099
FXCA20 KWBC 121648
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1148 AM EST FRI DEC 12 2025
FORECAST BULLETIN 12 DECEMBER 2025 AT 1650 UTC:
A POTENT SURFACE-TO-LOW LEVEL RIDGE IS CURRENTLY EXTENDING ACROSS
THE CENTRAL GULF AND WILL PROMOTE AN INCREASE IN EASTERLY LOW
LEVEL WINDS ACROSS THE YUCATAN PENINSULA BEGINNING ON FRIDAY.
EMBEDDED WITHIN THIS WIND REGIME IS A SLOWING LOW LEVEL TROUGH
THAT IS CURRENTLY MOVING ACROSS THE YUCATAN PENINSULA AND WILL
LOSE ITS DEFINITION AS IT CONTINUES TO INTERACT WITH THE BROAD
RIDGE. ITS MOISTURE PLUME WILL CONTINUE TO AFFECT THE CARIBBEAN
COAST OF THE PENINSULA AND DIURNAL AND LOCAL EFFECTS WILL FAVOR
THE DEVELOPMENT OF COASTAL SHOWERS AND THUNDERSTORMS FOR FRIDAY.
BEGINNING FRIDAY EVENING, A SHORTWAVE MID-LEVEL TROUGH WILL ALSO
BEGIN TO DEVELOP OVER THE YUCATAN CHANNEL. THIS SHORTWAVE TROUGH
WILL CONTINUE MOVING IN A NORTHEAST DIRECTION, ARRIVING INTO
WESTERN CUBA ON SATURDAY AFTERNOON AND MOVING INTO THE STRAITS OF
FLORIDA BY SUNDAY. THIS FEATURE WILL HELP DESTABILIZE THE
ENVIRONMENT AND MAY PROVIDE ADDITIONAL VERTICAL ASCENT. WITH
RESPECT TO PRECIPITATION, THE GREATEST IMPACTS ON FRIDAY WILL BE
CENTRALIZED ACROSS QUINTANA ROO AND BELIZE. BY SATURDAY, THE AREA
OF GREATEST IMPACT WILL BE NORTHWEST CUBA AND BAHAMAS IN THE
VICINITY OF THE MID-LEVEL SHORTWAVE TROUGH AND THE PROJECTED LOW
LEVEL TROUGH. THIS MID-LEVEL TROUGH WILL BE EXITING THE REGION BY
SUNDAY. NOTE THAT THERE IS ALSO A SURFACE STATIONARY FRONT THAT
WILL BE DRAPING ACROSS THE NORTHWEST BAHAMAS AND CUBA ON FRIDAY
AND WILL ENHANCE LOW LEVEL MOISTURE CONVERGENCE. THIS FRONT WILL
BEGIN TO LOSE ITS DEFINITION ON SATURDAY.
ANOTHER POTENT COLD FRONT WILL BE MOVING ACROSS THE GULF REGION
STARTING SUNDAY AND INTO EARLY NEXT WEEK. ON SUNDAY EVENING, THIS
COLD FRONT WILL BE LOCATED ACROSS NORTHERN TAMAULIPAS, COAHUILA,
AND CHIHUAHUA. AS THIS COLD FRONT ADVANCES SOUTHWARD, EXPECT
INCREASED EASTERLY AND NORTH-EASTERLY LOW LEVEL WINDS AHEAD OF THE
BOUNDARY INTO THE FOOTHILLS OF THE SIERRA MADRE IN NUEVO LEON,
TAMAULIPAS, AND VERACRUZ. THIS WILL ENABLE AN INCREASE IN MOISTURE
CONVERGENCE AND OROGRAPHIC EFFECTS. THE ADDITIONAL LIFT PROVIDED
BY THE PRESENCE OF THE COLD FRONT AND MOISTURE CONVERGENCE WILL
PROMOTE A TOTAL PRECIPITATION MAXIMA OF 30 - 60MM ACROSS NUEVO
LEON AND TAMAULIPAS FROM SUNDAY MORNING THROUGH SATURDAY MORNING.
ACROSS NORTHERN VERACRUZ, A TOTAL PRECIPITATION MAXIMA OF 25 -
50MM IS LIKELY FOR THE SAME PERIOD, BUT THIS REGION WILL REMAIN
SOUTH OF THE COLD FRONT. PERSISTENT NORTHEASTERLY LOW LEVEL FLOW
WILL ALSO ENHANCE MOISTURE CONVERGENCE ACROSS SOUTHERN VERACRUZ
AND WILL YIELD A TOTAL PRECIPITATION MAXIMA OF 20 - 45MM FOR
SUNDAY INTO MONDAY.
IN CENTRAL AMERICA, THE CARIBBEAN LOW LEVEL JET WILL CONTINUE TO
DOMINATE IN THE REGION AND WILL FAVOR INCREASING LOW LEVEL
CYCLONIC CIRCULATION ACROSS SOUTHERN NICARAGUA, COSTA RICA, AND
PANAMA. AT THE SAME TIME, THE MONSOON TROUGH AND PANAMANIAN LOW
LEVEL JET WILL BE INFLUENCING THE LOW LEVEL WIND REGIME, FURTHER
ENHANCING LOW LEVEL CYCLONIC CIRCULATION. THE INCREASE IN MOISTURE
POOLING INTO THE CARIBBEAN COASTS OF NICARAGUA AND COSTA RICA WILL
FAVOR INCREASED PRECIPITATION ACCUMULATIONS FOR SATURDAY AND
SUNDAY. THE PASSAGE OF LOW LEVEL TROUGHS IN THE TRADE WINDS WILL
TRIGGER THE INTENSIFICATION OF THE PANAMANIAN LOW LEVEL TROUGH ON
SATURDAY. DAILY TOTAL PRECIPITATION MAXIMA WILL INCREASE FOR THE
WEEKEND, WHERE IT WILL LIKELY EXCEED 50MM FOR BOTH DAYS. ACROSS
THE PACIFIC COAST OF COLOMBIA, ACCUMULATIONS WILL REMAIN ON THE
MODERATE SIDE AS THERE WILL BE LIMITED ONSHORE FLOW. THE LOW LEVEL
WIND FLOW WILL ALSO BE VERY WEAK AND IF ANY CONVECTION DOES
DEVELOP, IT WILL BE ATTRIBUTED TO LOCAL EFFECTS AND THE DIURNAL
CYCLE. MEANWHILE IN CENTRAL COLOMBIA, THERE WILL BE AN INCREASE IN
MOISTURE AND NORTHERLY LOW LEVEL WINDS INTO THE VALLE DE MAGDALENA
FOR SATURDAY AND SUNDAY THAT WILL INCREASE PRECIPITATION CHANCES
IN THIS REGION. DAILY TOTAL PRECIPITATION MAXIMA WILL EXCEED 25MM
ON BOTH DAYS.
ACROSS THE AMAZON BASIN, THE NOCTURNAL LOW LEVEL JET WILL CONTINUE
TO DRIVE PRECIPITATION PROCESSES IN THIS REGION FOR THE NEXT THREE
DAYS. LOW LEVEL CYCLONIC CIRCULATION WILL BE ENHANCED ACROSS THE
SOUTHWEST AND CENTRAL AMAZON BASIN WITH A DRYING TREND ACROSS THE
WESTERN AMAZON BASIN. NOTE THAT THE NOCTURNAL JET WILL TEMPORARILY
DECREASE IN INTENSITY FOR SUNDAY. PRECIPITATION ACCUMULATIONS WILL
BE ON THE MODERATE SIDE ACROSS THIS REGION. ELSEWHERE, IN THE
GUIANAS AND THE AMAZON DELTA, A LONG FETCH MOISTURE PLUME WILL
CONTINUE TO CONVERGE WITH THE AREA FOR THE ENTIRETY OF THE
FORECAST CYCLE, BUT AVAILABLE MOISTURE WILL DECREASE SLIGHTLY
ACROSS THE GUIANAS FOR SUNDAY. THUS, THE PERIOD WITH THE GREATEST
PRECIPITATION IMPACTS WILL BE ON FRIDAY AND SATURDAY. SOME UPPER
LEVEL DIVERGENCE MAY BE PRESENT IN THE REGION BUT WILL BE
PRIMARILY DRIVEN BY CONVECTIVE OUTFLOWS. THE HIGHEST PRECIPITATION
ACCUMULATIONS WILL BE LOCATED IN THE AMAZON DELTA AND FRENCH
GUIANA.
ACROSS THE CARIBBEAN, THE LOW LEVEL TRADE WINDS WILL DOMINATE IN
THE REGION. EMBEDDED WITHIN THIS FLOW WILL BE A SERIES OF LOW
LEVEL TROUGHS AND MOISTURE PLUMES THAT WILL CONVERGE WITH THE
ISLANDS. IN GENERAL, EXPECT ACCUMULATIONS UP TO 10MM ACROSS THE
ENTIRE REGION WITH THE PASSAGE OF THESE TROUGHS. THE LOW LEVEL
WIND FLOW PATTERN WILL BEGIN TO CHANGE ACROSS THE GREATER ANTILLES
STARTING ON SUNDAY AFTERNOON WITH THE ARRIVAL OF THE
AFOREMENTIONED POTENT COLD FRONT. OTHERWISE, LOCAL EFFECTS, THE
DIURNAL CYCLE, AND OROGRAPHIC ENHANCEMENT WILL FURTHER SUPPORT THE
INITIATION AND SUSTENANCE OF SHOWERS AND CONVECTION ACROSS THE
GREATER AND LESSER ANTILLES.
POSITIONS OF TROPICAL/EASTERLY WAVES INITIALIZED AT 12 UTC
TYP SOF INIT 13/00 13/12 14/00 14/12 15/00 15/12 16/00
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