961
FXCA20 KWBC 201913
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
313 PM EDT TUE OCT 20 2026
FORECAST BULLETIN 20 OCTOBER 2026 AT 1800 UTC:
THE BAHAMAS AND CARIBBEAN:
A FRONTAL BOUNDARY IN THE ATLANTIC EXTENDING INTO THE GULF WILL
ENHANCE LOW-LEVEL MOISTURE CONVERGENCE OVER THE BAHAMAS AND CUBA
THROUGH WEDNESDAY. THIS WILL BRING RAINFALL ACCUMULATIONS OF
15-30MM OVER CUBA AND THE BAHAMAS. ADDITIONALLY, A MID- TO
UPPER-LEVEL TROUGH WITH AN AXIS OVER CUBA AND THE BAHAMAS WILL
INTRODUCE INSTABILITY, TRIGGERING THUNDERSTORMS IN THE REGION. A
MARGINAL RISK OF SEVERE WEATHER EXISTS FROM TODAY THROUGH
WEDNESDAY MORNING. UPPER-LEVEL DIVERGENCE ASSOCIATED WITH THIS
TROUGH IS ALSO EXPECTED TO BRING RAINFALL OVER HISPANIOLA THROUGH
WEDNESDAY, WITH ACCUMULATIONS RANGING FROM 15-25MM. LOW-LEVEL
CONVERGENCE WILL PERSIST OVER THE BAHAMAS FROM WEDNESDAY THROUGH
THURSDAY; HOWEVER, LOWER PWAT WILL RESULT IN LIGHTER
ACCUMULATIONS, THOUGH THUNDERSTORMS REMAIN LIKELY DUE TO THE
UPPER-LEVEL TROUGH SUPPORTING UPPER-LEVEL DIVERGENCE IN THE
REGION. ELSEWHERE IN THE CARIBBEAN, RELATIVELY DRY CONDITIONS WILL
PREVAIL TODAY DUE TO LOW PWAT, THOUGH DIURNAL HEATING AND LOCAL
EFFECTS WILL TRIGGER LIGHT RAINFALL. A MOISTURE PLUME WILL BRING
LIGHT RAIN OVER THE WINDWARD ISLANDS, WITH CONVECTION REMAINING
SHALLOW UNDER MID-LEVEL RIDGING AND ZONAL WINDS ALOFT. CONVECTIVE
ACTIVITY AND RAINFALL WILL INCREASE FROM THURSDAY THROUGH FRIDAY
AS AN UPPER-LEVEL TROUGH DEEPENS OVER THE CARIBBEAN. SOUTHERLY
LOW-LEVEL WINDS WILL ADVECT DEEP MOISTURE, COMBINING WITH
UPPER-LEVEL DIFFLUENCE OVER HISPANIOLA AND PUERTO RICO TO SUSTAIN
A MORE ACTIVE WEATHER PATTERN. THE HEAVIEST PRECIPITATION IS
EXPECTED OVER HISPANIOLA, DRIVEN BY A SURFACE LOW IN THE CARIBBEAN
THAT ENHANCES LOW-LEVEL MOISTURE CONVERGENCE IN THE AREA.
MEXICO AND CENTRAL AMERICA:
A COLD FRONT EXTENDING FROM THE ATLANTIC INTO THE GULF AND MEXICO
WILL INCREASE LOW-LEVEL CONVERGENCE ALONG THE EASTERN COAST OF
MEXICO AND PROMOTE DEEP MOISTURE ADVECTION, BRINGING HEAVY
PRECIPITATION OVER THE VERACRUZ REGION AND THE YUCATAN PENINSULA
THROUGH WEDNESDAY. TOTALS ARE ANTICIPATED TO RANGE BETWEEN
20-45MM. ADDITIONAL LOCALIZED HEAVIER PRECIPITATION IS LIKELY DUE
TO STRONG LOW-LEVEL WINDS ASSOCIATED WITH THE TEHUANTEPECER
LOW-LEVEL JET AND OROGRAPHIC ENHANCEMENT. LOW-LEVEL WINDS WILL
CONTINUE CONVERGING ALONG THE COAST FROM WEDNESDAY THROUGH
THURSDAY, DUE TO THE PRESENCE OF AN INDUCED LOW-LEVEL TROUGH,
ADVECTING MOISTURE TO SUSTAIN PRECIPITATION OVER EASTERN MEXICO.
ADDITIONAL 20-45MM ARE FORECASTED FOR VERACRUZ FROM WEDNESDAY
THROUGH THURSDAY.
ALONG THE PACIFIC COAST OF NORTHERN CENTRAL AMERICA, A
LOW-PRESSURE SYSTEM WILL DRAW MOISTURE INTO THE REGION, SUPPORTING
RAINFALL THROUGH WEDNESDAY ACROSS THE WESTERN COAST OF GUATEMALA
AND EL SALVADOR. RAINFALL ACCUMULATIONS WILL BE AROUND 20-35MM IN
THAT REGION. FURTHER SOUTH, HEAVY PRECIPITATION IS EXPECTED OVER
COSTA RICA AND PANAMA DUE TO THE MONSOON TROUGH, DEEP MOISTURE,
AND THE DEVELOPING PANAMANIAN LOW ENHANCING LOW-LEVEL MOISTURE
CONVERGENCE. TODAY THROUGH WEDNESDAY TOTAL PRECIPITATION IS
EXPECTED TO REACH 25-50MM. SIMILAR CONDITIONS WILL PERSIST
THROUGHOUT THE FORECAST PERIOD, WITH THE HEAVIEST RAINFALL
OCCURRING TODAY THROUGH THURSDAY WHEN CYCLONIC FLOW AND
INSTABILITY PEAK.
TROPICAL SOUTH AMERICA:
HEAVY RAINFALL IS EXPECTED THROUGH WEDNESDAY ALONG THE PACIFIC
COAST OF COLOMBIA AND ECUADOR AS LOW-LEVEL WESTERLY FLOW ADVECTS
DEEP MOISTURE FROM THE PACIFIC. ADDITIONAL RAINFALL WILL AFFECT
THE REGION FROM WEDNESDAY THROUGH THURSDAY AS THESE WESTERLIES
CONVERGE, FURTHER PROMOTING INSTABILITY. THUNDERSTORMS ARE ALSO
EXPECTED TODAY IN THE CHOCO REGION IN COLOMBIA DUE TO CYCLONIC
FLOW ASSOCIATED WITH THE PANAMANIAN LOW ENHANCING LOW-LEVEL
MOISTURE CONVERGENCE. DEEP MOISTURE, A LOW-LEVEL TROUGH, AND
UPPER-LEVEL DIFFLUENCE WILL CREATE FAVORABLE CONDITIONS FOR
CONVECTIVE ACTIVITY IN THE COLOMBIA CARIBBEAN AND LAKE MARACAIBO
REGION VENEZUELA FROM WEDNESDAY TO THURSDAY. OVER THE WESTERN AND
NORTHWESTERN AMAZON, MOISTURE ADVECTION WILL SUSTAIN HEAVY
RAINFALL THROUGHOUT THE FORECAST PERIOD. CONVERSELY, THE EASTERN
PORTION OF THE CONTINENT WILL REMAIN DRY UNDER LOW PWAT VALUES.
RIVERA-TORRES...(WPC)
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