539
FXCA20 KWBC 211756
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1255 PM EST FRI NOV 21 2025
FORECAST BULLETIN 21 NOVEMBER 2025 AT 1800 UTC:
THE BAHAMAS AND CARIBBEAN:
A LARGE AREA OF HIGH PRESSURE IS EXPECTED TO BRING STABLE
CONDITIONS AND LIMIT PRECIPITATION ACROSS THE BAHAMAS AND
CARIBBEAN. LIGHT PRECIPITATION IS LIKELY OVER EASTERN CUBA,
JAMAICA, AND HISPANIOLA FROM TODAY THROUGH SATURDAY WITH A PLUME
OF MOISTURE, A LOW-LEVEL TROUGH ENHANCING LOW-LEVEL MOISTURE
CONVERGENCE. LESS PRECIPITATION IS EXPECTED FROM SATURDAY
AFTERNOON THROUGH MONDAY MORNING AS DRY AIR IS ADVECTED INTO THE
REGION. LIMITED PRECIPITATION IS EXPECTED OVER THE FORECAST PERIOD
FOR PUERTO RICO AND THE LEEWARD ISLANDS AS A LOW-LEVEL
NORTHEASTERLY FLOW BRINGS DRY AIR INTO THE REGION.
THE WINDWARD ISLANDS, AND TRINIDAD AND TOBAGO CAN EXPECT SHOWERS
EACH DAY OF THE FORECAST PERIOD AS EASTERLY LOW-LEVEL FLOW BRINGS
MOISTURE. TOTALS WILL INCREASE TOWARDS THE END OF THE FORECAST
PERIOD, PARTICULARLY FOR TRINIDAD AND TOBAGO AND THE NORTHEASTERN
COAST OF VENEZUELA, AS A PLUME OF MOISTURE MOVES INTO THE AREA
GRADUALLY INCREASING THE PRECIPITABLE WATER AVAILABILITY REACHING
VALUES OVER 50MM ON SUNDAY.
SHOWERS DUE TO LOCAL EFFECTS AND DIURNAL HEATING CAN ALSO BE
EXPECTED ACROSS THE REGION DURING THE FORECAST PERIOD, BUT OVERALL
HIGH RAINFALL ACCUMULATIONS ARE NOT EXPECTED DUE TO LIMITED DEEP
MOISTURE AND THE SYNOPTIC PATTERN FAVORING A MORE STABLE
ENVIRONMENT.
MEXICO AND CENTRAL AMERICA:
AN UPPER-LEVEL TROUGH, REFLECTED AT MID- AND LOWER-LEVELS, OVER
SOUTHWESTERN U.S. IS EXPECTED TO REACH BAJA CALIFORNIA AND SONORA
TODAY AND CONTINUE TO AFFECT THE AREA THROUGH SUNDAY MORNING. AT
LOWER-LEVELS A COLD FRONT IS ALSO FORECASTED TO REACH BAJA
CALIFORNIA TODAY, AND START TO DISSIPATE OVER THE REGION ON
SUNDAY. THIS IS EXPECTED TO BRING HEAVY PRECIPITATION IN THE AREA
OVER THE NEXT TWO DAYS. THE HEAVIEST PRECIPITATION FOR BAJA
CALIFORNIA IS EXPECTED TO START ON FRIDAY EVENING THROUGH SATURDAY
AFTERNOON. TOTAL PRECIPITATION REACHING 50MM IS FORECASTED FROM
FRIDAY THROUGH SATURDAY MORNING. ADDITIONAL 30-60MM OF RAINFALL
ARE FORECASTED FROM SATURDAY THROUGH SUNDAY MORNING. FOR SONORA,
THE HIGHEST RAINFALL TOTALS ARE PROJECTED TO BE AROUND 20-35MM
FROM SATURDAY THROUGH SUNDAY.
A LOW-LEVEL TROUGH WILL BRING SOME LIGHT RAINFALL OVER BELIZE
TODAY, BUT A MID-LEVEL HIGH OVER THE CAMPECHE BAY AND AN UPPER
LEVEL-RIDGE OVER THE PACIFIC COAST OF CENTRAL AMERICA WILL LIKELY
LIMIT THE DEVELOPMENT OF STRONG THUNDERSTORMS AND CONVECTIVE
ACTIVITY. PRECIPITATION, HOWEVER, IS LIKELY TO INCREASE FROM
SUNDAY THROUGH MONDAY, DUE TO AN ENHANCEMENT IN MOISTURE.
AN UPPER LEVEL TROUGH AND A LOW-LEVEL TROUGH WILL CAUSE RAINFALL
OVER HONDURAS AND NICARAGUA, FROM TODAY THROUGH SATURDAY.
PRECIPITATION WILL INCREASE FROM SUNDAY THROUGH MONDAY AS A PLUME
OF MOISTURE AND LOW-LEVEL TROUGH REACH THE AREA. PRECIPITATION
TOTALS AROUND 15-25MM ARE EXPECTED EACH DAY.
IN COSTA RICA, AND PANAMA THE MONSOON TROUGH WILL ENHANCE
CIRCULATION OVER THE CARIBBEAN INTO THE REGION THAT WILL FAVOR AN
INCREASE OF MOISTURE ONSHORE, BRINGING PRECIPITATION EACH DAY.
WITH THE DEVELOPMENT OF THE CARIBBEAN LOW LEVEL JET ON SUNDAY, AN
INCREASE IN PRECIPITATION IS EXPECTED AS THE FLOW CAN ENHANCE
OROGRAPHIC LIFTING IN THE AREA.
TROPICAL SOUTH AMERICA:
HEAVY RAINFALL IS EXPECTED FROM SATURDAY THROUGH MONDAY OVER THE
WESTERN COAST OF COLOMBIA, WITH LOW-LEVEL WESTERLY FLOW ADVECTING
MOISTURE FROM THE PACIFIC OCEAN. IN NORTHEASTERN SOUTH AMERICA, A
PLUME OF MOISTURE ASSOCIATED WITH THE ITCZ IS EXPECTED TO CAUSE
PRECIPITATION OVER GUYANA AND VENEZUELA, AND THE COAST OF
SURINAME. THE PLUME OF MOISTURE IS PROJECTED TO PERSIST IN THE
AREA OVER THE FORECAST PERIOD, THEREFORE, SHOWERS ARE EXPECTED
EACH DAY.
CONVECTIVE ACTIVITY AND THUNDERSTORMS ARE EXPECTED ACROSS THE REST
OF THE REGION. THESE WILL PRIMARILY BE DRIVEN BY MOISTURE
ADVECTION, LOW-LEVEL MOISTURE CONVERGENCE, DIURNAL HEATING, AND
CONVECTIVELY INDUCED TROUGHS. AN UPPER LEVEL TROUGH DEVELOPING
OVER THE WESTERN PORTION OF THE REGION, WILL INCREASE UPPER-LEVEL
DIFFLUENCE OVER THE AMAZON REGION, LEADING TO HIGHER TOTALS OF
PRECIPITATION FROM SATURDAY THROUGH MONDAY.
POSITIONS OF TROPICAL/EASTERLY WAVES INITIALIZED AT 12 UTC
TYP SOF INIT 22/00 22/12 23/00 23/12 24/00 24/12 25/00
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