260
FXCA20 KWBC 241838
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
237 PM EDT WED SEP 24 2025
FORECAST BULLETIN 24 SEPTEMBER 2025 AT 1800 UTC:
SYNOPSIS:
SIGNIFICANT PRECIPITATION IS EXPECTED TO OCCUR TODAY AND TOMORROW
IN MUCH OF THE CARIBBEAN, PARTICULARLY PUERTO RICO, THE VIRGIN
ISLANDS, AND THE DOMINICAN REPUBLIC, DUE TO THE PASSAGE OF A
TROPICAL WAVE (AL94) WITH INSTANCES OF FLASH AND URBAN FLOODING
EXPECTED. ACCORDING TO THE LATEST NHC TROPICAL WEATHER OUTLOOK,
AFTER PASSING THROUGH THE DOMINICAN REPUBLIC, THE WAVE IS EXPECTED
TO FORM A CLOSED CIRCULATION, SLOW DOWN, AND TURN NORTHWESTWARD
WHEN IT REACHES THE SOUTHWEST ATLANTIC LATE THIS WEEK. IN
NORTHWEST MEXICO, REMNANT MOISTURE ASSOCIATED WITH HURRICANE NARDA
IS EXPECTED TO LINGER IN THE AREA, WITH HEAVY PRECIPITATION
EXPECTED TODAY AND THURSDAY. MUCH OF CENTRAL AMERICA WILL BE
MOSTLY DRY WITH THE ADVECTION OF DRY AND STABLE AIR, WITH THE
EXCEPTION OF LOCALIZED AND SEASONABLE LIGHT CONVECTION. IN
TROPICAL SOUTH AMERICA, MOIST AIR WILL RETURN, AND SEASONABLE
CONVECTION IS EXPECTED TO RESUME BEGINNING TODAY.
THE BAHAMAS AND THE CARIBBEAN:
A TROPICAL WAVE, CURRENTLY KNOWN AS AL94 AND LOCATED AT 66W, IS
EXPECTED TO BRING MAJOR IMPACTS TO THE ISLAND OF HISPANIOLA,
PUERTO RICO, THE VIRGIN ISLANDS, AND THE LEEWARD ISLANDS TODAY AND
THURSDAY. SIGNIFICANT MOISTURE WILL BE ADVECTED FROM THE SOUTH OF
THE VIRGIN ISLANDS AND PUERTO RICO, WITH PWAT VALUES OVER 64MM.
CLEARING EARLIER THIS MORNING PROVIDED SIGNIFICANT SURFACE HEATING
AND INSTABILITY WHICH WILL BE HIGHLY CONDUCIVE FOR CONVECTION TO
OCCUR LATER IN THE AFTERNOON INTO THE EVENING. THE MOST
SIGNIFICANT IMPACTS ARE EXPECTED TO OCCUR IN THE INTERIOR,
SOUTHERN, AND EASTERN PUERTO RICO AND MOST OF THE VIRGIN ISLANDS,
WITH MAXIMUM PRECIPITATION OF 75-150MM EXPECTED TODAY, WITH
LOCALLY HIGHER AMOUNTS POSSIBLE. URBAN AND FLASH FLOODING ARE
LIKELY TO OCCUR THIS AFTERNOON AND EVENING WITH THE HIGH AMOUNTS
OF PRECIPITATION EXPECTED IN A SHORT PERIOD OF TIME. IN THE
NORTHERN LEEWARD ISLANDS, HEAVY PRECIPITATION OF UP TO 25-50MM IS
ALSO POSSIBLE WITH THE PASSAGE OF THE TROPICAL WAVE.
OVERNIGHT TONIGHT AND THURSDAY, THE WAVE IS EXPECTED TO MAKE ITS
WAY THROUGH THE EAST OF THE DOMINICAN REPUBLIC, TRAVELING AT A
WEST-NORTHWEST TRAJECTORY. OROGRAPHIC EFFECTS WILL AID IN THE
ENHANCING OF CONVECTION THAT OCCURS, AND HEAVY PRECIPITATION IS
EXPECTED TO BEGIN EARLY IN THE MORNING THURSDAY INTO THE EVENING.
PRECIPITATION AMOUNTS OF 25-50MM ARE EXPECTED TODAY, AND 30-60MM
ARE EXPECTED TOMORROW.
AFTER PASSING THROUGH THE DOMINICAN REPUBLIC, THE WAVE IS FORECAST
TO DEVELOP INTO A CLOSED CIRCULATION, WITH THE NATIONAL HURRICANE
CENTER CONTINUING TO MONITOR ITS DEVELOPMENT. THERE IS CURRENTLY
AN 80% OF TROPICAL CYCLONE DEVELOPMENT WITH THIS WAVE IN THE NEXT
SEVEN DAYS, MOST LIKELY OCCURRING SOON AFTER ITS DEPARTURE FROM
THE DOMINICAN REPUBLIC. AT THIS POINT, INTERESTS IN THE BAHAMAS
AND TURKS AND CAICOS SHOULD CONTINUE MONITORING THE LATEST
FORECASTS IN ASSOCIATION WITH THIS WAVE TOWARDS THE WEEKEND. HEAVY
PRECIPITATION IS EXPECTED BEGINNING ON FRIDAY IN THE TURKS AND
CAICOS ISLANDS, BEFORE MOVING INTO THE BAHAMAS ON SATURDAY, WITH
MAXIMUM PRECIPITATION OF 30-60MM EXPECTED.
MEXICO AND CENTRAL AMERICA:
REMNANT MOISTURE ASSOCIATED WITH HURRICANE NARDA IS EXPECTED TO
ADVECT FROM THE SOUTH INTO THE GULF OF CALIFORNIA, WITH EFFECTS
TAKING PLACE IN NORTHWEST MEXICO INCLUDING SONORA, CHIHUAHUA, AND
SINALOA THROUGH THE NEXT THREE DAYS. STRONG LOW-LEVEL FLOW IS
EXPECTED TO ACCOMPANY THE MOISTURE, ALONG WITH LOW-LEVEL
CONVERGENCE OF WIND AND MOISTURE, AND UPPER-LEVEL DIVERGENCE AT
THE EASTERN PERIPHERY OF AN UPPER-LEVEL RIDGE IN NORTHWEST MEXICO.
THIS WILL BE CONDUCIVE TO DAILY HEAVY PRECIPITATION THROUGHOUT THE
FORECAST PERIOD, WITH PRECIPITATION VALUES PEAKING AT AROUND
30-60MM TODAY AND THURSDAY.
FURTHER SOUTH, IN COLIMA, MICHOACAN, GUERRERO, AND PARTS OF
JALISCO, THE AFOREMENTIONED MOISTURE IS ALSO EXPECTED TO PROVIDE
PRECIPITATION TODAY AND THURSDAY. THE LOWER LEVEL FLOW WILL BE
SLIGHTLY WEAKER, BUT IS STILL EXPECTED TO FLOW PERPENDICULARLY
ONSHORE AND BE LIFTED OROGRAPHICALLY. PRECIPITATION TOTALS OF
25-50MM ARE EXPECTED TODAY, AND ARE ANTICIPATED TO DIMINISH
GRADUALLY OVER THE NEXT FEW DAYS, AS NARDA MOVES FURTHER OFFSHORE
AND LOSES ITS INFLUENCE IN THE REGION.
A STRONG TRADE WIND INVERSION ALONG WITH STABLE AND DRY AIR WILL
MOVE THROUGH HONDURAS AND NICARAGUA AND NEARBY AREAS TODAY AND
THURSDAY. THIS IS EXPECTED TO SUBSIDE BEGINNING THIS WEEKEND, WHEN
SEASONABLE PRECIPITATION IS EXPECTED TO RETURN. UNTIL THEN, ANY
PRECIPITATION WILL BE VERY LIGHT AND LOCALIZED OVER THE NEXT FEW
DAYS.
TROPICAL SOUTH AMERICA:
IN THE WEST COAST OF COLOMBIA, MOISTURE FROM THE INFLUENCE OF THE
PANAMANIAN LOW IS EXPECTED TO MOVE IN PERPENDICULAR TO THE COAST.
WITH SUPPORT OF A SUBTLE MID-LEVEL SHORTWAVE TROUGH, POTENTIALLY
HEAVY PRECIPITATION COULD BE POSSIBLE, ESPECIALLY ON FRIDAY AND
SATURDAY WITH TOTALS OF UP TO 25-50MM POSSIBLE. CONDITIONS IN
TROPICAL SOUTH AMERICA WILL CONTINUE TO CONSIST OF SEASONABLE AND
DAILY CONVECTION, PARTICULARLY IN THE CENTRAL EQUATORIAL REGIONS
INCLUDING COLOMBIA, WESTERN ECUADOR, PERU, AND VENEZUELA. MOIST
AIR WILL CONTINUE TO BE ADVECTED INTO THIS REGION AND INTERACT
WITH THE LOCAL TOPOGRAPHY, WHICH WILL ALLOW FOR DIURNAL AND
LOCALIZED CONVECTION THROUGHOUT THE NEXT FEW DAYS.
POSITIONS OF TROPICAL/EASTERLY WAVES INITIALIZED AT 12 UTC
TYPE SOF INIT 25/00 25/12 26/00 26/12 27/00 27/12 28/00 28/12
TW 23N 54W 56W 57W 58W 59W 60W 61W 62W 64W
TW 21N 67W 69W 71W 73W 74W 74W 74W 74W 75W
TW 16N 95W 98W 100W 102W 104W ---------------------
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