150
FXCA20 KWBC 171855
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
255 PM EDT MON APR 17 2023
FORECAST BULLETIN FROM 17 APR 2023 AT 1830 UTC: A SURFACE HIGH
PRESSURE ACROSS THE ATLANTIC IS PROMOTING EASTERLY WINDS ACROSS
THE CARIBBEAN...AND SOUTHEASTERLY WINDS ACROSS THE WESTERN GULF OF
MEXICO. A WEAK SURFACE LOW PRESSURE IS DEVELOPING ACROSS THE
EASTERN PACIFIC...JUST NORTH OF THE GALAPAGOS ISLANDS. THIS IS
CAUSING WEAK WINDS ACROSS THE AREA AND WOULD ALLOW FOR DIURNAL
ONSHORE WIND FLOW ACROSS THE WEST COAST OF NORTHERN SOUTH AMERICA
OVER THE NEXT FEW DAYS. ONSHORE WIND FLOW WILL ALSO OCCUR ACROSS
THE NORTH COAST OF SOUTH AMERICA...AND ACROSS CENTRAL AMERICA THE
WINDS WILL COME FROM THE CARIBBEAN SIDE. AN UPPER TROUGH EXTENDS
DOWN AND ACROSS THE GULF OF MEXICO...THEN AN UPPER RIDGE IS
PRESENT OVER THE WESTERN ATLANTIC. THIS IS MOVING EAST...AND THE
UPPER TROUGH WILL BE IN THE WEST ATLANTIC BY WEDNESDAY. THERE IS
ALSO A WEAK MID LEVEL TROUGH ACROSS THE EASTERN GULF OF MEXICO
THAT CONTINUES TO WEAKEN AS IT MOVES SLOWLY TO THE EAST...AS IT IS
ASSOCIATED WITH A MID LEVEL LOW PRESSURE MOVING NORTHEAST ACROSS
THE EAST AND NORTHEASTERN US. THE UPPER TROUGH COMBINED WITH
ONSHORE WIND FLOW WILL CAUSE THE DEVELOPMENT OF SHOWERS AND
ISOLATED THUNDERSTORMS ACROSS EASTERN TO SOUTHERN MEXICO TODAY.
THE SOUTHERN STATES OF MEXICO AND THE BORDER WITH GUATEMALA HAS
THE HIGHEST EGDI ALGORITHM OUTPUT TODAY...AND THE RAINFALL
FORECAST HAS MAXIMA OF 20-35MM FROM CHIAPAS TO GUATEMALA AND EL
SALVADOR TODAY. FOR TUESDAY AND WEDNESDAY THE RAINFALL COVERAGE
AND AMOUNTS WILL BE MUCH LESS...WITH 05-10MM AND MAXIMA OF 15MM.
ACROSS THE ATLANTIC...THERE IS ALSO A A COLD FRONT THAT EXTENDS
FROM THE CENTRAL ATLANTIC...TO THE SOUTHWEST ACROSS THE NORTHERN
BAHAMAS...WESTERN CUBA AND INTO THE YUCATAN PENINSULA. THIS FRONT
WILL BECOME STATIONARY IN ITS WESTERNMOST END...BUT THE COLD FRONT
WILL CONTINUE TO SLOWLY PUSH SOUTH ACROSS THE BAHAMAS ON TUESDAY
AND WEDNESDAY AS IT WEAKENS. AHEAD IF THE FRONT THERE IS A SURFACE
TROUGH THAT WILL COMBINE WITH THE DIVERGENT SIDE OF THE MID LEVEL
TROUGH...TO CAUSE SHOWERS AND THUNDERSTORMS ACROSS THE BAHAMAS
TODAY AND THROUGH THE FIRST HALF OF THE WORKWEEK. THE NORTHERN
BAHAMAS WILL HAVE THE HIGHEST AMOUNTS OF RAINFALL TODAY WITH
TOTALS FORECAST AT 10-15MM AND MAX OF 20-40MM...WHILE THE SOUTHERN
HALF WILL OBSERVE UP TO 10MM OF RAIN TODAY. ON TUESDAY AND
WEDNESDAY...THE BAHAMAS AS A WHOLE IS FORECAST TO OBSERVE MAXIMA
OF 15-25MM BUT A SMALL SECTION OF THE CENTRAL BAHAMAS COULD HAVE
SQUALLY WEATHER AND OBSERVE 20-30MM ON TUESDAY.
DUE TO THE AFOREMENTIONED UPPER TROUGH...COMBINED WITH THE ONSHORE
WIND FLOW AND AVAILABLE MOISTURE...THE NORTHERN COUNTRIES OF
CENTRAL AMERICA COULD RECEIVE 20-35MM OF RAIN TODAY...WHILE
RELATIVELY SMALL AMOUNTS OF RAIN ARE EXPECTED ACROSS NICARAGUA AND
HONDURAS...UP TO 10MM. COSTA RICA AND PANAMA IS FORECAST TO
OBSERVE 05-10MM WITH MAXIMA UP TO 25MM TODAY. AS THE IMPACT OF THE
UPPER TROUGH MOVES EAST...THE RAINFALL TOTALS ACROSS CENTRAL
AMERICA WILL DIMINISH FOR TUESDAY AND WEDNESDAY...TOTALS RANGING
FROM 00-05MM AND MAX OF 10MM ACROSS ISOLATED AREAS OF CENTRAL
AMERICA..WITH THE EXCEPTION OF EL SALVADOR AND SOUTHERN
GUATEMALA...WHERE 15-20MM IS POSSIBLE ON TUESDAY.
THE CARIBBEAN IS EXPECTED TO REMAIN SOMEWHAT UNSETTLED. THERE IS A
MID LEVEL RIDGE ACROSS THE EASTERN CARIBBEAN THAT IS EXPECTED TO
KEEP DEEP CONVECTION AT BAY. HOWEVER...NEAR NORMAL MOISTURE AND
SOME TROUGHINESS ACROSS THE NORTHWESTERN CARIBBEAN ISLANDS WILL
COMBINE WITH THE ISLAND DIURNAL EFFECTS...CAUSING MAXIMAS UP TO
15-25MM ACROSS PUERTO RICO AND THE DOMINICAN REPUBLIC
TODAY...WHILE HAITI AND WESTERN CUBA COULD SEE UP TO 40MM ACROSS
ISOLATED AREAS. AS THE MID LEVEL TROUGH MOVES EAST...AND ALSO THE
UPPER TROUGH APPROACHING THE AREA...THE CHANCE OF SQUALLY WEATHER
AND HIGHER AMOUNTS OF RAIN INCREASES. ON TUESDAY...HISPANIOLA
COULD OBSERVE 15-20MM WITH MAX OF 25-50MM...WHILE THE REST OF THE
CARIBBEAN ISLANDS WOULD OBSERVE MAXIMA UP TO 15-20MM.
IN SOUTH AMERICA...THERE WILL BE RELIABLE CONVECTION ALONG THE
NET...BUT THE AMOUNTS OF RAIN WILL NOT BE THE HIGHEST IN THE AREA.
FOR THE MOST PART...DAILY RAINFALL WILL BE IN THE ORDER OF 05-10MM
WITH MAXIMA OF 15-35MM ACROSS THE MAJORITY OF OF NORTHERN SOUTH
AMERICA. THE EXCEPTIONS ARE PORTIONS OF THE GUIANAS...AND NORTHERN
COLOMBIA...WHERE HIGHER AMOUNTS OF RAIN ACROSS THE GUIANAS ARE
EXPECTED...NEAR 15-20MM AND MAXIMA OF 40-80MM TODAY...WHILE
NORTHERN COLOMBIA AND WESTERN VENEZUELA COULD OBSERVE 15-20MM WITH
MAXIMA OF 25-50MM. THE RAINFALL FORECAST LOOKS VERY SIMILAR FOR
TUESDAY WITH SLIGHTLY LESS RAIN OVER NORTHERN COLOMBIA. HOWEVER
ACROSS PORTIONS OF NORTHERN PERU ON TUESDAY AND
WEDNESDAY...RAINFALL TOTALS COULD REACH 15-20MM WITH MAXIMA OF
40-80MM.
ALAMO/ACOSTA...WPC (USA)
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