TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1142 AM EDT MON APR 29 2024

FORECAST BULLETIN 29 APR 2024 AT 1630 UTC: THE MJO IS EXPECTED TO
CONTINUE WEEKLY CONVERGENT IN THE UPPER LEVELS THROUGH THE
FORECAST CYCLE. UNDER THIS PATTERN...EXPECT AREAS OF POTENTIALLY
HEAVY PRECIPITATION TO REMAIN MOSTLY DISCRETE IN EXTENSION.

WEST IN THE DOMAIN...A CELL OF THE SUBEQUATORIAL RIDGE IS EXPECTED
TO PERSIST NEAR 10-13N AND 98-102W THROUGH THE CYCLE. THE RIDGE
WILL LIMIT THE PROGRESSION OF MID-UPPER TROUGHS IN
MEXICO...FAVORING THE PERSISTENCE OF A DIURNAL PATTERN IN TERMS OF
CONVECTIVE DEVELOPMENT. GIVEN CURRENT MOISTURE AVAILABILITY...THE
LARGEST ACCUMULATIONS ARE EXPECTED ALONG THE SIERRA MADRE
ORIENTAL...WHERE EXPECT AMOUNTS OF 05-10MM/DAY AND MAXIMA
GENERALLY IN THE 15MM/DAY RANGE. VENTILATION IN THE PERIPHERY OF
THE UPPER RIDGE WILL ALSO AID WITH THE DEVELOPMENT OF DIURNAL
CONVECTION IN PORTIONS OF NROTHERN CENTRAL AMERICA. ON MONDAY
EXPECT 10-15MM/DAY AND MAXIMA OF 20-35MM FROM WESTERN HONDURAS
INTO EAST CHIAPAS/SOUTHERN BELIZE. ON TUESDAY...EXPECT 10-15MM/DAY
AND VERY ISOLATED MAXIMA OF 20-40MM FROM SOUTHERN HONDURAS/EL
SALVADOR INTO SOUTHERN CHIAPAS. ON WEDNESDAY...EXPECT A DECREASE
TO 05-10MM/DAY AND ISOLATED MAXIMA OF 15-30MM.

THE PERSISTENCE OF THE UPPER RIDGE TO THE SOUTH OF MEXICO WILL
YIELD TO THE AMPLIFICATION OF AN UPPER TROUGH ACROSS THE NORTHWEST
CARIBBEAN. MODELS ARE RESOLVING THIS EVOLUTION BUT STRUGGLE IN THE
PRECISE LOCATION OF THE TROUGH AXIS AND SHAPE. THIS IS RELEVANT
FOR THE PRECIPITATION FORECAST IN JAMAICA...SOUTHEAST CUBA AND
HISPANIOLA...WHERE A MOIST PLUME IS BREWING.
FURTHERMORE...ENHANCEMENT BY A SURFACE FRONT WILL BE RELEVANT FOR
QPF. IN TERMS OF FRONTAL POSITIONS...BY MONDAY EVENING EXPECT A
BOUNDARY ALONG 20N 60W...NORTHERN PUERTO RICO...CENTRAL
HISPANIOLA...NORTHERN COAST OF CUBA. IT IS FORECAST TO REMAIN IN
THESE LOCATIONS THROUGH THE ENTIRE FORECAST CYCLE...WHILE SLOWLY
MEANDERING NORTHWARD AWAY FROM THE COASTS OF THE GREATER ANTILLES.
BY LATE WEDNESDAY...INTERACTIONS BETWEEN THE UPPER TROUGH AND THE
FRONT WILL LIKELY INDUCE A FRONTAL WAVE TO THE NORTH OF HISPANIOLA
WHILE THE FRONT LOSES DEFINITION IN AREAS TO THE WEST.

IN TERMS OF PRECIPITATION...ON MONDAY EXPECT MAXIMA OF 20-35MM IN
HISPANIOLA AND MAXIMA OF 15-20MM IN PUERTO RICO...VI AND LEEWARD
ISLANDS. IN PORTIONS OF CUBA EXPECT MAXIMA OF 15-25MM AND IN
JAMAICA MAXIMA OF 15MM. ON TUESDAY...AS THE UPPER TROUGH STARTS TO
ORGANIZE...EXPECT AN INCREASE IN ACCUMULATION. NOTE THAT A
MARGINAL RISK FOR SEVERE CONVECTION IS POSSIBLE IN PORTIONS OF
SOUTHEAST CUBA AND HAITI...WHERE INSTABILITY AND DIURNAL HEATING
MIGHT PLAY A ROLE. IN TERMS OF AMOUNTS...EXPECT MAXIMA OF 20-45MM
IN HAITI AND IN SOUTHEAST CUBA...WHILE IN PUERTO RICO...HISPANIOLA
AND JAMAICA EXPECT 10-15MM/DAY AND MAXIMA OF 20-35MM. IN CENTRAL
CUBA...EXPECT 05-10MM/DAY AND MAXIMA OF 15-25MM. BY
WEDNESDAY...EXPECT THE HEAVIEST PRECIPITATION IN HISPANIOLA DUE TO
INTERACTIONS BETWEEN THE UPPER TROUGH AND THE MOIST PLUME. EXPECT
ACCUMULATION OF 15-20MM/DAY AND MAXIMA OF 25-50MM WITH A SLIGHT
RISK OF SEVERE WEATHER. TO THE WEST OF THE MID/UPPER TROUGH
AXIS...EXPECT GENERALLY MAXIMA OF 15-20MM IN JAMAICA AND SOUTHEAST
CUBA. NOTE A SLIGHT RISK FOR SEVERITY IN SOUTHEAST CUBA. IN THE
CENTRAL/SOUTHEAST BAHAMAS AND THE TURKS AND CAICOS EXPECT ISOLATED
MAXIMA OF 15-25MM WITH A RISK FOR SQUALLY CONVECTION IN
ASSOCAITION WITH A MID-UPPER SHORT WAVE TROUGH.

SEASONAL CONVECTION IN NORTHERN SOUTH AMERICA IS CLUSTERING
GENERALLY ALONG THE ITCZ/NET AND TROUGHS PROPAGATING IN THE
TRADES. THE LARGEST ACCUMULATIONS ARE EXPECTED IN COLOMBIA...WHERE
ENHANCED MOISTURE CONVERGENCE IS EXPECTED THROUGH THE FORECAST
CYCLE. OF RELEVANCE...EXPECT AN INCREASING TREND IN WESTERN
COLOMBIA THROUGH WEDNESDAY/THURSDAY...GIVEN INCREASING
ONSHORE/WESTERLY WINDS.

GALVEZ/CLARKE/LEDESMA/ACOSTA...WPC (USA)