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FXCA20 KWBC 251836
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
235 PM EDT WED SEP 25 2024
FORECAST BULLETIN 25 SEP 2024 AT 1830 UTC:
IN THE WESTERN CARIBBEAN...HURRICANE HELENE IS LOCATED NEAR 21.6N
AND 86.3W AT 15 UTC ON WEDNESDAY. THE NATIONAL HURRICANE CENTER IS
FORECASTING A FAST MOVEMENT TOWARDS THE NORTH OVER THE NEXT
SEVERAL DAYS. FOR THE PORTIONS OF WEST CUBA AND EAST YUCATAN...IT
MEANS THAT THE IMPACT FROM THE STORM ARE EXPECTED PRIMARILY ON
WEDNESDAY AND THURSDAY...WITH DECREASED EFFECTS EXPECTED ON
FRIDAY. THE UPPER LEVEL TROUGH OVER THE NORTHERN GULF OF
MEXICO...AND THE RIDGE TO THE NORTHEAST OVER THE BAHAMAS AND INTO
THE NORTHERN ATLANTIC WILL FAVOR THE NORTHWARD MOVEMENT...WHILE IN
THE LOWER LEVELS...FEEDER BAND STRUCTURES EXTEND THROUGHOUT THE
YUCATAN PENINSULA...SOUTHERN CENTRAL AMERICA...AND TO THE EXTREME
NORTHWEST COLOMBIA ON TUESDAY. THESE STRUCTURES ARE EXPECTED TO
CONTINUE TO EXTEND OVER PORTIONS OF THE NORTHERN CARIBBEAN AND THE
YUCATAN ON THURSDAY AND IN A LESSER DEGREE ON FRIDAY...DUE TO
HELENE MOVING FURTHER NORTH...AND INTO THE UNITED STATES. ON
WEDNESDAY...WESTERN CUBA CAN EXPECT MAXIMA OF 75-125MM WITH THE
POSSIBILITY OF HIGHER LOCALIZED AMOUNTS. THE NORTHERN REGION OF
THE YUCATAN CAN EXPECT MAXIMA OF 50-100MM AS DEEP CONVECTION
ASSOCIATED WITH HELENE CONTINUE THROUGHOUT THE DAY. THE CAYMAN
ISLANDS CAN EXPECT FEEDER BAND CONVECTION AND MAXIMA OF
35-70MM...SIMILARLY JAMAICA CAN EXPECT FEEDER BANDS TO FAVOR
MAXIMA OF 25-50MM. IN RELATION TO THE CYCLONIC CIRCULATION OF
HELENE...AND IN ADDITION TO THE PRESENCE OF THE MONSOON TROUGH
OVER CENTRAL AMERICA...THE GULF OF FONSECA REGION AND INTO WESTERN
NICARAGUA CAN EXPECT MAXIMA OF 50-100MM. ELSEWHERE IN THE REGION
EXPECT GENERALIZED MAXIMA UNDER 35MM. ON THURSDAY...EXPECT A SHARP
DECREASE IN PRECIPITATION AS THE FAST MOVING CYCLONE IS EXPECTED
FURTHER NORTH. WESTERN CUBA CAN EXPECT MAXIMA OF 20-40MM...WHILE
THE CAYMAN ISLANDS CAN EXPECT MAXIMA OF 15-30MM. REGIONS OF
CENTRAL AMERICA WILL SEE A DECREASE IN PRECIPITATION AS WELL AS
THE SYSTEM WILL BE FAR FROM THE REGION. HONDURAS/NICARAGUA/EL
SALVADOR CAN EXPECT MAXIMA OF 20-40MM. THE BAHAMAS CAN EXPECT AN
INCREASE IN AVAILABLE MOISTURE AND MAXIMA OF 15-20MM. BY
FRIDAY...EFFECTS FROM HELENE ARE NOT EXPECTED OVER THE REGION AND
MAXIMA OVER THE WESTERN CARIBBEAN ARE EXPECTED TO REMAIN BELOW
25MM. SIMILARLY IN CENTRAL AMERICA...MAXIMA ARE EXPECTED TO REMAIN
BELOW 45MM DUE TO THE PRESENCE OF THE MONSOON TROUGH AND FAVORABLE
ONSHORE FLOW IN THE PACIFIC BASIN.
TO THE WEST...THE NATIONAL HURRICANE CENTER IS WATCHING TROPICAL
STORM JOHN...LOCATED NEAR 16.2N AND 101.4W AT 15 UTC ON WEDNESDAY.
THE SYSTEM IS EXPECTED TO MEANDER ALONG THE WESTERN COAST OF
MEXICO...WITH HEAVY EFFECTS TO THE SOUTHERN PORTIONS OF GUERRERO
AND WEST OAXACA...AND EXTENDING TO MICHOACAN...COLIMA..AND
SOUTHERN JALISCO. THE AMOUNT OF PRECIPITABLE WATER IN THE REGION
WILL REMAIN HIGH AND CONDUCIVE FOR HEAVY PRECIPITATION WITH THE
EFFECTS OF THE WESTERLY ONSHORE FLOW INTO SOUTHWESTERN MEXICO. A
DECREASE IS EXPECTED BY FRIDAY AS THE SYSTEM IS EXPECTED TO
DISSIPATE FRIDAY EVENING. IN TERMS OF PRECIPITATION...ON WEDNESDAY
EXPECT MAXIMA OF 150-250MM IN GUERRERO AND PORTIONS OF WESTERN
OAXACA. FROM JALISCO...ALONG THE EJE VOLCANICO TRANSVERSAL..AND
INTO VERACRUZ EXPECT LESSER AMOUNTS BELOW 35MM. WESTERN
CHIAPAS/EAST OAXACA COULD EXPECT MAXIMA OF 20-45MM. ON
THURSDAY...THE HEAVIER PRECIPITATIONS ARE PROGRESSING TO THE
WEST...FROM COLIMA TO EXTREME WEST OAXACA...WHERE EXPECT MAXIMA OF
100-200MM. ELSEWHERE IS CENTRAL AND SOUTHERN MEXICO EXPECT MAXIMA
OF 20-45MM. FOR FRIDAY...THE SYSTEM COULD FAVOR MAXIMA OF 75-125MM
FROM GUERRERO TO OAXACA...AND MAXIMA OF 40-80MM FROM JALISCO TO
EXTREME WEST GUERRERO...AS THE SYSTEM DISSIPATES ON FRIDAY. OTHER
REGIONS IN CENTRAL MEXICO COULD SEE AMOUNTS OF 20-45MM.
DUE TO THE INTENSITY OF THE UPPER LEVEL RIDGING THAT IS RELATED TO
HURRICANE HELENE...AN UPPER JET OVER THE CENTRAL CARIBBEAN IS
DEEPENING AN UPPER TROUGH OVER THE CENTRAL CARIBBEAN AND INTO
CENTRAL VENEZUELA ON TUESDAY. IN ADDITION...THE PRESENCE OF A
UPPER RIDGE OVER THE EASTERN PACIFIC AND INTO PORTIONS OF CENTRAL
PERU AND BOLIVIA...IS ENHANCING THE VENTILATION FOR DEEP
CONVECTION OVER SOUTHERN COLOMBIA...AMAZONAS BRASIL...AND SOUTHERN
VENEZUELA. BY FRIDAY...THE UPPER LEVEL TROUGH OVER THE CARIBBEAN
SEA HAS RETROGRADED TO THE WESTERN CARIBBEAN...AND EXTENDS OVER
COSTA RICA AND PANAMA...INTERACTING WITH THE RIDGE TO THE
SOUTH...WHERE DIFFLUENCE AND ENHANCED DIVERGENCE IS EXPECTED OVER
NORTHWEST SOUTH AMERICA. IN ADDITION...BY FRIDAY..A LOW LEVEL
TROUGH ENTERS WEST BRASIL...SOUTH COLOMBIA...AND SOUTH VENEZUELA
FROM THE SOUTH...TRIGGERING THE CHANCE OF HEAVY PRECIPITATION IN
THE REGION. ON WEDNESDAY...GENERALIZED MAXIMA OF 20-35MM ARE
EXPECTED IN NORTH AND WEST COLOMBIA. TROUGHS IN THE LOWER LEVELS
OVER VENEZUELA AND INTO NORTH BRASIL WILL FAVOR ISOLATED
PRECIPITATION...WITH MAXIMA OF 15-25MM...AND HIGHER LOCALIZED
AMOUNTS ARE EXPECTED. ON THURSDAY...INCREASED ONSHORE FLOW IN
WESTERN COLOMBIA CAN FAVOR MAXIMA OF 20-45MM. INCREASED MOISTURE
IN VENEZUELA/EAST COLOMBIA...AND INTO NORTH BRASIL/NORTH
PERU/ECUADOR CAN EXPECT GENERALIZED MAXIMA OF 15-30MM. BY
FRIDAY...INCREASED MOISTURE CONVERGENCE IN THE LOWER
LEVELS...ASSOCIATED WITH THE PRESENCE OF A TROUGH...AND ENHANCED
BY THE UPPER DIVERGENT FEATURES...WILL FAVOR MAXIMA OF 25-50MM
FROM SOUTH COLOMBIA/VENEZUELA...TO NORTH PERU...AND INTO WEST
AMAZONAS-BRASIL. SIMILAR AMOUNTS ARE EXPECTED IN NORTH COLOMBIA
WITH THE INCREASE MOISTURE AND FLOW INTO THE NORTHERN REGION OF
COLOMBIA. IN THE WESTERN REGION OF COLOMBIA...INCREASED ONSHORE
FLOW WITH THE AVAILABLE MOISTURE IN THE REGION WILL FAVOR MAXIMA
OF 35-70MM. ELSEWHERE IN THE WESTERN REGION OF THE CONTINENT WILL
FAVOR GENERALIZED MAXIMA OF 15-35MM.
ELSEWHERE OVER THE CARIBBEAN BASIN...EXPECT DRIER
CONDITIONS...EXCEPT FOR THE LESSER ANTILLES OVER THE NEXT SEVERAL
DAYS. THE PRESENCE OF A TROPICAL WAVE IS EXPECTED TO BE
ACCOMPANIED BY AN INCREASE OF MOISTURE IN THE REGION. SEE BELOW
FOR DETAILS ON PRECIPITATION.
EASTERLY/TROPICAL WAVES INITIALIZED AT 12 UTC
TYPE SOF INIT 26/00 26/12 27/00 27/12 28/00 28/12 29/00 29/12
TW 17N 54W 56W 59W 62W 65W 68W 71W 74W 77W
A TROPICAL WAVE IS INITIALIZED AT 54W AND TO THE SOUTH OF 17N. ON
WEDNESDAY...THE TROPICAL WAVE IS EXPECTED TO PROPAGATE CLOSE TO
NORTH GUYANA...WITH TRACE AMOUNTS OF PRECIPITATION EXPECTED. ON
THURSDAY...THE WAVE IS EXPECTED OVER THE LESSER ANTILLES AND
EXTREME NORTHEAST VENEZUELA. ENHANCED BY AN UPPER LEVEL TROUGH IN
THE CARIBBEAN BASIN...EXPECT MAXIMA OF 15-30MM IN THE LESSER
ANTILLES...TRINIDAD...AND NORTH VENEZUELA. BY FRIDAY...THE
TROPICAL WAVE IS EXPECTED BETWEEN HISPANIOLA AND PUERTO RICO...AND
EXTENDS INTO NORTHWEST VENEZUELA. MAXIMA OF 15-25MM ARE EXPECTED
IN HISPANIOLA AND PUERTO RICO...WHILE MAXIMA OF 20-35MM ARE
EXPECTED IN NORTHWEST VENEZUELA.
ACOSTA...(WPC)
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