824
FXCA20 KWBC 131905
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
305 PM EDT THU AUG 13 2026
FORECAST BULLETIN 13 AUGUST 2026 AT 1910 UTC:
BROAD AREAS OF SIGNIFICANT RAINFALL ACCUMULATION ARE EXPECTED
ACROSS ORINOQUIA INTO CENTRAL AMERICA THROUGHOUT THE NEXT THREE
DAYS ASSOCIATED WITH THE PASSAGE OF A SERIES OF TROPICAL WAVES.
HEAVY RAINFALL IS EXPECTED ACROSS LESSER ANTILLES BY SATURDAY WITH
THE ARRIVAL OF A TROPICAL WAVE.
MEXICO AND NORTHERN CENTRAL AMERICA . . .
AN UPPER-TO-MID-LEVEL LOW IS CURRENTLY CENTERED OVER NORTHEASTERN
MEXICO AND A MID-LEVEL TROUGH EXTENDS OVER WESTERN TO SOUTHWESTERN
MEXICO. THIS PATTERN, WORKING IN TANDEM WITH DIURNAL HEATING AND
NORTH AMERICAN MONSOON SETUP, WILL SUPPLY LOWER LEVEL MOISTURE
CONVERGENCE AND UPPER LEVEL DIVERGENCE TO SUPPORT ISOLATED HEAVY
RAINFALL FROM NORTHWESTERN TO SOUTHEASTERN AND SOUTH-CENTRAL
MEXICO TODAY. AS THIS UPPER LEVEL PATTERN MOVES NORTHWESTWARD, IT
WILL CONTINUE PROVIDING THE UPPER LEVEL DYNAMIC SUPPORT TO AND
WILL DRIFT THESE ISOLATED HEAVY PRECIPITATION AREAS NORTHWESTWARD.
BY FRIDAY, A TROPICAL WAVE WILL MOVE INTO NORTHERN CENTRAL
AMERICA AND YUCATAN PENINSULA TO ENHANCE LOWER LEVEL MOISTURE
CONVERGENCE TO INTERACT WITH THE REGIONAL TOPOGRAPHY TO INCREASE
DAILY RAINFALL ACCUMULATION MAXIMA ACROSS THE REGION.
THIS INCREASE IN RAINFALL ACCUMULATION WILL BE ESPECIALLY HIGHER
ON SATURDAY FROM VERACRUZ TO WESTERN HONDURAS WHERE 15 - 35 MM
ARE EXPECTED.
THE BAHAMAS AND CARIBBEAN . . .
A TROPICAL WAVE EXTENDS ITS AXIS FROM CUBA TO PANAMA AND A SECOND
ONE DOES FROM HISPANIOLA TO VENEZUELA SUPPORTING LOWER-LEVEL
MOISTURE CONVERGENCE. AN UPPER-LEVEL CUT-OFF LOW IS CENTERED
BETWEEN HAITI AND TURKS AND CAICOS SUPPORTING WIND DIVERGENCE
ALOFT THIS REGION. THIS DYNAMICAL SETUP WILL INTERACT WITH THE
DIURNAL HEATING AND MESOSCALE LOW LEVEL FORCING TO BRING ISOLATED
AREAS OF HEAVY RAIN OVER CENTRAL-EASTERN CUBA, NORTHWESTERN
HISPANIOLA AND MODERATE OVER SOUTHEASTERN BAHAMAS TODAY.
ON FRIDAY, THE UPPER-LEVEL DISTURBANCE WILL DRIFT WESTWARD AND
WILL FAVOR UPDRAFTS OVER CENTRAL-WESTERN CUBA WHILE THE TROPICAL
WAVE WILL PROVIDE MOISTURE CONVERGENCE BENEATH. A THIRD TROPICAL
WAVE WILL MOVE IN THE REGION LATE SATURDAY AND WILL INTERACT WITH
UPPER LEVEL WIND DIVERGENCE ASSOCIATED WITH AN UPPER LEVEL TROUGH
EXTENDED OVER LESSER ANTILLES. A BOOST IN HEAVY RAINFALL CHANCES
IS EXPECTED DUE TO THIS PATTERN OVER THE REGION WITH DAILY
ACCUMULATION MAXIMA OF 20 - 50 MM.
NORTHERN SOUTH AMERICA AND SOUTHERN CENTRAL AMERICA . . .
THE TROPICAL WAVE EXTENDS OVER THE CARIBBEAN BASIN, IN INTERACTION
WITH THE MONSOON TROUGH ACROSS SOUTHERN CENTRAL AMERICA. A
LOWER-LEVEL TROUGH EXTENDS ALONG WESTERN COLOMBIA AND TOPOGRAPHIC
FORCING, ALL IN INTERACTION, CREATES FAVORABLE CONDITIONS TO
MODERATE MOISTURE CONVERGENCE IN THE LOW TROPOSPHERE. AN
UPPER-LEVEL LOW PRESSURE CIRCULATION IS CENTERED OVER SOUTHWESTERN
COLOMBIA, BUT UPPER-LEVEL DIFFLUENCE IS NOT SIGNIFICANT, SO
PRECIPITATION TOTALS WILL BE LIMITED TODAY TO 15-30 MM MAXIMUM.
SIMILAR CONDITIONS AND RAINFALL TOTALS ARE EXPECTED OVER
ORINOQUIA.
ON FRIDAY, AS THE TROPICAL WAVES AND THE UPPER-LEVEL
COUNTERCLOCKWISE CIRCULATION MOVE WESTWARD AND NORTHWESTWARD,
CREATING MORE FAVORABLE DYNAMIC CONDITIONS FOR RAINFALL. ONE
TROUGH WILL BE EXTENDED OVER HONDURAS INTO THE PACIFIC AND THE
SECOND ONE OVER PANAMA, THIS PATTERN IN CONJUNCTION WITH MONSOON
TROUGH CIRCULATION, WILL SUPPORT PWAT ANOMALIES EXCEEDING 2
STANDARD DEVIATIONS. AN AREA OF UPPER-LEVEL DIFFLUENCE WILL
SUPPORT ASCENT OVER NORTHERN TO NORTHWESTERN AND SOUTHWESTERN
COLOMBIA. THIS WILL LEAD TO A RAIN ACCUMULATION MAXIMUM OF 20-50MM
FROM EASTERN CENTRAL AMERICA TO WESTERN COLOMBIA. A LOWER-LEVEL
TROUGH OVER ORINOQUIA WILL BRING AN INCREASE IN RAINFALL TOTALS
AND DEEP CONVECTION IS POSSIBLE.
A THIRD TROPICAL WAVE WILL ENTER THE REGION LATE ON FRIDAY TO
INCREASE THE RAIN CHANCES OVER NORTHEASTERN VENEZUELA AND NORTHERN
GUYANA. ON SATURDAY THIS TROPICAL WAVE WILL SUPPORT PRECIPITATION
ACROSS VENEZUELA. OVER SOUTHERN CENTRAL AMERICA, A LOWER-LEVEL
ENCLOSED CIRCULATION IS EXPECTED TO DEVELOP AND THE UPPER-LEVEL
LOW WILL BECOME BETTER ORGANIZED, PROVIDING SUFFICIENT DYNAMICAL
SUPPORT. THESE CONDITIONS WILL LEAD TO RAINFALL MAXIMA OF 35-70 MM
LIKELY ACROSS THE REGION AND MAY BE LOCALLY HIGHER DUE TO
TOPOGRAPHIC FORCING.
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 15N 44W 48W 52W 56W 60W 64W 69W 74W 78W
TW 18N 69W 74W 77W 81W 85W 88W 92W 96W 100W
TW 18N 79W 82W 86W 90W 94W 98W 103W 108W 112W
TW 10N 95W 100W 104W 109W 113W 117W EXITS
SANCHEZ-PEREZ...(WPC)
TINOCO-MORALES...(WPC)
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