593
FXCA20 KWBC 171920
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
320 PM EDT THU SEP 17 2026
FORECAST BULLETIN 16 SEPTEMBER 2026 AT 1900 UTC:
THE BAHAMAS AND CARIBBEAN:
IN THE CARIBBEAN, PRECIPITATION IS ANTICIPATED FOR TODAY OVER
PORTIONS OF PUERTO RICO AND THE DOMINICAN REPUBLIC DUE TO THE
PRESENCE OF A TROPICAL WAVE INCREASING THE PRECIPITABLE WATER
AVAILABILITY AND LOW-LEVEL MOISTURE CONVERGENCE. ACCUMULATIONS ARE
EXPECTED TO BE AROUND 15-35 MM OVER THE DOMINICAN REPUBLIC AND
AROUND 15-20 MM FOR PUERTO RICO. LIGHT RAINFALL IS ALSO EXPECTED
TODAY OVER THE BAHAMAS DUE TO THE PRESENCE OF A LOW-LEVEL TROUGH
ENHANCING LOW-LEVEL MOISTURE CONVERGENCE. TOTALS WILL RANGE FROM
15-25 MM IN THIS REGION TODAY THROUGH FRIDAY. PRECIPITATION WILL
CONTINUE OVER HISPANIOLA FROM FRIDAY THROUGH SATURDAY AS THE
TROPICAL WAVE CONTINUES PROPAGATING WESTWARD OVER THE CARIBBEAN,
KEEPING HIGH VALUES OF PWAT IN THE REGION, WITH DEEP MOISTURE
BEING ADVECTED BY SOUTHEASTERLY FLOW. THUNDERSTORMS ARE ALSO
EXPECTED OVER HISPANIOLA EARLY ON SATURDAY DUE TO UPPER-LEVEL
DIFFLUENCE ALONG THE PERIPHERY OF AN UPPER-LEVEL RIDGE OVER THE
CARIBBEAN. RAINFALL AND CONVECTIVE ACTIVITY ARE ALSO EXPECTED FROM
FRIDAY THROUGH SUNDAY OVER CUBA AND THE BAHAMAS, AS LOW-LEVEL
TROUGHING PERSISTS AND UPPER-LEVEL DIVERGENCE INCREASES WITH AN
UPPER-LEVEL TROUGH, REFLECTED IN MID-LEVELS, OVER THE SOUTHEASTERN
U.S. DRIER CONDITIONS ARE EXPECTED OVER THE EASTERN ANTILLES
TOWARDS THE END OF THE FORECAST PERIOD AS PWAT DECREASES, BUT
LIGHT RAINFALL DUE TO DIURNAL HEATING AND LOCAL EFFECTS IS LIKELY.
MEXICO AND CENTRAL AMERICA:
THE PRESENCE OF A LOW-LEVEL TROUGH OVER THE GULF WILL PROMOTE THE
ADVECTION OF DEEP MOISTURE INTO THE EASTERN REGION OF MEXICO,
INCREASING RAINFALL ACTIVITY. THIS IS FORECASTED TO RESULT IN
MODERATE ACCUMULATIONS RANGING FROM 20-40 MM. RAINFALL IS ALSO
EXPECTED TODAY THROUGH FRIDAY OVER NORTHWESTERN MEXICO, AS
UPPER-LEVEL DIVERGENCE INCREASES WITH AN UPPER-LEVEL TROUGH
PROPAGATING WESTWARD AND AN UPPER-LEVEL RIDGE CONTINUES OVER
NORTHERN MEXICO. TOTALS ARE ANTICIPATED TO RANGE FROM 20-40 MM.
PRECIPITATION IS ALSO ANTICIPATED TODAY OVER SOUTHWESTERN MEXICO,
WHERE DEEP MOISTURE FROM THE PACIFIC IS BEING ADVECTED INTO
MEXICO, SUPPORTED BY THE PRESENCE OF SHORTWAVE MID-LEVEL TROUGHS
AND AN UPPER-LEVEL TROUGH OVER THE PACIFIC INCREASING UPPER-LEVEL
DIVERGENCE. PRECIPITATION IS EXPECTED TO CONTINUE FROM FRIDAY
THROUGH SATURDAY OVER SOUTHERN MEXICO AND NORTHERN CENTRAL
AMERICA, WITH A LOW-LEVEL TROUGH PROMOTING LOW-LEVEL CONVERGENCE
AND UPPER-LEVEL DIVERGENCE DUE TO THE PRESENCE OF AN UPPER-LEVEL
TROUGH OVER THE YUCATÃN PENINSULA. ACCUMULATIONS, HOWEVER, ARE
EXPECTED TO REMAIN ON THE LOWER END BECAUSE OF THE RELATIVELY LOW
PWAT VALUES IN THE AREA. AN INCREASE IN PRECIPITATION, HOWEVER, IS
ANTICIPATED FOR NORTHERN CENTRAL AMERICA FROM SATURDAY THROUGH
SUNDAY, AS DEEP MOISTURE FROM THE CARIBBEAN IS TRANSPORTED INTO
THE REGION BY LOW-LEVEL TROUGHS. TOTALS ARE EXPECTED TO REACH
20-45 MM OVER HONDURAS, EL SALVADOR, AND GUATEMALA. OVER COSTA
RICA AND PANAMA, RAINFALL IS EXPECTED EACH DAY THROUGHOUT THE
FORECAST PERIOD, WITH THE CYCLONIC LOW-LEVEL FLOW ADVECTING
MOISTURE INTO THE REGION. AN INCREASE IN TOTAL RAINFALL IS
FORECASTED FOR COSTA RICA AND PANAMA FROM SATURDAY THROUGH SUNDAY
AS MOISTURE ADVECTION INCREASES, WITH TOTALS EXPECTED TO BE AROUND
25-50 MM.
TROPICAL SOUTH AMERICA:
MOST OF THE RAINFALL ACTIVITY IS ANTICIPATED TO REMAIN OVER THE
WESTERN PORTION OF THE CONTINENT, WHERE MOST OF THE MOISTURE IS
BEING ADVECTED AND LOW-LEVEL WINDS ARE CONVERGING, AFFECTING
PRIMARILY COLOMBIA AND VENEZUELA. DAILY PRECIPITATION IS
ANTICIPATED OVER COLOMBIA AND ECUADOR AS WESTERLY FLOW ADVECTS
MOISTURE FROM THE PACIFIC. ELSEWHERE, RAINFALL AND THUNDERSTORMS
DRIVEN BY DIURNAL HEATING AND LOCAL EFFECTS REMAIN LIKELY. ACROSS
THE EASTERN PORTION OF THE REGION, LOW PRECIPITABLE WATER
AVAILABILITY WILL RESULT IN DRIER CONDITIONS.
TROPICAL WAVES INITIALIZED AT 12 UTC:
SOF INIT 18/00 18/12 19/00 19/12 20/00 20/12 21/00 21/12
TW 15N 32W 35W 37W 39W 41W 42W 44W 45W 47W
TW 20N 66W 69W 71W 74W 77W DISS --- --- ---
TW 15N 112W 114W 116W 118W EXITS --- --- ---
TW 15N 104W 105W 107W 109W 110W LOW LOW LOW
RIVERA-TORRES...(WPC)
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