250
FXCA20 KWBC 191938
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
238 PM EST TUE NOV 19 2024
FORECAST BULLETIN 19 NOV 2024 AT 1930 UTC:
A SURFACE HIGH PRESSURE ACROSS THE WESTERN TROPICAL
ATLANTIC...CENTERED JUST NORTHEAST OF THE NORTHERN BAHAMAS WILL
DOMINATE MOST OF THE CARIBBEAN WEATHER PATTERN TODAY AND WEDNESDAY
AS IT MOVES EAST. THE HIGH PRESSURE IS EXPECTED TO BE CENTERED
OVER THE CENTRAL TROPICAL ATLANTIC BY THURSDAY...THOUGH ELONGATING
WEST INTO THE WESTERN TROPICAL ATLANTIC. IN ADDITION...THIS HIGH
PRESSURE WILL CONTINUE TO BRING DRIER THAN NORMAL MOISTURE TO THE
GREATER ANTILLES THROUGH THURSDAY. HOWEVER...A BAND WITH HIGHER
THAN NORMAL MOISTURE WILL START MOVING IN FROM THE WEST INTO
WESTERN CUBA ON WEDNESDAY. THIS BAND OF MOISTURE IS ASSOCIATED
WITH A COLD FRONT THAT WILL BE MOVING EAST THROUGH THE GULF OF
MEXICO...REACHING EASTERN MEXICO TODAY...THEN ALONG THE YUCATAN
PENINSULA AND WESTERN CUBA ON WEDNESDAY INTO THURSDAY...THEN
REACHING FROM THE CENTRAL BAHAMAS TO CENTRAL CUBA SOUTH INTO
NICARAGUA AND HONDURAS THURSDAY INTO FRIDAY. MUCH DRIER THAN
NORMAL MOISTURE WILL BE MOVING IN BEHIND THE COLD FRONT.
THERE ARE MID AND UPPER LEVEL HIGH PRESSURES CAUSING RELATIVELY
STABLE CONDITIONS OVER THE WESTERN CARIBBEAN INTO THE GULF OF
MEXICO...THOUGH SOME SHOWERS AND ISOLATED THUNDERSTORMS ARE
POSSIBLE OVER EASTERN MEXICO INTO THE YUCATAN PENINSULA AND
NORTHERN CENTRAL AMERICA. THAT BEING SAID...THE HEAVIER
PRECIPITATION WILL BE OVER LAND AREAS AS THE AFOREMENTIONED
FRONTAL BOUNDARY AND DEEP MOISTURE INTERACTS WITH THE LOCAL
TERRAIN TODAY AND WEDNESDAY. THE INTERACTION OF THE FRONTAL
BOUNDARY AND INCREASE IN MOISTURE WILL CAUSE SHOWERS AND
THUNDERSTORMS ACROSS PORTIONS OF EAST CENTRAL MEXICO TODAY INTO
WEDNESDAY MORNING...WITH FORECAST TOTALS MAXING OUT AT
25-50MM...THEN 30-60MM OF RAIN ARE FORECAST FOR AREAS FROM
VERACRUZ SOUTHEAST INTO SOUTHERN MEXICO AND NORTHERN GUATEMALA ON
WEDNESDAY INTO THURSDAY. TROUGHS IN THE MID AND UPPER LEVELS WILL
BE DIGGING INTO THE GULF OF MEXICO ON THURSDAY INTO FRIDAY. THE
FORECAST RAINFALL FOR THURSDAY INTO FRIDAY ACROSS NORTHERN
HONDURAS SUGGESTS MAX VALUES OF 50-100MM...UNFORTUNATELY WHERE
THEY RECENTLY RECEIVED VERY SIGNIFICANT RAINFALL WITH FORMER
TROPICAL STORM SARA. THE COMBINATION OF THE MID LEVEL TROUGH WITH
DIVERGENCE ALOFT...DEEP MOISTURE AHEAD OF A COLD FRONT AND ALONG A
DYING FRONTAL BOUNDARY...WITH THE INTERACTION WITH THE LOCAL
TERRAIN IS THE REASON FOR THE HIGH RAINFALL FORECAST.
THE LESSER ANTILLES WILL HAVE IN GENERAL NORMAL TO SLIGHTLY ABOVE
NORMAL MOISTURE OVER THE NEXT FEW DAYS. THIS IS DUE TO A
COMBINATION OF A DYING STATIONARY FRONT THAT IS EXTENDING FROM THE
CENTRAL ATLANTIC INTO THE LESSER ANTILLES TODAY...WHILE A SFC
TROUGH IS EXPECTED TO REMAIN OVER THE EASTERN CARIBBEAN FOR THE
NEXT FEW DAYS. THERE IS ALSO A BROAD UPPER AND MID LEVEL TROUGHS
IN THE ATLANTIC THAT ARE REACHING THE CARIBBEAN TODAY...WHICH IS
CAUSING SOME CONVECTION AROUND THE WINDWARD ISLANDS AND JUST EAST
IF THE ISLANDS. LOW-LEVEL MOISTURE CONVERGENCE OVER THE LESSER
ANTILLES WILL PREVAIL FOR THE NEXT FEW DAYS...WHICH WILL HELP
CAUSE SOME SHOWER ACTIVITY OVER THE AREA EACH DAY...THOUGH THE
AMOUNTS WILL BE GENERALLY UNDER 20MM.
MOST OF CENTRAL AMERICA IS EXPECTED TO OBSERVE RAIN EACH DAY OVER
THE NEXT 3 DAYS...WITH THE DAILY RAINFALL AMOUNTS FORECAST TO MAX
OUT AT 15-35MM TODAY AND WEDNESDAY...WITH THE EXCEPTION OF THE
AFOREMENTIONED RAINFALL OVER NORTHERN CENTRAL AMERICA WITH THE
APPROACHING COLD FRONT. THE ITCZ/MONSOON TROUGH IS FORECAST TO BE
PRESENT THROUGH COSTA RICA OVER THE NEXT FEW DAYS...CAUSING SOME
SHOWERS AND THUNDERSTORMS ACROSS SOUTHERN CENTRAL AMERICA...THOUGH
THE LATEST GUIDANCE STILL INSISTS ON DAILY RAINFALL TOTALS UNDER
25MM TODAY AND WEDNESDAY...THE RAINFALL COULD BE AS HIGH AS 40MM
ON THURSDAY INTO FRIDAY.
NORTHERN SOUTH AMERICA WILL ONCE AGAIN RECEIVE DAILY SHOWERS AND
THUNDERSTORMS WHICH WILL BE HIGHLY INFLUENCED BY THE DIURNAL
HEATING INTERACTING WITH THE LOCAL TERRAIN AND THE PRESENCE OF SFC
TROUGHS. MOST OF THE DAILY RAINFALL TOTALS WILL MAX OUT AT AROUND
20-40MM...THOUGH A SMALL AREA OF NORTHERN PERU INTO SOUTHWESTERN
COLOMBIA AND NORTHWESTERN BRAZIL IS FORECAST TO OBSERVE UP TO 50MM
ON THURSDAY INTO FRIDAY. WESTERN COLOMBIA HAS A CHANCE OF
SIGNIFICANT RAINFALL...EACH DAY MAXING OUT NEAR 60MM. IN
FACT...THE ECMWF MODEL IS BEING VERY BULLISH WITH THE RAINFALL
FORECAST FOR WESTERN COLOMBIA...THOUGH OUR FORECAST HAS AVERAGED
THE DIFFERENT MODEL OUTPUTS...AND THEREFORE SUGGEST AMOUNTS UNDER
WHAT THE ECMWF MODEL SUGGESTS...BUT HIGHER THAN OTHER MODELS...THE
GFS MODEL WAS PARTICULARLY DRY. WESTERN COLOMBIA HAS A GOOD CHANCE
OF PERSISTENT RAINFALL DUE TO THE ONSHORE FLOW OF DEEP MOISTURE
FROM THE PACIFIC INTO THE WEST COAST OF COLOMBIA...WHICH WILL THEN
INTERACT WITH THE LOCAL TERRAIN.
EASTERLY/TROPICAL WAVES INITIALIZED AT 12 UTC
NONE
ALAMO...(WPC)
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