251
FXCA20 KWBC 241724
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
124 PM EDT MON APR 24 2023
FORECAST BULLETIN FROM 24 APR 2023 AT 1730 UTC: MID-UPPER ZONAL
WESTERLY FLOW IS OCCURRING AT LATITUDES NORTH OF 13N IN NORTHERN
CENTRAL AMERICA AND MEXICO. OVER MEXICO...WESTERLY MOMENTUM IS
MIXING INTO THE LOW-LEVEL FLOW...CLUSTERING REGIONS OF DIURNAL
MOISTURE CONVERGENCE TO THE SIERRA MADRE ORIENTAL. THIS WILL FAVOR
AFTERNOON DEVELOPMENT ON A DAILY BASIS ON MONDAY AND TUESDAY. ON
MONDAY...EXPECT 10-15MM/DAY AND MAXIMA OF 20-35MM...AND
05-10MM/DAY AND MAXIMA OF 15-20MM ON TUESDAY. AN UPPER TROUGH
APPROACHES FROM THE WEST ON WEDNESDAY...TO HIGHLIGHT VENTILATION
ACROSS CENTRAL AND NORTHEAST MEXICO. THIS WILL ENHANCE DIURNAL
ACTIVITY ALONG CENTRAL AND NORTHERN PORTIONS OF THE SIERRA MADRE
ORIENTAL AS WELL. BY WEDNESDAY EXPECT AN INCREASE IN THE COVERAGE
OF CONVECTION AND AMOUNTS...WHEN EXPECTING 05-10MM/DAY AND MAXIMA
OF 15-25MM FROM OAXACA ALONG THE SIERRA MADRE ORIENTAL INTO SAN
LUIS POTOSI/HIDALGO.
IN NORTHERN CENTRAL AMERICA....LOW-LEVEL MOISTURE CONVERGENCE AND
INSTABILITY REMAINS CLUSTERED BETWEEN SOUTHERN MEXICO INTO
GUATEMALA AND WESTERN HONDURAS/NORTHERN EL SALVADOR. THE UPPER
FLOW IS FORECAST TO REMAIN PRIMARILY FROM THE WEST...WITHOUT
SIGNIFICANT RAINFALL ENHANCEMENT FEATURES THROUGH THURSDAY. IN THE
MID-LEVELS...A RIDGE INITIALLY CENTERING OFF THE COAST OF SOUTHERN
MEXICO IS FORECAST TO MEANDER EASTWARD SLOWLY THROUGH EARLY
WEDNESDAY...TO THEN ACCELERATE AND CROSS INTO THE GULF OF HONDURAS
BY THURSDAY MORNING...AND INTO THE CENTRAL CARIBBEAN BY FRIDAY
MORNING. ALTHOUGH THIS EVOLUTION FAVORS A GRADUAL DECREASE IN
AMOUNTS FROM DIURNAL CONVECTION...THE APPROACH OF THE UPPER TROUGH
IN MEXICO BY WEDNESDAY WILL RESULT IN A LOWERING OF THE SURFACE
PRESSURES IN THE GULF OF MEXICO. THIS WILL IN TERM FAVOR LOW-LEVEL
SOUTHERLIES IN EL SALVADOR/GUATEMALA BY WEDNESDAY...AND AN
ACCELERATION OF THE EASTERLY TRADES ACROSS THE GULF OF HONDURAS.
THIS WILL RESULT IN ENHANCED LOW-LEVEL MOISTURE CONVERGENCE BY
WEDNESDAY AFTERNOON...FAVORING AN INCREASE IN AMOUNTS. ON
MONDAY...EXPECT 15-20MM/DAY AND MAXIMA OF 25-50MM FROM CHIAPAS
INTO MOST OF CENTRAL AND SOUTHERN GUATEMALA...WHILE IN NORTHERN EL
SALVADOR AND SOUTHERN HONDURAS EXPECT 05-10MM/DAY AND MAXIMA OF
15-25MM. ON TUESDAY...EXPECT 10-15MM/DAY AND MAXIMA OF 20-35MM
FROM SOUTHEAST CHIAPAS/GUATEMALA INTO SOUTHERN HONDURAS/NORTHERN
EL SALVADOR. ON WEDNESDAY EXPECT 15-20MM/DAY AND MAXIMA OF 25-50MM
IN SOUTHERN AND CENTRAL GUATEMALA/NORTHWEST EL SALVADOR...WHILE
ELSEWHERE IN EL SALVADOR/SOUTHERN HONDURAS AND IN CHIAPAS EXPECT
10-15MM/DAY AND MAXIMA OF 20-35MM.
TO THE EAST AND IN THE UPPER TROPOSPHERE...THE SUBEQUATORIAL RIDGE
CONTINUES EXTENDING ALONG NORTHERN SOUTH AMERICA INTO COSTA RICA
AND NICARAGUA. THIS ASSOCIATES WITH UPPER WESTERLY FLOW ACROSS THE
ENTIRE CENTRAL/NORTHERN CARIBBEAN INTO THE BAHAMAS. A SHORT WAVE
TROUGH IS PROPAGATING EASTWARD ACROSS THE CENTRAL GULF OF MEXICO
ON MONDAY. THIS WILL INTERACT WITH A SURFACE FRONT ON MONDAY
EVENING...TO HIGHLIGHT PRECIPITATION IN THE NORTHWEST BAHAMAS. BY
MONDAY EVENING THE FRONT IS EXPECTED ALONG 30N 74W...27N 77W...A
LOW NEAR LAKE OKEECHOBEE...INTO AN ILL-DEFINED BOUNDARY ACROSS THE
SOUTHEASTERN GULF OF MEXICO. THE FRONT IS FORECAST TO LOSE
BAROCLINICITY AFTER...TO FORM A TROUGH ACROSS THE EXTREME NORTHERN
BAHAMAS INTO SOUTH FLORIDA BY TUESDAY EVENING. ON MONDAY...EXPECT
10-15MM/DAY AND MAXIMA OF 20-35MM IN BIMINI...GRAND BAHAMA AND
GREAT ABACO. THIS DECREASES TO 05-10MM/DAY AND MAXIMA OF 15-25MM
ON TUESDAY...AND AN ADDITIONAL DECREASE IS EXPECTED ON WEDNESDAY.
IN THE NORTHEAST CARIBBEAN...A MID-UPPER TROUGH IS EXITING THE
REGION FROM WEST TO EAST...FAVORING A DECREASING TREND IN
ACCUMULATIONS. THIS ASSOCIATES WITH A WEAK SURFACE FRONT THAT IS
FORECAST TO STALL ACROSS THE LEEWARD ISLANDS INTO 17N 68W OR SOUTH
OF PUERTO RICO BY MONDAY EVENING. THE STATIONARY BOUNDARY IS
FORECAST TO GRADUALLY FRONTOLIZE ON TUESDAY...DISSIPATING BY
WEDNESDAY MORNING. THIS WILL...HOWEVER...DEVELOP A PREFRONTAL
SHEAR LINE THAT IS FORECAST TO EXTEND FROM THE NORTH ATLANTIC INTO
NORTHERN GUYANA BY TUESDAY EVENING. BY WEDNESDAY EVENING IT WILL
RETROGRESS TO EXTEND INTO TOBAGO AND TRINIDAD...TO THEN DISSIPATE.
ON MONDAY...EXPECT 05-10MM/DAY AND MAXIMA OF 15-30MM IN THE
WINDWARD ISLANDS IN ASSOCIATION WITH AN INDUCED TROUGH...WHILE
FRONTAL CONVECTION WILL FAVOR 05-10MM/DAY AND MAXIMA OF 15MM IN
THE LEEWARD ISLANDS AND ST. CROIX. DIURNAL CONVECTION IN SOUTHERN
PUERTO RICO AND SOUTH-CENTRAL HISPANIOLA WILL FAVOR 05-10MM/DAY
AND ISOLATED MAXIMA OF 15-25MM. SIMILAR AMOUNTS ARE EXPECTED IN
SOUTHWEST JAMAICA. ON TUESDAY...EXPECT FRONTAL CONVECTION TO
DECREASE SIGNIFICANTLY. OVER THE WINDWARD ISLANDS...INDUCED TROUGH
CONVECTION WILL FAVOR 05-10MM/DAY AND MAXIMA OF 15-20MM. SIMILAR
AMOUNTS ARE EXPECTED IN HISPANIOLA. ALSO ON TUESDAY...SHEAR LINE
CONVECTION WILL FAVOR 10-15MM/DAY AND MAXIMA OF 20-45MM IN
NORTHERN GUYANA/NORTHEAST VENEZUELA. ON WEDNESDAY...SHEAR LINE
CONVECTION WILL FAVOR 05-10MM/DAY AND MAXIMA OF 15-25MM IN THE
WINDWARD ISLANDS AND NORTHEAST VENEZUELA. THE MOIST PLUME
ASSOCIATED WITH THE OLD FRONT WILL FAVOR 10-15MM/DAY AND MAXIMA OF
20-35MM.
IN NORTHERN SOUTH AMERICA AND IN THE UPPER LEVELS...ENHANCED
VENTILATION CONTINUES IN EQUATORIAL LOCATIONS...AS A ZONAL AXIS OF
THE SUBEQUATORIAL RIDGE EXTENDS FROM THE NORTHERN GUIANAS INTO
SOUTHERN CENTRAL AMERICA AND ANOTHER ZONAL AXIS OF THE BOLIVIAN
HIGH FROM CENTRAL BRASIL INTO CENTRAL PERU. THIS PATTERN IS
EXPECTED TO CONTINUE THROUGH THE CYCLE TO FAVOR PERSISTENT UPPER
DIVERGENCE THAT WILL STIMULATE NET/ITCZ CONVECTION. IN THE
LOW-LEVELS...AN INDUCED TROUGH EXTENDING ACROSS THE WINDWARD
ISLANDS INTO SOUTHERN VENEZUELA WILL BE FOCUS FOR HEAVY RAINFALL
ON MONDAY...IN INTERACTION WITH THE NET. THIS WILL FAVOR
15-30MM/DAY AND MAXIMA OF 50-100MM FROM WESTERN GUYANA ACROSS MOST
OF SOUTHEAST AND CENTRAL VENEZUELA AND INTO NORTHERN
BRASIL...INCLUDING A RISK FOR MCS FORMATION. ACROSS NORTHEAST
VENEZUELA TRINIDAD AND TOBAGO AND BARBADOS EXPECT 05-10MM/DAY AND
MAXIMA OF 15-30MM. SIMILAR AMOUNTS ARE EXPECTED IN WESTERN
VENEZUELA INTO CENTRAL COLOMBIA...AS WELL AS IN THE REST OF THE
GUIANAS. ON TUESDAY...EXPECT 15-20MM/DAY AND MAXIMA OF 40-80MM IN
SURINAME AND MOST OF GUYANA/SOUTHEAST VENEZUELA. IN CENTRAL AND
NORTHEAST VENEZUELA...AS WELL AS FRENCH GUIANA EXPECT 10-15MM/DAY
AND MAXIMA OF 20-45MM. ON WEDNESDAY...EXPECT 15-30MM/DAY AND
MAXIMA OF 40-80MM IN THE CENTRAL AND SOUTHERN GUIANAS... WHILE IN
COASTAL AREAS OF SURINAME AND GUYANA...INTO MOST OF SOUTHEAST
VENEZUELA EXPECT 10-15MM/DAY AND MAXIMA OF 20-35MM. IN WESTERN
PORTIONS OF THE CONTINENT...EXPECT A PEAK IN PRECIPITATION ON
TUESDAY...WHEN MOISTURE CONVERGENCE ALONG EASTERN PORTIONS OF THE
ANDEAN RANGE IN COLOMBIA WILL FAVOR 15-20MM/DAY AND MAXIMA OF
25-50MM. IN THE PACIFIC BASIN OF ECUADOR AND NORTHERN PERU EXPECT
SIMILAR AMOUNTS. ON WEDNESDAY...EXPECT 10-15MM/DAY AND MAXIMA OF
20-35MM IN MOST OF COLOMBIA...WHILE IN ECUADOR EXPECT MAXIMA UNDER
15-25MM.
GALVEZ/ACOSTA...WPC (USA)
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