINDS FOR
THE REST OF THE WEEK. THE UPPER LEVELS WILL ALSO HAVE A RIDGE OVER
THE LOCAL ISLANDS BUT AN UPPER TROUGH IS FORECAST TO MOVE IN ON
LATE THURSDAY INTO FRIDAY...THOUGH FLATTENING BY SATURDAY.
HOWEVER...THERE MAY BE SOME DIVERGENCE IN THE UPPER LEVELS THIS
WEEKEND AS THE WINDS WILL BE STRONGER OVER AND TO THE EAST OF THE
LOCAL ISLANDS.
THE AVAILABLE MOISTURE WILL BE BELOW NORMAL TODAY AND
WEDNESDAY...BUT WILL START TO INCREASE ON THURSDAY...REMAINING
ABOVE NORMAL FROM LATE THURSDAY INTO THE WEEKEND. THE TWIN
ALGORITHM IS SUGGESTING THAT THERE WILL BE AN INVERSION NEAR THE
800-850MB LEVEL THROUGH THURSDAY...WITH THE INVERSION ERODING ON
FRIDAY ONWARD. THE EGDI ALGORITHM IS SUGGESTING THAT THERE MAY BE
A CHANCE OF THUNDERSTORMS THIS WEEKEND AS WELL. THIS COULD BE IN
RESPONSE TO THE INCREASE IN MOISTURE EXPECTED...AS THE SFC LOW
MOVES FROM THE GULF TO THE SW ATLANTIC...THE QUICK UPPER TROUGH
OVER THE CARIBBEAN...AND THE DIVERGENCE ALOFT THAT IS EXPECTED.
THE RAINFALL FORECAST FAVORS NORTH AND EASTERN PR...AS WELL AS THE
USVI...TO RECEIVE SOME RAIN EACH DAY...BUT GENERALLY IN BRIEF
SHOWERS. HOWEVER AS MOISTURE INCREASES LATE THIS WEEK AND INTO THE
WEEKEND...THE AMOUNTS OF RAIN ARE FORECAST TO INCREASE ACROSS THE
AREA. FOR TODAY AND WEDNESDAY...THE RAINFALL MAX IS FORECAST TO BE
AT AROUND A HALF AN INCH OF RAIN OR LESS...BUT OVER A HALF AN INCH
TO AROUND 0.75 INCHES ARE FORECAST FROM THURSDAY ONWARD ACROSS
NORTH AND EASTERN PR. THERE IS A CHANCE OF SIGNIFICANT SHOWERS
ACROSS WESTERN PR ON FRIDAY AFTERNOON AS SOME SEA BREEZE
CONVERGENCE MAY COMBINE WITH THE WEAK UPPER TROUGH AND THE
MOISTURE ADVECTION EXPECTED. THE 5-DAY TOTAL RAINFALL IN THE
FORECAST SUGGESTS OVER 2 INCHES OF RAIN ACROSS EASTERN AND
NORTHEASTERN PR...NEAR ONE INCH ACROSS WESTERN PR...AND BETWEEN
0.50 AND 0.75 INCHES FOR THE USVI.
ALAMO...WPC (USA)
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