TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
325 PM EDT THU SEP 26 2024
FORECAST BULLETIN 26 SEP 2024 AT 1830 UTC:
THE NATIONAL HURRICANE CENTER IS MONITORING TROPICAL CYCLONE
HELENE LOCATED NEAR 25.5N AND 85.5W ON THURSDAY.THE UPPER-LEVEL
TROUGH OVER THE NORTHERN GULF OF MEXICO...ALONG WITH THE RIDGE TO
THE NORTHEAST EXTENDING OVER THE BAHAMAS AND INTO THE NORTHERN
ATLANTIC...WILL SUPPORT A NORTHWARD MOVEMENT OF THE SYSTEM. IN THE
LOWER LEVELS...FEEDER BAND STRUCTURES ARE EXPECTED TO PERSIST
ACROSS PORTIONS OF THE NORTHERN CARIBBEAN ON THURSDAY. AS
HURRICANE HELENE CONTINUES MOVING NORTHWARD...THE FEEDER BAND
CONVECTION ASSOCIATED TO THIS SYSTEM WILL FAVOR A MAXIMA OF
20-35MM OVER WESTERN CUBA AND 15-25MM OVER YUCATAN PENINSULA ON
THURSDAY AND FRIDAY. THE IMPACT OF THIS SYSTEM WILL DIMINISH AS
HELENE CONTINUES TO MOVE FURTHER NORTH INTO THE UNITED STATES.
THE NATIONAL HURRICANE CENTER IS ALSO MONITORING THE TROPICAL
STORM JOHN...LOCATED NEAR 17.5N AND 102.7W AT 15 UTC ON THURSDAY.
THE TROPICAL STORM IS EXPECTED TO CONTINUE MOVING ALONG THE
WESTERN COAST OF MEXICO. FORECASTS INDICATE THAT HIGH LEVELS OF
MOISTURE WILL PERSIST...DUE TO ONSHORE FLOW LEADING TO SIGNIFICANT
PRECIPITATION FROM THURSDAY INTO FRIDAY. BY SATURDAY A DECREASE IN
PRECIPITATION IS EXPECTED. ON THURSDAY..RAINFALL MAXIMA ARE
EXPECTED TO REACH A MAXIMA OF 75-125MM IN COLIMA..GUERRERO AND
MICHOACAN. IN PORTIONS OF WESTERN OAXACA A MAXIMA OF 20-35MM. IN
JALISCO...ALONG THE EJE VOLCĂNICO TRANSVERSAL...EXTENDING INTO
VERACRUZ...A MAXIMA OF 15-25MM IS EXPECTED.
LOOKING AHEAD TO FRIDAY...AS THE SYSTEM BEGINS TO
DISSIPATE...COLIMA...GUERRERO...MICHOACAN WILL EXPERIENCE MAXIMA
OF 75-125MM. IN JALISCO AND CENTRAL MEXICO A MAXIMA OF 20-40MM IS
EXPECTED. OVER THE EJE VOLCANICO TRANSVERSAL AND SOUTH
VERACRUZ...WESTERN CHIAPAS AND EAST OAXACA...EXPECT A RAINFALL
MAXIMA OF 15-25MM. BY SATURDAY FROM JALISCO TO NORTHERN GUERRERO
MAXIMA OF 15-25MM AND FROM SOUTHERN GUERRERO TO OAXACA MAXIMA OF
20-45MM...IN NAYARIT MAXIMA OF 20-35MM...OVER PUEBLA AND VERACRUZ
THEY MAY EXPERIENCE MAXIMA OF 25-50MM.
PLEASE REVIEW THE MOST RECENT FORECAST FOR THE ACTIVE TROPICAL
CYCLONE ISSUED BY THE NATIONAL HURRICANE CENTER ON THEIR WEBSITE:
WWW.HURRICANES.GOV
IN THE UPPER LEVELS THE PRESENCE OF A RIDGE OVER THE EASTERN
PACIFIC EXTENDING INTO PORTIONS OF CENTRAL PERU AND BOLIVIA IS
ENHANCING VENTILATION FOR DEEP CONVECTION OVER SOUTHERN
COLOMBIA...AMAZONAS BRAZIL AND SOUTHERN VENEZUELA WILL PERSIST IN
THE NEXT FORECAST CYCLE.
IN ADDITION...BY FRIDAY...THE UPPER-LEVEL TROUGH OVER THE
CARIBBEAN SEA IS EXPECTED TO RETROGRADE TO THE WESTERN
CARIBBEAN..EXTENDING OVER COSTA RICA AND PANAMA..WHERE IT WILL
INTERACT WITH THE RIDGE TO THE SOUTH..RESULTING IN INCREASED
DIFFLUENCE AND ENHANCED DIVERGENCE OVER NORTHWEST SOUTH AMERICA.
IN ADDITION THE INCREASE ON THE MOISTURE LEVELS DUE TO THE ONSHORE
FLOW FAVORED BY THE LOW-LEVEL JET...WILL FAVOR THE CHANCE OF HEAVY
PRECIPITATION. THIS LEADS TO A MAXIMA OF 20-35MM ON THURSDAY OVER
COLOMBIA ON THURSDAY. AN INCREASE WILL BE OBSERVED IN THE NEXT FEW
DAYS.. WITH MAXIMA OF 25-50MM IN WESTERN COLOMBIA AND 20-35MM FROM
CENTRAL COLOMBIA INTO ECUADOR ON FRIDAY. BY SATURDAY MAXIMA OF
40-80MM IN WESTERN COLOMBIA AND 25-50MM IN NORTHERN COLOMBIA AND
WESTERN VENEZUELA IS EXPECTED. ADDITIONAL MAXIMA OF 20-35MM FROM
CENTRAL COLOMBIA INTO ECUADOR WILL PERSIST ON SATURDAY.
EASTERLY/TROPICAL WAVES INITIALIZED AT 12 UTC
TYPE SOF INIT 27/00 27/12 28/00 28/12 29/00 29/12 30/00 30/12
TW 18N 61W 63W 66W 69W 72W 75W 78W 81W 84W
AN INCREASE IN MOISTURE IS EXPECTED FROM THURSDAY INTO SATURDAY AS
A TROPICAL WAVE ENHANCED BY AN UPPER-LEVEL TROUGH IN THE CARIBBEAN
BASIN MOVES OVER THE LESSER ANTILLES AND EXTREME NORTHEASTERN
VENEZUELA. BY THURSDAY...RAINFALL MAXIMA OF 25-50MM ARE EXPECTED
IN THE LESSER ANTILLES...TRINIDAD...IN VENEZUELA AND NORTHERN
BRASIL EXPECT MAXIMA OF 20-40MM. ANOTHER MAXIMA OF 20-35MM IN
PUERTO RICO AND EAST OF DOMINICAN REPUBLIC ON THURSDAY. ON FRIDAY
IN THE LESSER ANTILLES...IN VENEZUELA AND NORTHERN BRASIL WILL
OBSERVED A DECREASE WITH MAXIMA OF 15-25MM. HOWEVER...PUERTO RICO
AND DOMINICAN REPUBLIC WILL EXPERIENCE AN INCREASE WITH MAXIMA OF
20-35MM. AS THE TROPICAL WAVE CONTINUES PROPAGATING OVER THE
WESTERN CARIBBEAN...BY SATURDAY RAINFALL MAXIMA OF 15-25MM OVER
PUERTO RICO...DOMINICAN REPUBLIC AND EAST OF CUBA IS
EXPECTED...AND JAMAICA CAN EXPECT A MAXIMA OF 20-35MM.
ACOSTA...(WPC)
LEDESMA...(WPC)
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