362
FXCA20 KWBC 181927
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
327 PM EDT TUE AUG 18 2026
FORECAST BULLETIN 18 AUGUST 2026 AT 1925 UTC:
PERSISTENT UPPER-LEVEL DYNAMIC SUPPORT AND HIGHLY ENHANCED
PRECIPITABLE WATER (PWAT) ACROSS EASTERN HONDURAS TO PANAMA WILL
SUSTAIN BROAD HIGH RAINFALL TOTALS.
MEXICO AND NORTHERN CENTRAL AMERICA . . .
A SERIES OF LOWER-LEVEL TROUGHS AND TOPOGRAPHY WILL SUPPORT
MOISTURE CONVERGENCE OVER SOUTHERN MEXICO AND NORTHERN CENTRAL
AMERICA TODAY. MODERATE UPPER-LEVEL SUPPORT AND DAILY HEATING WILL
FAVOR ISOLATED AREAS OF CONVECTIVE RAIN. OVER NORTHWESTERN MEXICO,
A WELL-STRUCTURED MID-TO-UPPER-LEVEL LOW IS INCREASING INSTABILITY
AND RAINFALL TOTALS; HOWEVER, THIS REGION WILL EXIT THE REGION
LATER TODAY. NORTH AMERICA MONSOON WILL SUPPORT PRECIPITATION
ELSEWHERE ACROSS NORTHWESTERN TO WESTERN MEXICO THROUGHOUT THE
NEXT FEW DAYS. UPPER DIVERGENCE WILL DEVELOP AND SUSTAIN DEEP
ASCENT LATER WEDNESDAY INTO EARLY THURSDAY OVER THE SOUTHWEST. A
COUPLE OF TROPICAL WAVES WILL PROMOTE MOISTURE CONVERGENCE AND
LOWER-LEVEL INSTABILITY TO BRING A SIGNIFICANT INCREASE OF
RAINFALL MAXIMA.
THE BAHAMAS AND CARIBBEAN . . .
A TROPICAL WAVE OVER THE LEEWARD ISLANDS TODAY WILL MOVE
WEST-NORTHWEST THROUGH WEDNESDAY AND THURSDAY, REACHING
HISPANIOLA. AN UPPER-LEVEL TROUGH WILL TRACK WESTWARD ALONG WITH
THIS WAVE, PROVIDING UPPER-LEVEL VENTILATION TO SUPPORT DEEP
CONVECTION. SOME DEEP CONVECTION IS EXPECTED OVER THE WINDWARD AND
ABC ISLANDS REGION THROUGH WEDNESDAY AFTERNOON.
A MID-LEVEL RIDGE OF HIGH PRESSURE NORTH OF THE GREATER ANTILLES
WILL FOLLOW THE PASSAGE OF THE TROPICAL WAVE FROM THURSDAY INTO
FRIDAY. CONSEQUENTLY, THE EASTERN CARIBBEAN WILL EXPERIENCE DRIER
AIR AND LOWER CAPPING INVERSIONS.
FROM WEDNESDAY INTO THURSDAY, A TROPICAL WAVE MOVES TOWARD THE
GREATER ANTILLES ACCOMPANIED BY HIGHER MOISTURE. AN UPPER-LEVEL
LOW DEEPENING WEST OF HISPANIOLA WILL SUPPORT DEEP CONVECTION.
LOCALIZED RAINFALL MAXIMA OF 20-45 MM ARE LIKELY OVER HISPANIOLA
ON THURSDAY. DAILY ACCUMULATION OF 5-10 MM, WITH MAXIMA OF 15-20
MM, IS FORECASTED OVER THE NEXT FEW DAYS ELSEWHERE IN THE REGION.
NORTHERN SOUTH AMERICA AND SOUTHERN CENTRAL AMERICA . . .
THE MONSOON TROUGH AND INTERTROPICAL CONVERGENCE ZONE PATTERNS
WILL SUPPORT STRONG LOW-LEVEL MOISTURE CONVERGENCE ACROSS SOUTHERN
CENTRAL AMERICA. IN THE UPPER-LEVEL, A STEADY REGION OF WIND
DIVERGENCE WILL PERSIST OVER NICARAGUA TO PANAMA THROUGH THE NEXT
FEW DAYS. THIS SETUP WILL SUPPORT RAINFALL TOTAL MAXIMA OF 30-60
MM TODAY. TOTALS WILL DECREASE SLIGHTLY ON WEDNESDAY AND THURSDAY,
BUT AN INCOMING TROPICAL WAVE WILL INCREASE LOW-LEVEL MOISTURE
CONVERGENCE FURTHER EAST INTO THE WEST OF COLOMBIA, SPREADING THE
AREA OF SIGNIFICANT RAINFALL. THE PASSAGE OF A TROPICAL WAVE OVER
ORINOQUIA WILL SUPPORT CONVECTIVE PRECIPITATIONS TODAY. A SERIES
OF LOWER LEVEL TROUGHS, HUMIDITY ADVECTION, AND DIURNAL HEATING
WILL TRIGGER SHOWERS ACROSS CENTRAL TO WESTERN AMAZON THROUGH THE
NEXT THREE DAYS, AND OVER ORINOQUIA AFTER WEDNESDAY.
TROPICAL WAVES INITIALIZED AT 12 UTC:
TYP SOF INIT 19/00 19/12 20/00 21/12 22/00 22/12 23/00 23/12
TW 15N 32W 35W 38W 41W 44W 47W 50W 53W 56W
TW 18N 65W 69W 72W 75W 78W 81W 84W 88W 93W
TW 15N 82W 86W 90W 93W 97W 100W ABS --- ---
TW 13N 89W 92W 95W 97W 101W 104W 107W 112W 115W
TW 11N 102W 105W 108W 109W 111W 113W 116W 119W ABS
TW 14N 110W 113W 116W 119W EXITS --- --- --- ---
SANCHEZ-PEREZ...(WPC)
TINOCO-MORALES...(WPC)
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