973
FXCA20 KWBC 282005
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
404 PM EDT MON SEP 28 2026
FORECAST BULLETIN 28 SEPTEMBER 2026 AT 2000 UTC:
MEXICO AND NORTHERN CENTRAL AMERICA . . .
A MID-TO-UPPER-LEVEL TROUGH EXTENDED OVER CALIFORNIA WILL CARRY
HURRICANE (H.) ODALYS' MOISTURE REMNANTS INTO NORTH AMERICA AND
WILL PROVIDE UPPER-LEVEL DIVERGENCE SUPPORT FROM BAJA CALIFORNIA
TO NORTHERN MEXICAN ALTIPLANO TODAY. LOCAL OROGRAPHY WILL INTERACT
WITH THIS TRANSPORTED MOISTURE TO TRIGGER MODERATE SHOWERS FROM
BAJA CALIFORNIA TO NORTHERN CHIHUAHUA. THE AFOREMENTIONED TROUGH
WILL INTERACT ON ITS EASTERN FLANK WITH A MID-TO-UPPER-LEVEL
HIGH-PRESSURE SYSTEM, WITH ITS NORTHERN RIDGE CURRENTLY EXTENDED
FROM WESTERN TO NORTHERN MEXICO, TO CREATE A CHANNEL THAT WILL
DRIVE HURRICANE POLO INTO BAJA CALIFORNIA SUR AND THE CENTRAL
SONORA COAST TODAY. RAINFALL ACCUMULATION MAXIMA OF 50-100 MM ARE
FORECAST OVER THIS AREA. ON TUESDAY, TROPICAL CYCLONE (T.C.) POLO
WILL MAKE LANDFALL IN SONORA, WHERE IT IS EXPECTED TO DISSIPATE.
HEAVY RAINFALL WITH MAXIMUM ACCUMULATION IN THE RANGE OF 50-100 MM
IS LIKELY OVER SONORA AND PORTIONS OF EASTERN CHIHUAHUA AND
NORTHWESTERN SINALOA.
OFF THE COAST OF SOUTHWESTERN MEXICO, TROPICAL STORM (T.S.) RACHEL
SUPPORTS LOW-LEVEL MOISTURE TRANSPORT INTO THE SIERRA MADRE DEL
SUR AND THE MID-SOUTHERN EJE VOLCANICO TRANSVERSAL, WHICH WILL
INTERACT WITH LOCAL TERRAIN TO FORCE MODERATE AND LOCALLY HEAVY
STORMS. THE SOUTHERN FLANK OF THE MID-LEVEL HIGH WILL KEEP T.S.
RACHEL'S MAIN CIRCULATION OFFSHORE MOVING NORTHWESTWARD TODAY.
OVER THE NEXT FEW DAYS, A SECOND RIDGE WILL DEVELOP AND EXTEND
FROM SOUTHERN TO NORTHERN MEXICO, KEEPING T.C. RACHEL'S MAIN
CIRCULATION OFFSHORE. THE OUTER CIRCULATION OF T.C. RACHEL WILL
SUPPORT COASTAL HEAVY RAINFALL FROM GUERRERO TO JALISCO WITH DAILY
RAINFALL MAXIMA OF 25-50 MM.
ON THE PERIPHERY OF T.S. RACHEL'S CIRCULATION, SOUTHERLY LOW-LEVEL
WINDS WILL ADVECT MOISTURE FROM THE PACIFIC INTO THE SIERRA MADRE
DE CHIAPAS. LOCAL OROGRAPHY AND A LOW-LEVEL TROUGH OVER THE
YUCATAN PENINSULA WILL TRIGGER SHOWERS FROM CHIAPAS TO CAMPECHE
AND INTO EASTERN HONDURAS. LOWER-LEVEL WINDS WILL STRENGTHEN OVER
THE WESTERN CARIBBEAN BASIN, INCREASING MOISTURE TRANSPORT OVER
THE REGION ON TUESDAY, WHILE A LOW-LEVEL TROUGH DEVELOPS IN THE
AFTERNOON TO INCREASE MOISTURE CONVERGENCE. IN THE UPPER LEVELS, A
TROUGH WILL DIG OVER THE EASTERN YUCATAN PENINSULA, SUPPORTING
RAIN-FAVORING DYNAMICS BENEATH AND A MARGINAL RISK OF SEVERE
WEATHER. LOW-LEVEL MOISTURE DIVERGENCE WILL DEVELOP OVER THE
REGION BY WEDNESDAY, LEADING TO MORE MODERATE RAINFALL
ACCUMULATIONS WITH ISOLATED THUNDERSTORMS.
THE BAHAMAS AND CARIBBEAN . . .
AN UPPER-LEVEL TROUGH EXTENDS FROM THE EASTERN GULF TO THE WESTERN
CARIBBEAN SEA, DRIVING AN INCREASE IN UPPER-LEVEL DIVERGENCE OVER
WESTERN CUBA. MODERATE LOWER-LEVEL MOISTURE CONVERGENCE IN THE
AREA WILL FEED ISOLATED STORMS AND MAXIMUM RAINFALL ACCUMULATIONS
OF 15-25 MM. THE UPPER-LEVEL TROUGH WILL DIG ON TUESDAY, SHOWING A
MORE ORGANIZED MID-LEVEL REFLECTION AND FAVORING STRONG
UPPER-LEVEL DIFFLUENCE OVER CENTRAL-TO-WESTERN CUBA AND MODERATE
SHOWERS OVER THE EAST. A LOW-LEVEL TROUGH WILL DEVELOP OVER THE
YUCATAN PENINSULA INTO WESTERN CUBA, AND A SECOND WILL DO IT OVER
CENTRAL CUBA TO INCREASE LOW-LEVEL MOISTURE CONVERGENCE. THIS
SETUP WILL LEAD TO CONVECTIVE STORMS AND A MARGINAL RISK OF SEVERE
WEATHER, WITH DAILY RAINFALL ACCUMULATION MAXIMA OF 20-35 MM OVER
WESTERN CUBA AND UP TO 15 MM FURTHER EAST INTO THE BAHAMAS.
FAVORABLE UPPER-LEVEL DYNAMIC CONDITIONS WILL REMAIN EXTENDED OVER
MOST OF THE CUBAN TERRITORY, BLOCKED ON ITS EASTERN FLANK BY A
STRONG MID-TO-UPPER-LEVEL RIDGE EXTENDING OVER HISPANIOLA INTO THE
EASTERN ATLANTIC ON WEDNESDAY. MODERATE TO STRONG LOW-LEVEL WINDS
WILL INTERACT WITH LOCAL TERRAIN TO DEVELOP A SERIES OF TROUGHS,
INCREASING LOW-LEVEL MOISTURE CONVERGENCE AND TRIGGERING ISOLATED
HEAVY THUNDERSTORMS OVER CUBA AND THE BAHAMAS.
A TROPICAL WAVE EXTENDED OVER THE WINDWARD ISLANDS TODAY IS
PROVIDING LOW-LEVEL MOISTURE FORCING WHILE SUPPORTED BY A
MID-TO-UPPER-LEVEL TROUGH TO GENERATE MODERATE RAINFALL TOTALS.
ANOTHER TROPICAL WAVE IS EXPECTED TO MOVE OVER THE WINDWARD
ISLANDS ON WEDNESDAY, INCREASING THE CHANCE OF MODERATE RAINFALL
ACCUMULATIONS.
NORTHERN SOUTH AMERICA AND SOUTHERN CENTRAL AMERICA . . .
LOCAL OROGRAPHY WILL FAVOR MODERATE LOW-LEVEL MOISTURE CONVERGENCE
OVER THE COLOMBIAN AND ECUADORIAN ANDES. UPPER-LEVEL DIVERGENCE
WILL ENHANCE UPWARD MOTION OVER NORTHERN COLOMBIA, WHERE HEAVIER
PRECIPITATION IS LIKELY TODAY. LOWER-LEVEL MOISTURE DIVERGENCE
WILL DEVELOP OVER THE MID-SOUTHERN COLOMBIAN ANDES INTO THE
NORTHWEST AND WEST AMAZON. STRONG LOW-LEVEL WINDS WILL ADVECT
AVAILABLE MOISTURE OVER THE PANAMA BIGHT INTO NORTHERN ECUADOR AND
THE PACIFIC COLOMBIAN COAST TO DRIVE OROGRAPHIC PRECIPITATION ON
TUESDAY. A TROPICAL WAVE WILL MOVE INTO NORTHERN COLOMBIA ON
WEDNESDAY TO ENHANCE LOW-LEVEL MOISTURE CONVECTION AND TRIGGER
SCATTERED STORMS OVER THE CARIBBEAN REGION, WHILE LOCAL OROGRAPHY
FAVORS INSTABILITY OVER THE ANDES AND ALONG THE PACIFIC COAST.
LOCAL TERRAIN FORCING AND LOW-LEVEL WIND CONFLUENCE WILL LEAD TO
STRONG LOW-LEVEL MOISTURE CONVERGENCE OVER CANAIMA AND RORAIMA
TODAY. MODERATE LOW-LEVEL MOISTURE CONVERGENCE IS EXPECTED OVER
THE CENTRAL AMAZON BASIN TODAY AND WILL LINGER ON TUESDAY,
LIMITING CONVECTIVE PRECIPITATION OVER THE REGION. BY WEDNESDAY,
AN EXTENDED AREA OF LOW-LEVEL CONVERGENT WINDS WILL INCREASE
UPWARD MOISTURE TRANSPORT OVER THE CENTRAL AMAZON BASIN TO TRIGGER
SCATTERED STORMS. RAINFALL ACCUMULATION MAXIMA OF 15-25 MM ARE
FORECAST.
THE MONSOON TROUGH AND A TROPICAL WAVE EXTENDING ALONG EASTERN
NICARAGUA AND COSTA RICA WILL PROVIDE LOW-LEVEL SUPPORT FOR
MODERATE MOISTURE CONVERGENCE OVER THE REGION. THIS SETUP WILL
TRIGGER THUNDERSTORMS AND MAXIMUM DAILY RAINFALL ACCUMULATIONS OF
15-25 MM. OVER THE NEXT FEW DAYS, THE MONSOON TROUGH WILL BE THE
PRIMARY DRIVER OF MOISTURE CONVERGENCE, LEADING TO LIGHT TO
MODERATE RAINFALL ACCUMULATIONS OVER SOUTHERN CENTRAL AMERICA.
TROPICAL WAVES INITIALIZED AT 12 UTC:
TYP SOF INIT 29/00 29/12 30/00 30/12 01/00 01/12 02/00 02/12
TW 22N 51W 54W 56W 58W 60W 62W 65W 68W 71W
TW 15N 60W 63W 65W 69W 71W 73W 75W 76W 78W
TW 15N 83W 85W 87W 88W DISS --- --- --- ---
SANCHEZ-PEREZ...(WPC)
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