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FXCA20 KWBC 131906
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
306 PM EDT TUE OCT 13 2026
FORECAST BULLETIN 13 OCTOBER 2026 AT 1905 UTC:
SIGNIFICANT RAINFALL ACCUMULATION IS FORECAST TODAY FROM PANAMA
INTO NORTHWESTERN VENEZUELA.
A TROPICAL WAVE EXTENDING OVER NORTHERN COLOMBIA WILL PROVIDE
LOW-LEVEL MOISTURE CONVERGENCE FORCING, WHILE MID-LEVEL POSITIVE
POTENTIAL VORTICITY AND UPPER-LEVEL DIVERGENCE WILL SUPPORT RAPID
UPWARD MOTION AND THUNDERSTORM DEVELOPMENT OVER NORTHERN COLOMBIA
AND THE LAGO MARACAIBO REGION. AS THE MID-LEVEL CYCLONIC ROTATION
EXTENDS ACROSS THE SOUTHERN CARIBBEAN SEA, ENHANCED MID-LEVEL
POTENTIAL VORTICITY WILL INCREASE THE CHANCE OF HEAVY SHOWERS
ALONG THE SOUTHERN COAST OF PANAMA, HISPANIOLA AND EASTERN CUBA.
MODERATE RAINFALL ACCUMULATIONS ARE FORECAST TODAY ACROSS THE
REMAINDER OF CENTRAL AMERICA, THE EASTERN YUCATAN PENINSULA AND
THE SIERRA MADRE OCCIDENTAL DUE TO MID-LEVEL MOISTURE AND POSITIVE
VORTICITY ADVECTION SUPPORTING ISOLATED THUNDERSTORMS. OVER THE
NEXT THREE DAYS, THE TROPICAL WAVE WILL MOVE WESTWARD UNDER
UPPER-LEVEL DIVERGENCE AND MID-LEVEL CYCLONIC VORTICITY,
SUSTAINING SCATTERED THUNDERSTORMS FROM JAMAICA TO EASTERN YUCATAN
PENINSULA AND CENTRAL AMERICA ON WEDNESDAY AND THURSDAY.
HURRICANE SIMON IS EXPECTED TO REMAIN STATIONARY OFF WESTERN
MEXICO AS A RELATIVELY SMALL CYCLONIC CIRCULATION. A
MID-TO-UPPER-LEVEL BLOCKAGE PATTERN, CREATED BY THE ENCOUNTER OF A
RIDGE OF HIGH PRESSURE EXTENDED FROM TEXAS INTO NORTHWESTERN
MEXICO AND ANOTHER RIDGE EXTENDING FROM THE PACIFIC OVER TECOMAN
INTO SOUTHERN BAJA CALIFORNIA SUR, WILL PERSIST FOR THE NEXT TWO
DAYS. A MID-TO-UPPER-LEVEL TROUGH MOVING ACROSS THE WESTERN AND
CENTRAL U.S. OVER THE NEXT FEW DAYS WILL PROVIDE FAVORABLE
DYNAMICS FOR STRONG UPWARD MOTIONS AND HEAVY THUNDERSTORMS ACROSS
SINALOA INTO COAHUILA ON WEDNESDAY AND THURSDAY. DAILY RAINFALL
ACCUMULATION MAXIMA IN THE RANGE OF 30-60 MM ARE LIKELY. FOLLOWING
THE PASSAGE OF THIS TROUGH, THE BLOCKAGE PATTERN WILL WEAKEN,
ALLOWING A REMAINING MID-TO-UPPER-LEVEL CUT-OFF LOW TO CAPTURE
HURRICANE SIMONâ€S CIRCULATION AND STEER IT OUTWARD.
TROPICAL DEPRESSION TWENTY-ONE E WILL CONTINUE MOVING OFFSHORE
SOUTHWESTERN MEXICO OVER THE NEXT THREE DAYS. AS THIS SYSTEM
STRENGTHENS AND TRACKS OFFSHORE, ITS INDUCED OUTER CIRCULATION
WILL ADVECT A DENSE PLUME OF MOISTURE AND CYCLONIC VORTICITY
ACROSS GUATEMALA INTO TAMAULIPAS, AIDING THE DEVELOPMENT OF
SCATTERED THUNDERSTORMS ON THURSDAY. RAINFALL ACCUMULATION TOTALS
OF 15-30 MM ARE FORECAST.
SCATTERED MID-LEVEL POSITIVE POTENTIAL VORTICITY OVER ORINOQUIA
AND THE NORTHWESTERN AND CENTRAL AMAZON BASINS, COMBINED WITH
STRONG LOW-LEVEL MOISTURE CONVERGENCE WILL FAVOR THUNDERSTORM
ACTIVITY OVER THE NEXT THREE DAYS. DAILY RAINFALL MAXIMA OF 20-35
MM ARE EXPECTED AS THE PLUME OF MORE SATURATED AIR DRIFTS
WESTWARD, SHIFTING HIGHER ACCUMULATIONS FROM CANAIMA INTO THE
NORTHWESTERN AND WESTERN AMAZON BASINS BY THURSDAY. MODERATE
SHOWERS ARE FORECAST TODAY AND WEDNESDAY ALONG THE PACIFIC COAST,
BECOMING HEAVIER BY THURSDAY AS LOW-LEVEL WINDS ORGANIZE AND
ADVECT MOISTURE IN A MORE ZONAL ORIENTATION OVER THE EASTERN
COLOMBIAN AND ECUADORIAN ANDES.
TROPICAL WAVES INITIALIZED AT 12 UTC:
TYP SOF INIT 14/00 14/12 15/00 15/12 16/00 16/12 17/00 17/12
TW 20N 51W 53W 57W 60W 62W 66W 69W 72W 74W
TW 16N 76W 78W 79W 81W 82W 84W 86W 87W 89W
SANCHEZ-PEREZ...(WPC)
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