TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
300 PM EDT TUE APR 23 2024

FORECAST BULLETIN 23 APR 2024 AT 1900 UTC: A POTENT MID/UPPER
POLAR TROUGH IS PROPAGATING EASTWARD ACROSS THE WESTERN NORTH
ATLANTIC. THIS TROUGH IS SUSTAINING A SURFACE FRONT THAT IS
PROPAGATING RAPIDLY ACROSS THE BAHAMAS. BY TUESDAY EVENING EXPECT
THE BOUNDARY ACROSS THE SOUTHEAST BAHAMAS...NORTHERN CUBA...INTO A
WEAKENING BOUNDARY ACROSS THE SOUTHEAST GULF OF MEXICO. BY TUESDAY
EVENING...EXPECT THE BOUNDARY TO BECOME STATIONARY ACROSS THE
SOUTHEAST BAHAMAS...CENTRAL CUBA...WHERE IT IS TO MEANDER THROUGH
FRIDAY. THE SYSTEM WILL ALSO ASSOCIATE WITH A SHEAR LINE. BY
TUESDAY EVENING IT IS FORECAST ACROSS EASTERN HISPANIOLA. AFTER
THIS PERIOD...EXPECT IT TO GRADUALLY WEAKEN WHILE MEANDERING
NORTHWESTWARD. THE HEAVIEST PRECIPITATION WITH THESE SYSTEMS WILL
CLUSTER IN THE WARM SIDE OF THE SHEAR LINE AND ALONG A PREFRONTAL
TROUGH STRUCTURE...GIVEN THE PRESENCE OF PRECIPITABLE WATER VALUES
NEAR/ABOVE 50MM...WHICH IS ABOVE AVERAGE FOR THIS TIME OF THE
YEAR. ON TUESDAY...EXPECT 15-20MM/DAY AND MAXIMA OF 30-60MM IN
HISPANIOLA IN ASSOCIATION WITH THE SHEAR LINE. ALSO OF
RELEVANCE...FRONTAL CONVECTION/PREFRONTAL CONVECTION IN CENTRAL
CUBA HAS A POTENTIAL OF BECOMING SEVERE. EXPECT ACCUMULATION
GENERALLY IN THE 05-10MM/DAY AND MAXIMA OF 15MM RANGE...ALTHOUGH
VERY ISOLATED HIGHER AMOUNTS ARE POSSIBLE. IN PUERTO RICO...THE
PREFRONTAL TROUGH STRUCTURE WILL FAVOR MAXIMA OF 15-30MM. ON
WEDNESDAY...EXPECT THE HEAVIEST PRECIPITATION IN CENTRAL
HISPANIOLA WHERE DIURNAL CONVECTION INTERACTING WITH THE SHEAR
LINE WILL FAVOR 10-15MM/DAY AND MAXIMA OF 20-45MM. EXPECT SIMILAR
AMOUNTS IN PUERTO RICO...WHILE IN CUBA...EXPECT ISOLATED MAXIMA OF
15-25MM IN THE TAIL OF THE STATIONARY FRONT. ON THURSDAY...EXPECT
HEAVY THUNDERSTORMS IN HISPANIOLA THE PREFRONTAL TROUGH AND
ASSOCIATED MOIST PLUME MOVE WESTWARD...AND INTERACT WITH THE UPPER
DIVERGENT PATTERN AHEAD OF A POLAR TROUGH. THIS WILL FAVOR
25-50MM/DAY AND ISOLATED MAXIMA OF 75-150MM.

TO THE EAST...THE AMPLIFIED MID/UPPER PATTERN ACROSS THE ATLANTIC
HAS ORGANIZED ANOTHER EXTENSIVE SURFACE FRONT. AS THE ASSOCIATED
POLAR HIGH BUILDS...THIS FRONT IS FORECAST TO CONTINUE MEANDERING
SOUTHWARD RAPIDLY. ALTHOUGH IT IS FORECAST TO GRADUALLY LOSE
BAROCLINICITY...THE FORECAST THERMAL GRADIENT APPEARS SUFFICIENT
TO CONSIDER A COLD FRONT OR FRONTAL SHEAR LINE AS IT MEANDERS INTO
THE SOUTHERN WINDWARD ISLANDS BY THURSDAY. REGARDLESS...EXPECT A
TEMPORARY ENHANCEMENT OF TRADE WIND SHOWERS AS IT PROPAGATES
ACROSS THE LEEWARDS AND CENTRAL LESSER ANTILLES ON WEDNESDAY...AND
ACROSS THE SOUTHERN WINDWARD ISLANDS ON THURSDAY.

ANOTHER REGION OF INTEREST SOUTHERN CENTRAL AMERICA/NORTHWEST
COLOMBIA. IN THE UPPER LEVELS...THE DOMINANT FEATURE IS THE
SUBEQUATORIAL RIDGE. AS IT INTERACTS WITH AN UNSEASONABLY STRONG
SUBTROPICAL RIDGE/BOLIVIAN HIGH IN SOUTH AMERICA...AN ENHANCED
UPPER DIVERGENT TIER CONTINUES OVER COLOMBIA AND IS EXPANDING INTO
SOUTHERN CENTRAL AMERICA. IN THE LOW AND MID-LEVELS...A TROUGH IS
ORGANIZING IN CENTRAL PORTIONS OF COLOMBIA AND IS FORECAST TO
MEANDER WESTWARD INTO SOUTHERN CENTRAL AMERICA THROUGH
THURSDAY/FRIDAY. IN A SLOW-TO-EVOLVE PROGRESSION...EXPECT MODERATE
RAINFALL AMOUNTS DEVELOPING WITH THIS SYSTEM. ON TUESDAY...THE
HEAVIEST PRECIPITATION IS EXPECTED IN NORTHERN COLOMBIA/LAKE
MARACAIBO REGION WHERE ENHANCED MOISTURE CONVERGENCE WILL FAVOR
15-20MM/DAY AND ISOLATED MAXIMA OF 35-70MM. IN THE MEAN
TIME...ONSHORE FLOW IN THE CARIBBEAN BASINS OF COSTA RICA AND
PANAMA WILL FAVOR 10-15MM/DAY AND ISOLATED MAXIMA OF 20-45MM. ON
WEDNESDAY...EXPECT 15-20MM/DAY AND MAXIMA OF 40-80MM DEVELOPING IN
THE DARIEN REGION/NORTHWEST COLOMBIA AND ALSO IN THE CARIBBEAN
BASIN OF WEST PANAMA. ON THURSDAY...EXPECT POTENTIAL AMOUNTS OF
15-20MM/DAY AND MAXIMA OF 50-100MM.

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