741
FXCA20 KWBC 182046
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
346 PM EST MON NOV 18 2024
FORECAST BULLETIN 18 NOV 2024 AT 2030 UTC:
A SURFACE HIGH PRESSURE ACROSS THE WESTERN TROPICAL ATLANTIC WILL
DOMINATE MOST OF THE CARIBBEAN WEATHER PATTERN...BRINGING DRY AIR
TO THE NORTHERN LEEWARDS AND THE GREATER ANTILLES TODAY AND
TUESDAY. THERE IS ALSO A SERIES OF FRONTAL BOUNDARIES THAT WILL BE
AFFECTING THE TROPICAL REGION OVER THE NEXT FEW DAYS...WHICH MAY
HAVE AN IMPACT ON THE RAINFALL DEVELOPMENT OVER THE AREA.
ACROSS THE TROPICAL ATLANTIC...A STATIONARY FRONT EXTENDING INTO
THE NORTHEASTERN ATLANTIC WILL REMAIN IN PLACE AS IT WEAKENS ON
TUESDAY...DISSIPATING BY WEDNESDAY. THERE IS A PRE-FRONTAL SHEAR
LINE THAT WILL EXTEND INTO THE CENTRAL CARIBBEAN...AND A SURFACE
TROUGH THAT IS EXPECTED TO PREVAIL TODAY AND TUESDAY OVER THE
EASTERN CARIBBEAN...CAUSING SOME RAINFALL OVER THE SOUTHERN
LEEWARD ISLANDS INTO THE WINDWARD ISLANDS TODAY AND TUESDAY. TRADE
WIND SHOWERS MAY AFFECT THE LESSER ANTILLES ON WEDNESDAY...BUT THE
AMOUNTS ARE EXPECTED TO BE UNDER 25MM.
ANOTHER SET OF FRONTAL BOUNDARIES ARE EXPECTED TO MOVE
SOUTH...THIS TIME ACROSS THE GULF OF MEXICO INTO THE EASTERN COAST
OF MEXICO. A COLD FRONT WILL BE JUST OVER THE NORTHWESTERN GOLF OF
MEXICO THIS EVENING...THEN IT WILL MOVE SOUTHEAST INTO THE CENTRAL
GULF OF MEXICO BY TUESDAY EVENING...EXTENDING SOUTHWARD INTO THE
YUCATAN PENINSULA...AS WELL AS THE GULF COAST OF SOUTHERN MEXICO
BY WEDNESDAY EVENING. AS THE FRONTAL BOUNDARY MOVES
SOUTH...INTERACTIONS WITH THE LOCAL TOPOGRAPHY WILL HAVE AN IMPACT
ON THE AMOUNT OF RAIN OVER THE AREA. NORTHERN VERACRUZ COULD
OBSERVE SOME RAINFALL ON TUESDAY INTO WEDNESDAY...UP TO 40MM AS
THE COLD FRONT APPROACHES THE AREA. HOWEVER...HIGHER AMOUNTS OF
RAIN ARE FORECAST ON WEDNESDAY INTO THURSDAY ACROSS SOUTHERN
MEXICO AND PORTIONS OF GUATEMALA...WITH MAX VALUES GENERALLY
AROUND 20-30MM...BUT PORTIONS OF CHIAPAS...TABASCO..AND SOUTHERN
VERACRUZ COULD OBSERVE UP TO 60MM.
THE RAINFALL FORECAST OVER CENTRAL AMERICA IS HIGHLY INFLUENCED BY
THE PRESENCE OF THE ITCZ/MONSOON TROUGH WHICH IS EXPECTED TO BE
PRESENT ALONG THE PACIFIC COAST OF CENTRAL AMERICA TONIGHT. THIS
WILL CAUSE DEEP MOISTURE TO MOVE INTO THE PACIFIC COASTLINE OF
CENTRAL AMERICA FOR THE REST OF TODAY INTO TUESDAY...ESPECIALLY
FOR SOUTHERN GUATEMALA AND HONDURAS...WITH MAX RAINFALL TOTALS
NEAR 25-50MM. THAT BEING SAID...THE ITCZ WILL SLOWLY MOVE AWAY
FROM THE PACIFIC COAST OF NORTHERN CENTRAL AMERICA FROM TUESDAY
ONWARD...THOUGH REMAIN PRESENT OVER COSTA RICA AND PANAMA. THIS
WILL CAUSE RAINFALL POTENTIAL OVER THE SOUTHERN PORTIONS OF
CENTRAL AMERICA...WITH PARTICULAR EMPHASIS ON THE PACIFIC COAST OF
COSTA RICA AND PANAMA...WHERE THE HIGHER AMOUNTS OF RAIN ARE
FORECAST...WITH MAX VALUES UP TO 35MM.
NORTHERN SOUTH AMERICA WILL HAVE A DIURNALLY INFLUENCED RAINFALL
AND THUNDERSTORM PATTERN...WITH MOST OF THE THUNDERSTORM
DEVELOPMENT OCCURRING IN THE AFTERNOON HOURS OF NORTHERN SOUTH
AMERICA. HOWEVER...WESTERN COLOMBIA WILL HAVE DAILY SHOWERS AND
THUNDERSTORMS AS ONSHORE DEEP MOISTURE INTERACTS WITH THE LOCAL
TERRAIN. THE MODEL GUIDANCE IS IN DISAGREEMENT IN THE AMOUNTS OF
RAIN...WITH SOME MODELS SUGGESTING VERY HIGH RAINFALL AMOUNTS
COMPARED TO OTHER GLOBAL MODELS. AT THIS TIME...THE ECMWF MODEL
SEEMED TO HAVE A GOOD GRASP ON THE CONVECTION COMPARED TO OTHER
GLOBAL MODELS...FOR THAT REASON WE DECIDED TO SPLIT THE DIFFERENCE
IN THE RAINFALL FORECAST FOR WESTERN COLOMBIA...BUT GIVING A
SLIGHT EDGE TO THE ECMWF MODEL. FOR THAT REASON...THE DAILY MAX
RAINFALL FORECAST IS BETWEEN 30-60MM TODAY INTO TUESDAY MORNING.
IT MAY PAY TO KNOW THAT MOST OF THE RAINFALL OVER WESTERN COLOMBIA
IS ACTUALLY EXPECTED TO OCCUR VERY LATE TONIGHT INTO TUESDAY
MORNING. THEREAFTER...MAX RAINFALL TOTALS...UP TO 40MM ARE
FORECAST FOR WESTERN COLOMBIA. OTHER SECTORS IN NORTHER SOUTH
AMERICA ARE FORECAST TO HAVE SCATTERED THUNDERSTORMS WITH DAILY
RAINFALL TOTALS AROUND 25 TO 35MM.
EASTERLY/TROPICAL WAVES INITIALIZED AT 12 UTC
NONE
ALAMO...(WPC)
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