776
FXCA20 KWBC 291915
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
315 PM EDT MON SEP 29 2025
NOTE: UPDATED DATE
FORECAST BULLETIN 29 SEPTEMBER 2025 AT 1920 UTC:
THE BAHAMAS AND CARIBBEAN:
HEAVY RAINFALL CONTINUES OVER NORTHERN BAHAMAS, AS TROPICAL STORM
IMELDA CONTINUES TO MOVE NORTHWARD AND AWAY FROM THE REGION.
ADDITIONAL 25-50MM OF RAIN CAN BE EXPECTED TODAY INTO TUESDAY, AND
CONDITIONS SHOULD IMPROVE FOR THE FORECAST PERIOD. TURKS AND
CAICOS, SOUTHEASTERN CUBA AND JAMAICA WILL RECEIVE PRECIPITATION
DUE TO THE ONSHORE FLOW AND MOISTURE ADVECTION FROM THE HURRICANE
HUMBERTO, PARTICULARLY FROM TODAY TO TUESDAY. CUBA SHOULD EXPECT
MORE THUNDERSTORMS AND PERIODS OF HEAVY RAINFALL WITH LOW-LEVEL
CONVERGENCE HAPPENING MOSTLY AT NIGHTTIME AND EARLY MORNING, AND A
MID-LEVEL TROUGH GIVING ADDITIONAL SUPPORT FOR CONVECTIVE
ACTIVITY. ONSHORE MOISTURE ADVECTION WILL CONTINUE FROM TUESDAY TO
THURSDAY FOR THAT REGION. FROM WEDNESDAY TO THURSDAY THUNDERSTORMS
ARE EXPECTED OVER HISPANIOLA, AS LOW-LEVEL TROUGH MOVES INTO THE
AREA AND A SHORT-LIVED WEAK UPPER LEVEL TROUGH IS OVER THE REGION.
ALTHOUGH THE LOW-LEVEL TROUGH LACKS MOISTURE AND CONVECTIVE
ACTIVITY IT CAN BRING ENOUGH INSTABILITY TO THE AREA, AND IN
COMBINATION WITH DIURNAL HEATING AND OROGRAPHY THUNDERSTORMS COULD
GENERATE CONVECTIVE ACTIVITY. MEANWHILE, A COLD FRONT MAY BRING
RAINFALL TO PORTIONS OF THE BAHAMAS ON THURSDAY. FOR THE REST OF
THE CARIBBEAN, CONDITIONS WILL REMAIN RELATIVELY QUIET FOR THE
NEXT THREE DAYS UNDER THE INFLUENCE OF DRY AIR. HOWEVER, LOCALIZED
SEASONABLE PRECIPITATION CAN BE EXPECTED DUE TO DIURNAL AND LOCAL
EFFECTS.
MEXICO AND CENTRAL AMERICA:
OVER MEXICO PRECIPITATION IS EXPECTED TODAY AND TUESDAY OVER
PORTIONS OF SIERRA MADRE OCCIDENTAL WITH MAXIMA OVER SINALOA AND
NAYARIT, AS A LOW-LEVEL TROUGH IN THE PACIFIC COAST WILL INTRODUCE
MOISTURE IN THE REGION, SUPPORTED BY A MID-LEVEL SHORTWAVE TROUGH
AND ENHANCED DIVERGENCE IN THE BASE OF A TROUGH THAT MOVES
EASTERLY AND THE PERIPHERY OF AN UPPER LEVEL TROUGH THAT STARTS TO
DEVELOP OVER WESTERN MEXICO BY TUESDAY MORNING. FROM TUESDAY TO
THURSDAY PRECIPITATION IS EXPECTED AGAIN OVER THE WESTERN REGION
OF MEXICO. ALTHOUGH ACCUMULATION IS EXPECTED TO BE LESS COMPARED
TO THE PREVIOUS DAY AS THE LOW-LEVEL TOUGH MOVES AWAY. HOWEVER
THERE IS STILL MOISTURE ALONG THE PACIFIC COAST, AND SOME SUPPORT
FROM MID-LEVEL SHORTWAVE TROUGHS AND ENHANCED DIVERGENCE ALONG THE
PERIPHERY OF AN UPPER LEVEL HIGH LOCATED OVER WESTERN MEXICO.
FROM TODAY TO TUESDAY RAINFALL IS EXPECTED OVER SOUTHWESTERN
MEXICO, WESTERN GUATEMALA AND EL SALVADOR WITH AN UPPER-LEVEL
TROUGH FROM SOUTHERN MEXICO INTO EL SALVADOR PROPAGATING WEST, AND
LOW-LEVEL MOISTURE CONVERGING IN THE REGION. AN AREA OF INTEREST
IS EL SALVADOR AND, AS THE MODEL SUGGESTS THE PRESENCE OF A
MID-LEVEL TROUGH AND ENHANCED MID-LEVEL VORTICITY IN THE REGION.
AS PRECIPITATION MAXIMA IS EXPECTED AGAIN OVER EL SALVADOR AND
WESTERN HONDURAS AND NICARAGUA FROM TUESDAY TO THURSDAY, WITH A
SHEAR LINE FROM THE CARIBBEAN INTO HONDURAS ENHANCING LOW LEVEL
CONVERGENCE AND WITH ENHANCED UPPER-LEVEL DIVERGENCE IN THE REGION.
AN INCREASE IN RAINFALL IS EXPECTED OVER VERACRUZ FROM WEDNESDAY
AND THURSDAY, AS A LOW IN THE GULF OF CAMPECHE MOVES WEST AND
APPROACHES THE REGION. ALTHOUGH THERE IS STILL SOME UNCERTAINTY
BETWEEN THE MODELS, MAXIMUM RAINFALL BETWEEN 20-45MM IS EXPECTED.
IN COSTA RICA AND PANAMA, CONDITIONS ARE EXPECTED TO REMAIN
SIMILAR THE NEXT THREE DAYS, WITH THE PRESENCE OF THE MONSOON
TROUGH AND A LOW ENHANCING CIRCULATION IN THE REGION THAT WILL
FAVOR MOIST ONSHORE FLOW, WITH FAVORABLE CONDITIONS AT MID- TO
UPPER-LEVELS ACCUMULATIONS OF 20-35MM ARE POSSIBLE, WITH LOCALIZED
HIGHER VALUES.
SOUTH AMERICA:
IN SOUTH AMERICA PRECIPITATION IS EXPECTED TO BE MOSTLY DUE TO
DIURNAL HEATING AND LOCAL EFFECTS. FOR THE NEXT THREE DAYS THE
PACIFIC REGION OF COLOMBIA WILL RECEIVE PRECIPITATION WITH
MOISTURE COMING FROM THE PACIFIC. IN THE ANDES REGION OF COLOMBIA
ENHANCEMENT OF UPPER-LEVEL DIVERGENCE AND LOW-LEVEL MOISTURE
CONVERGENCE, AND OROGRAPHIC EFFECTS WILL ENHANCE CONVECTIVE
ACTIVITY OVER THE REGION, PARTICULARLY FROM TODAY TO TUESDAY. FROM
TUESDAY TO WEDNESDAY THE PANAMANIAN LOW SHOULD BRING SOME MOISTURE
INTO THE CARIBBEAN REGION OF COLOMBIA. THAT SAME DAY, INSTABILITY
WILL ENHANCE PRECIPITATION OVER COLOMBIA, AND VENEZUELA AROUND THE
MARACAIBO LAKE REGION WITH THE PRESENCE OF A LOW-LEVEL TROUGH AND
A MID-LEVEL TROUGH WITH AN AXIS OVER LA GUAJIRA PENINSULA IN
COLOMBIA.
TYPE SOF INIT 30/00 30/12 01/00 01/12 02/00 02/12 03/00
TW 11N 35W 39W 42W 45W 47W 48W 49W 50W
TW 15N 44W47W 50W 52W 54W 56W ----------
TW 13N 113W 114W 115W 116W 116W EXIT EXIT-----
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