464  
FXCA20 KWBC 251835  
PMDCA  
 
TROPICAL DISCUSSION - INTERNATIONAL DESKS  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
234 PM EDT TUE APR 25 2023  
 
FORECAST BULLETIN FROM 25 APR 2023 AT 1830 UTC: IN MEXICO...AN  
UPPER TROUGH IS EXPECTED TO APPROACH FROM THE WEST LATE ON  
WEDNESDAY. THIS WILL ACTIVATE DIURNAL CONVECTION ALONG NORTHERN  
PORTIONS OF THE SIERRA MADRE ORIENTAL. HOWEVER...LIMITED AMOUNTS  
OF AVAILABLE MOISTURE WILL LIMIT THE COVERAGE OF AFTERNOON/EVENING  
THUNDERSTORMS. ON THURSDAY...A ROBUST UPPER TROUGH IN THE PLAINS  
OF THE USA WILL PUSH A SURFACE COLD FRONT SOUTHWARD. BY THURSDAY  
EVENING THE FRONT IS EXPECTED ACROSS LOUISIANA INTO NORTHERN  
TAMAULIPAS...CENTRAL NUEVO LEON. THIS WILL FAVOR 05-10MM/DAY AND  
MAXIMA OF 15MM IN NORTHEAST MEXICO...AND 05-10MM/DAY AND MAXIMA OF  
15-20MM ALONG CENTRAL PORTIONS OF THE SIERRA MADRE ORIENTAL.  
YET...THE HEAVIEST PRECIPITATION WITH THIS SYSTEM IS EXPECTED IN  
PORTIONS OF THE NORTHERN GULF OF MEXICO/SOUTHEAST USA.  
OTHERWISE...DIURNAL CONVECTION IS EXPECTED ON A DAILY BASIS IN  
OAXACA/PUEBLA/SOUTHERN SIERRA MADRE ORIENTAL TO PRODUCE MAXIMA  
GENERALLY UNDER 15-20MM/DAY.  
 
IN NORTHERN CENTRAL AMERICA...A MOIST POOL CONTINUES LINGERING  
FROM SOUTHERN HONDURAS INTO CHIAPAS. THIS WILL FAVOR DIURNAL DEEP  
CONVECTION ON A DAILY BASIS. AS SURFACE PRESSURES DECREASE IN THE  
GULF OF MEXICO ON WEDNESDAY...SOUTHERLY LOW-LEVEL WINDS ARE  
EXPECTED TO DEVELOP IN THE PACIFIC BASIN...WHICH WILL FAVOR A PEAK  
IN CONVECTION AND ACCUMULATIONS. ON TUESDAY EXPECT 10-15MM/DAY AND  
MAXIMA OF 20-35MM. ON WEDNESDAY THIS PEAKS AT 15-20MM/DAY AND  
MAXIMA OF 25-50MM IN GUATEMALA/NORTHWEST EL SALVADOR...WHILE IN  
SOUTHERN HONDURAS/EL SALVADOR EXPECT 10-15MM/DAY AND MAXIMA OF  
20-35MM. ON THURSDAY THIS DECREASES TO 05-10MM/DAY AN DMAXIMA OF  
15-20MM...ALTHOUGH HIGHER AMOUNTS ARE POSSIBLE IN CENTRAL HONDURAS.  
 
OVER THE CARIBBEAN/BAHAMAS...ZONAL WESTERLY FLOW IS FORECAST TO  
PERSIST THROUGH THE FORECAST CYCLE. IN THE MID-LEVELS...A RIDGE  
WILL CONTINUE TO BE DOMINANT IN AREAS WEST WHILE A BROAD TROUGH  
PATTERN EXTENDS OVER THE EASTERN/NORTHEAST CARIBBEAN. AVAILABILE  
MOISTURE IS...YET...LIMITED. THIS WILL LIMIT POTENTIAL RAINFALL  
ACCUMULATIONS ON A DAILY BASIS. THE MID-LEVEL RIDGE IS FORECAST TO  
ROLL EASTWARD ON THURSDAY...WHICH WILL FAVOR A STRENGTHENING OF  
THE TRADE WIND CAP OVER THE BAHAMAS...NORTHERN HISPANIOLA AND  
CUBA...LIMITING VERTICAL DEVELOPMENT. IN THE LOW-LEVELS...A  
WEAKENING STATIONARY FRONT EXTENDS ACROSS THE LEEWARD ISLANDS INTO  
16N 68W OR SOUTH OF THE MONA PASSAGE ON TUESDAY. THIS BOUNDARY IS  
RAPIDLY LOSING BAROCLINICITY...BUT IT IS FORECAST TO MEANDER NORTH  
INTO HISPANIOLA ON WEDNESDAY...TO FAVOR A TRANSIENT ENHANCEMENT OF  
ACCUMULATIONS. ON TUESDAY EXPECT 05-10MM/DAY AND MAXIMA OF 15-20MM  
IN HISPANIOLA...WHILE A SURFACE TROUGH PATTERN IN THE BAHAMAS  
FAVORS SCATTERED THUNDERSTORMS AND ACCUMULATIONS OF 05-10MM/DAY  
AND MAXIMA OF 15-25MM. ON WEDNESDAY...EXPECT A PEAK IN  
HISPANIOLA...WHERE DIURNAL CONVECTION WILL FAVOR 10-15MM/DAY AND  
MAXIMA OF 20-35MM. ON THURSDAY...THIS DECREASS TO 05-10MM/DAY AND  
MAXIMA OF 15-25MM IN HISPANIOLA...WHILE LESSER AMOUNTS ARE  
EXPECTED ELSEWHERE.  
 
IN THE LESSER ANTILLES...ACTIVE CONVECTION IS EXPECTED TO CONTINUE  
IN THE WINDWARD ISLANDS AS AN INDUCED TROUGH AND ASSOCIATED MOIST  
PLUME CONTINUE LINGERINR IN THE REGION. A PREFRONTAL SHEAR LINE  
EXTENDING INTO NORTHERN GUYANBA ON TUESDAY IS FORECAST TO MEANDER  
NORTHWARD...TO EXTEND INTO BARBADOS ON WEDNESDAY AND THEN  
DISSIPATE. THIS WILL FAVOR WET CONDITIONS ON A DAILY BASIS. ON  
TUESDAY EXPECT 10-15MM/DAY AND MAXIMA OF 20-45MM IN TRINIDAD AND  
TOBAGO...WHILE ELSEWHERE IN THE WINDWARD ISLANDS EXPECT  
05-10MM/DAY AND MAXIMA OF 15-20MM. ON WEDNESDAY...EXPECT  
10-15MM/DAY AND MAXIMA OF 20-35MM IN MOST OF THE WINDWARD ISLANDS  
NORTH INTO MARTINIQUE. IN THE LEEWARD ISLANDS EXPECT 05-10MM/DAY  
AND MAXIMA OF 15-20MM FAVORED BY THE INDUCED TROUGH. ON  
THURSDAY...EXPECT A DECREASE TO 05-10MM/DAY AND MAXIMA OF 15-25MM  
IN THE CENTRAL AND SOUTHERN LESSER ANTILLES.  
 
IN NORTHERN SOUTH AMERICA...VENTILATION WILL REMAIN FAVORABLE FOR  
DEEP CONVECTION AS COLOMBIA...VENEZUELA...NORTHERN BRASIL AND THE  
GUIANAS CONTINUE ALONG THE SOUTHERN FRINGES OF THE SUBEQUATORIAL  
RIDGE. A KELVIN WAVE IS EXITING FROM NORTHEAST SOUTH AMERICA INTO  
THE TROPICAL ATLANTIC. THIS WILL STILL FAVOR LOCALLY HEAVY  
RAINFALL IN THE GUIANAS ON TUESDAY AND WEDNESDAY...WHERE EXPECT  
15-20MM/DAY AND MAXIMA OF 40-80MM. AS THE WAVE EXITS...EXPECT A  
DECREASING TREND AFTER...ALTHOUGH THURSDAY AMOUNTS WILL REACH  
35-70MM/DAY IN MAXIMA. TO THE WEST...MOISTURE CONVERGENCE ALONG  
THE ANDEAN RANGE WILL FAVOR MODERATE AMOUNTS IN CENTRAL COLOMBIA  
ON TUESDAY...WHERE EXPECT 15-20MM/DAY AND MAXIMA OF 25-50MM.  
ACTIVE CONVECTION IS ALSO EXPECTED TO PERSIST ACROSS MOST OF  
VENEZUELA INTO RORAIMA...WHERE A DEEP-LAYER MOIST POOL WILL FAVOR  
SCATTERED THUNDERSTORMS AND AMOUNTS OF 10-15MM/DAY AND MAXIMA OF  
20-45MM. THROUGH THURSDAY...EXPECT A RELOCATION OF AREAS OF  
HEAVIEST PRECIPITATION INT WESTERN COLOMBIA AND THE PACIFIC BASIN  
OF ECUADOR...WHERE ENHANCED ONSHORE FLOW WILL FAVOR 15-20MM/DAY  
AND MAXIMA OF 40-80MM. ELSEWHERE IN ECUADOR AND NORTHERN PERU  
EXPECT 10-15MM/DAY AND MAXIMA OF 20-45MM. ALSO ON THURSDAY...AN  
ILL-DEFINED TROUGH IN CENTRAL/EASTERN VENEZUELA WILL FAVOR  
10-15MM/DAY AND MAXIMA OF 20-45MM IN MOST OF VENEZUELA...WHILE IN  
COLOMBIA EXPECT 10-15MM/DAY AND MAXIMA OF 20-35MM.  
 
GALVEZ/ACOSTA...WPC (USA)  
 

 
 
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