112
FXCA20 KWBC 151757
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1256 PM EST MON DEC 15 2025
FORECAST BULLETIN 15 DECEMBER 2025 AT 1800 UTC:
OVER MOST OF THE FORECAST REGION, MODEL GUIDANCE IS SUGGESTING
THAT A DISORGANIZED UPPER DIVERGENCE PATTERN IS EXPECTED
THROUGHOUT THE FORECAST PERIOD DUE TO THE PRESENCE OF THE
DIVERGENT PHASE MADDEN-JULIAN OSCILLATION OR AN ATMOSPHERIC KELVIN
WAVE. THIS CONDITION MAY HELP VENTILATE CONVECTION OVER AREAS
WHERE DEEP CONVECTION IS EXPECTED. LOCALLY HIGHER PRECIPITATION
TOTALS ARE POSSIBLE IN AREAS THAT ARE FORECAST TO SEE
PRECIPITATION.
OVER MEXICO, A GENERALIZED RIDGING PATTERN IS EXPECTED THAT
EXTENDS OVER MOST OF CENTRAL AND SOUTHERN MEXICO, WHILE POSITIONED
BETWEEN TWO TROUGHS, TO ITS EAST, A POTENT, WIDE TROUGH OVER THE
SOUTHERN UNITED STATES AND INTO THE NORTH CARIBBEAN, AND TO THE
WEST, A SHORTWAVE TROUGH ENTERING THE NORTHERN BAJA CALIFORNIA
PENINSULA. A COLD FRONT ASSOCIATED WITH THE EASTERN UPPER LEVEL
TROUGH ENTERS NORTHEAST MEXICO AND IT IS EXPECTED OVER CENTRAL
VERACRUZ AND ALONG THE SIERRA MADRE ORIENTAL BY MONDAY EVENING.
WITH THE FRONTAL BOUNDARY IN VERACRUZ, EXPECT MOISTURE ALONG THE
COASTAL REGION TO CONVERGE AS THE FRONTAL BOUNDARY INTERACTS WITH
THE TERRAIN. THE REGION COULD EXPECT MAXIMA OF 30-60MM, WHILE THE
REST OF NORTH AND CENTRAL VERACRUZ CAN EXPECT MAXIMA OF 20-45MM.
ON TUESDAY, THE UPPER LEVEL CONDITIONS ARE EXPECTED TO REMAIN,
WHILE IN THE LOWER LEVELS, THE FRONTAL BOUNDARY HAS WEAKENED AND
REMNANTS OF MOISTURE ARE EXPECTED IN NORTHEAST MEXICO. THESE
CONDITIONS WILL IN TURN, FAVOR A DECREASE IN PRECIPITATION IN THE
REGION, WHERE LOCALIZED SHOWERS ARE EXPECTED TO PRODUCE TRACE
AMOUNTS OF TOTAL PRECIPITATION ON TUESDAY. BY WEDNESDAY, A NEW
UPPER LEVEL TROUGH IS EXPECTED OVER THE CENTRAL UNITED STATES, AND
ITS BASE IS EXPECTED TO REACH INTO SOUTHWEST MEXICO BY WEDNESDAY
EVENING. THIS NEW SYSTEM WILL FAVOR A SHIFT IN WIND PATTERNS IN
THE LOWER LEVELS, AS MOISTURE ASSOCIATED WITH THE REMNANTS OF THE
AFOREMENTIONED COLD FRONT ALONG NORTHEASTERN MEXICO IS ADVECTED
NORTHWARD AND IT IS EXPECTED TO REMAIN ALONG COASTAL TAMAULIPAS
AND NORTH VERACRUZ ON WEDNESDAY. EXPECT MAXIMA IN THE REGION TO
REMAIN BELOW 15MM.
IN CENTRAL AMERICA, THE NORTHERN PORTION OF THE REGION IS SEEING
MOISTURE CONVERGENCE ALONG THE CONFLUENCE OF LOW LEVEL WINDS
ASSOCIATED WITH THE EASTERLY TRADE WINDS INTERACTING WITH THE
PRESENCE OF THE FRONTAL BOUNDARY ENTERING THE NORTHERN CARIBBEAN
ON MONDAY. TO THE SOUTH, FROM SOUTHERN NICARAGUA THROUGH PANAMA,
THE MONSOON TROUGH REMAINS OVER THE REGION, FAVORING CONVECTION.
THE SOUTHERN REGION OF CENTRAL AMERICA IS EXPECTING AVAILABLE
MOISTURE TO REMAIN AT AROUND 50-60MM ON MONDAY, AND A SLIGHT
DECREASE IS EXPECTED INTO TUESDAY AND WEDNESDAY AS THE EASTERLY
TRADE WINDS ARE ADVECTING DRIER AIR OVER THE CARIBBEAN SEA. IN THE
UPPER LEVELS, THE UPPER LEVEL TROUGH EXTENDS OVER THE NORTH
CARIBBEAN, AND IT IS REFLECTED IN THE MID LEVELS, WHERE SHORT WAVE
TROUGHS ARE EXPECTED OVER THE GULF OF HONDURAS ON MONDAY. WITH THE
CONDITIONS OVER THE REGION, MONDAY IS EXPECTED TO BE THE DAY WITH
HEAVIER PRECIPITATION TOTALS. ON TUESDAY, THE MID TO UPPER LEVEL
TROUGH PROPAGATES EASTWARD, GIVING WAY TO THE DEVELOPMENT OF A
MID-LEVEL RIDGE EXTENDING OVER THE CARIBBEAN SEA AND INTO CENTRAL
AMERICA BY WEDNESDAY EVENING. A GENERALIZED DECREASE IS EXPECTED
ON TUESDAY AND WEDNESDAY OVER CENTRAL AMERICA. ON MONDAY,
NORTHWEST HONDURAS CAN EXPECT MAXIMA OF 35-70MM, WHILE THE REST OF
NORTH HONDURAS, AND FROM BELIZE TO CENTRAL GUATEMALA, CAN EXPECT
MAXIMA OF 20-35MM. COSTA RICA AND PANAMA CAN EXPECT GENERALIZED
MAXIMA OF 20-45MM ON MONDAY. ON TUESDAY, FROM THE BOCAS DEL TORO
REGION TO SOUTHEAST COSTA RICA, EXPECT MAXIMA OF 25-50MM, WHILE
THE REST OF THE COSTA RICA AND PANAMA CAN EXPECT GENERALIZED
MAXIMA OF 15-25MM. SIMILAR AMOUNTS ARE EXPECTED FROM THE EASTERN
YUCATAN PENINSULA TO BELIZE, AND FROM EAST HONDURAS THROUGH EAT
NICARAGUA. ON WEDNESDAY, THE DECREASE IN AVAILABLE MOISTURE IS
PRESENT AND THUS THE REGION CAN EXPECT GENERALIZED AND LOCAL
MAXIMA OF 15-20MM.
OVER THE CARIBBEAN REGION AND THE BAHAMAS, A DRY TREND IS EXPECTED
OVER THE NEXT THREE DAYS, WITH MONDAY BEING THE DAY WITH HEAVIEST
PRECIPITATION. THE PRESENCE OF THE AFOREMENTIONED UPPER LEVEL
TROUGH IS EXPECTED TO REMAIN IN THE NORTH CARIBBEAN, WHILE IN THE
LOWER LEVELS, THE FRONTAL BOUNDARY IS EXPECTED TO EXTEND FROM THE
CENTRAL ATLANTIC OCEAN AND INTO THE CENTRAL BAHAMAS AND NORTH OF
CUBA BY MONDAY EVENING. DRY AIR IS BEING ADVECTED IN THE EASTERLY
TRADE WINDS OVER THE CARIBBEAN SEA, AND IT IS EXPECTED TO CONTINUE
INTO WEDNESDAY. ON TUESDAY, THE FRONTAL BOUNDARY WEAKENS OVER THE
BAHAMAS, WITH REMNANT TROUGHS AND MOISTURE OVER CUBA. BY
WEDNESDAY, A MID-LEVEL RIDGE DEVELOPS OVER THE CARIBBEAN SEA
EXTENDING INTO THE NORTH CARIBBEAN AND THE BAHAMAS, FAVORING A
TRADE WIND INVERSION CAPS OVER THE REGION, AND A DECREASE IN
PRECIPITATION TOTALS. ON MONDAY, EXPECT MAXIMA OF 20-35MM IN
CENTRAL AND SOUTH BAHAMAS WITH A SLIGHT RISK OF SEVERE WEATHER,
WHILE NORTHERN BAHAMAS CAN EXPECT MAXIMA OF 15-25MM WITH A
MARGINAL RISK OF SEVERE WEATHER. SIMILAR TOTALS ARE EXPECTED ALONG
THE NORTHERN SHORES OF CUBA. THE REST OF THE GREATER AND LESSER
ANTILLES CAN EXPECT LOCAL MAXIMA TO REMAIN BELOW 15MM. ON TUESDAY,
THE NORTH BAHAMAS AND NORTHWEST CUBA CAN EXPECT MAXIMA OF 20-35MM
WITH THE WEAKENING FRONT AND REMNANT TROUGHS IN THE REGION. BY
WEDNESDAY, LOCAL SHOWERS WITH A CHANCE OF TRACE AMOUNTS ARE
EXPECTED OVER THE CARIBBEAN, WITH THE POTENTIAL FOR MAXIMA OF 10MM
IN THE SOUTH BAHAMAS AND TURKS AND CAICOS, AS WELL AS IN THE
LESSER ANTILLES.
THE NORTH OF SOUTH AMERICA CAN EXPECT TO SEE THE POTENTIAL FOR THE
DIURNAL CYCLE AND THE PRESENCE OF A MOIST PLUME OVER THE ATLANTIC
OCEAN ENTERING THE CONTINENT TO ASSIST WITH PRECIPITATION OVER THE
NEXT THREE DAYS. PRECIPITATION TOTALS ARE EXPECTED TO REMAIN LIGHT
TO MODERATE IN A LOCAL LEVEL, EXCEPT ALONG THE EASTERN SHORES OF
FRENCH GUIANA AND THE AMAPA-BRASIL. THE NOCTURNAL LLJ IS EXPECTED
TO BRING DRY CONDITIONS OVER VENEZUELA AND EAST COLOMBIA FROM
MONDAY THROUGH EARLY THURSDAY, WHILE CONTINUOUS ONSHORE FLOW
ASSOCIATED WITH A MOIST PLUME ENTERING THE REGION OF FRENCH GUIANA
AND AMAPA IN AN ALMOST PERPENDICULAR MANNER, AND WITH HIGH WIND
SPEEDS. THESE CONDITIONS ARE EXPECTED OVER THE FORECAST PERIOD,
GIVING THE POTENTIAL FOR LOCALIZED ECHO TRAINING OVER THE NEXT
THREE DAYS. ON MONDAY, MOST OF THE REGION CAN EXPECT MAXIMA OF
15-25MM, WHILE FROM THE FRENCH GUIANA TO AMAPA, EXPECT MAXIMA OF
25-45, WITH A POTENTIAL FOR LOCALLY HIGHER TOTALS. ON TUESDAY, A
SLIGHT INCREASE ON PRECIPITATION IN NORTH PERU WITH THE MOISTURE
CONVERGING IN THE WESTERN AMAZON BASIN. IN THE FRENCH GUIANA AND
AMAPA-BRASIL, EXPECT MAXIMA OF 25-50MM. ON WEDNESDAY, EXPECT
SIMILAR TOTAL PRECIPITATION OVER THE REGION, WHILE FRENCH GUIANA
AND AMAPA CAN EXPECT MAXIMA OF 20-45MM.
POSITIONS OF TROPICAL/EASTERLY WAVES INITIALIZED AT 12 UTC
TYP SOF INIT 16/00 16/12 17/00 17/12 18/00 18/12 19/00
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