205
FXCA20 KWBC 261525
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1024 AM EST THU DEC 26 2024
WEEKLY DISCUSSION FOR PUERTO RICO AND THE USVI DEC 26 1530 UTC:
OVER THE NEXT SEVERAL DAYS THE DIVERGENT PHASE OF THE
MADDEN-JULIAN OSCILLATION IS EXPECTED OVER MOST OF THE CARIBBEAN
BASIN...CONTINUING INTO THE NEXT WORK WEEK. BY THE WEEKEND AND
INTO THE NEXT WEEK AN ATMOSPHERIC KELVIN WAVE PROPAGATES INTO THE
BASIN AND EXTENDS INTO THE NORTH CARIBBEAN...SIGNALING THE
POTENTIAL FOR FAVORABLE UPPER DIVERGENCE FOR VENTILATION FOR
CONVECTION. TAKING A LOOK AT THE NORTH ATLANTIC OSCILLATION AND
ARCTIC OSCILLATION...THEY ARE BOTH REMAINING POSITIVE FOR THE NEXT
FEW DAYS...YET THE GUIDANCE FROM CPC IS SUGGESTING THE POTENTIAL
FOR BOTH TO BECOME NEGATIVE OVER THE WEEKEND AND INTO THE NEXT
WORK WEEK. THESE CAN ASSIST WITH THE POTENTIAL FOR COLDER AIR FROM
THE NORTH TO ENTER THE REGION AND FOR THE POTENTIAL FOR FRONTAL
BOUNDARIES TO ENTER THE CARIBBEAN BASIN FURTHER SOUTH WHEN THE
OSCILLATIONS ENTER THEIR NEGATIVE PHASES.
LOOKING INTO THE SYNOPTIC CONDITIONS OVER THE NEXT SEVERAL
DAYS...THE UPPER AND MID LEVELS OVER PUERTO RICO/VI WILL SEE THE
PRESENCE OF RIDGING AND AN UPPER JET TO THE NORTH WILL HELP
PROPAGATE SHORT WAVE TROUGHS OVER THE REGION WHILE AN MID TO UPPER
TROUGH INTERACTS WITH THE RIDGE ON THURSDAY AND FRIDAY. IN THE
LOWER LEVELS...A TROUGH IS PROPAGATING FROM EAST TO WEST OVER THE
ISLANDS AND BRINGING SOME AVAILABLE MOISTURE. PRECIPITABLE WATER
IS EXPECTED TO BE AROUND 1.6-1.9 INCHES ON THURSDAY AND
FRIDAY...WHILE WINDS IN THE LOWER LEVELS ARE EXPECTED TO BE
GENERALLY FROM THE EAST AND SHIFTING TO SLIGHTLY NORTH AS A
FRONTAL BOUNDARY NEARS THE ISLAND BY SATURDAY. SHOWERS COULD BE
EXPECTED IN THE EAST AND NORTH...WHERE TOTALS COULD BE IN THE
RANGE OF 15-25MM/DAY...WITH ISOLATED HIGHER AMOUNTS POSSIBLE.
OVER THE WEEKEND...A SHIFT TO DRIER CONDITIONS IS EXPECTED AS A
FRONTAL BOUNDARY PROPAGATES SOUTHWARD OVER PUERTO RICO/VI BY
SATURDAY EVENING. PRECIPITABLE WATER LEVELS COULD REACH BELOW 1.5
INCHES STARTING ON SATURDAY INTO SUNDAY. WITH THE DRIER CONDITIONS
AND A RIDGE ENTERING THE REGION FROM THE NORTH IN THE MID TO LOWER
LEVELS...A TRADE WIND INVERSION IS EXPECTED TO DEVELOP OVER PUERTO
RICO/VI AT AROUND 850-800 HPA LEVELS...INHIBITING THE DEVELOPMENT
FOR DEEP CONVECTION. THESE DRY CONDITIONS WILL CONTINUE INTO THE
REST OF THE WORK WEEK AS DRY AIR BEHIND THE FRONTAL BOUNDARY
CONTINUES MOVING SOUTHWARD OVER THE REGION. A BLOCKING PATTERN IN
THE MID TO LOWER LEVELS WILL KEEP MOST MOISTURE SOUTH AND WEST OF
THE ISLANDS INTO THE MIDDLE OF THE WEEK. ALTHOUGH THE POTENTIAL
FOR DEEP CONVECTION IS SUPPORTED BY THE MJO AND KELVIN WAVE
PROPAGATION OVER THE REGION...THE LACK OF AVAILABLE MOISTURE WILL
NOT FAVOR HEAVY PRECIPITATION OVER THE NEXT SEVERAL
DAYS...ESPECIALLY INTO THE FOLLOWING WORK WEEK. ANY PRECIPITATION
EXPECTED COULD BE SEEN ALONG THE NORTH AND EASTERN PORTIONS
ISLANDS WHERE TOTALS ARE EXPECTED TO REMAIN ISOLATED AND
LOCALIZED.
CASTELLANOS...WPC(USA)
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page