753
FXCA20 KWBC 281818
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
218 PM EDT FRI APR 28 2023
FORECAST BULLETIN FROM 28 APR 2023 AT 1815 UTC: A SURFACE FRONT IS
MOVING ACROSS SOUTH TEXAS INTO THE NORTHERN GULF OF MEXICO. BY
FRIDAY...A LOW PRESSURE IS EXPECTED ACROSS THE SOUTHERN PLAINS OF
THE USA...CREATING A SURFACE COLD FRONT... WHICH IS FORECAST TO
EXTEND ACROSS CENTRAL TEXAS INTO NORTHERN COAHUILA/NORTHERN
CHIHUAHUA BY SATURDAY EVENING. BY SUNDAY MORNING...THE FRONT IS
EXPECTED ACROSS EASTERN MISSISSIPPI...JUST NORTHWEST OF THE
YUCATAN PENINSULA...INTO CENTRAL VERACRUZ. NOTE THAT THIS FRONT
WILL ARRIVE WITH A POTENT LATE-SEASON NORTES EVENT...THAT COULD
DEVELOP A TEHUANTEPECER LOW-LEVEL JET DURING THE DAY ON SUNDAY.
WINDS ARE FORECAST TO PEAK AT 40-45KT DURING SUNDAY AFTERNOON.
THEN BY MONDAY MORNING...ANOTHER COLD FRONT WILL BE PRESENT OVER
SOUTHERN MISSISSIPPI...EAST INTO NORTHERN FLORIDA...WHILE THE
FRONT THAT WILL BE OVER SOUTHERN MEXICO WILL MOVE SOUTH EVEN
MORE...REACHING GUATEMALA AND BELIZE. IN TERMS OF RAINFALL...ON
FRIDAY...LATE EVENING FRONTAL CONVECTION WILL FAVOR 05-10MM/DAY
AND ISOLATED MAXIMA OF 15MM ALONG THE RIO BRAVO IN NORTHEASTERN
MEXICO. HOWEVER...A SMALL AREA OF CHIAPAS COULD HAVE ISOLATED
STRONG STORMS...THAT COULD LEAVE 15-20MM WITH MAXIMA BETWEEN
25-50MM. ON SATURDAY...EXPECT OROGRAPHIC ENHANCEMENT ONCE AGAIN TO
FAVOR 15-20MM AND MAXIMA OF 30-60MM IN NORTHERN CHIAPAS AND
SOUTHEAST VERACRUZ. IN TABASCO/CENTRAL AND NORTHERN GUATEMALA AND
SOUTHERN BELIZE EXPECT 15-20MM/DAY AND MAXIMA OF 40-80MM WITH A
RISK FOR MCS FORMATION. EVENING THUNDERSTORMS IN THE YUCATAN
PENINSULA WILL FAVOR 05-10MM/DAY AND MAXIMA OF 15-25MM. VERY
LITTLE TO NO RAIN IS EXPECTED OVER MEXICO ON SUNDAY INTO
MONDAY...WITH SIGNIFICANT RAINFALL FORECAST ONLY FOR A SMALL
SECTION OF CHIAPAS...HAVING 10-15MM WITH MAXIMA OF 20-35MM.
IN CENTRAL AMERICA...DIURNAL CONVECTION IS EXPECTED ON A DAILY
BASIS FROM CENTRAL AND SOUTHERN GUATEMALA INTO SOUTHERN
HONDURAS/EL SALVADOR ALONG THE CONTINENTAL DIVIDE...AND ALSO
ACROSS THE PACIFIC SIDE OF COSTA RICA AND PANAMA. EXPECT ISOLATED
DEVELOPMENT WHILE THE REGION LIES UNDER THE INFLUENCE OF A
MID-LEVEL RIDGE TODAY. HOWEVER...PREFRONTAL CONVECTION ON SATURDAY
WILL FAVOR AN INCREASE IN RAINFALL ACTIVITY ACROSS HONDURAS...EL
SALVADOR AND SOUTHERN GUATEMALA TO 05-10MM/DAY AND MAXIMA OF
15-35MM. A GRADUAL INCREASE IN AVAILABLE MOISTURE WILL ALSO CAUSE
AN INCREASE IN RAINFALL ACCUMULATIONS ACROSS THE SAME PACIFIC
SECTIONS OF COSTA RICA AND THE AZUERO REGION OF PANAMA...CAUSING
05-10MM/DAY AND ISOLATED MAXIMA OF 15-25MM IN EASTERN PANAMA...BUT
UP TO 35MM ACROSS WESTERN PANAMA AND ACROSS COSTA RICA. FOR SUNDAY
INTO MONDAY...THE DAILY RAINFALL ACCUMULATIONS FOR COSTA RICA AND
PANAMA WILL BE AROUND 05-10MM WITH MAXIMA BETWEEN 15-25MM.
ACROSS THE CARIBBEAN...MODEL GUIDANCE INSIST ON THE STRENGTHENING
OF A MID-LEVEL RIDGE...WHICH HAS ESTABLISHED OVER THE CENTRAL
CARIBBEAN/NORTH OF THE GUAJIRA PENINSULA TODAY. THIS RIDGE COULD
PERSIST FOR THE NEXT SEVERAL DAYS WHILE MEANDERING NORTHEASTWARD
INTO PUERTO RICO AND HISPANIOLA BY SUNDAY/MONDAY. THIS WOULD
GENERALLY FAVOR FAIR WEATHER CONDITIONS...ESPECIALLY IN
COMBINATION WITH AN UPPER CONVERGENT SIGNATURE OF THE
MJO...LEADING TO WIDELY ISOLATED COVERAGE OF PRECIPITATING
CONVECTION. HOWEVER...LOCALLY INDUCED SHOWER ACTIVITY COULD CAUSE
ISOLATED SECTIONS OF PUERTO RICO AND HISPANIOLA TO OBSERVE AS MUCH
AS 25MM ACROSS THE HIGHER ELEVATIONS. WETTER CONDITIONS WILL
CONTINUE TO CLUSTER IN PORTIONS OF THE LESSER ANTILLES IN
ASSOCIATION WITH AN ILL-DEFINED SHEAR LINE STRUCTURE. THIS WILL
FAVOR 05-10MM/DAY AND MAXIMA OF 15MM TODAY...DECREASING TO
00-05MM/DAY AND MAXIMA OF 10MM FOR SATURDAY AND SUNDAY.
ACROSS SOUTH AMERICA...THE AVAILABLE MOISTURE WILL BE IN THE RANGE
OF 50-55MM ACROSS THE NORTHWEST AMAZON/ORINOQUIA INTO THE WEST
AND NORTHWEST OVER NORTHERN PERU...VENEZUELA AND COLOMBIA. THIS
MOISTURE WILL ALLOW FOR A WIDE AREA OF COLOMBIA AND WESTERN
VENEZUELA TO OBSERVE 15-20MM OF RAIN WITH MAXIMA OF
25-50MM...WHILE WESTERN ECUADOR AND SOUTHWESTERN COLOMBIA...EXPECT
15-30MM/DAY AND MAXIMA OF 50-100MM AIDED BY ENHANCED ONSHORE FLOW.
ON SATURDAY...THE RELATIVELY DEEP AVAILABLE MOISTURE...AS WELL AS
SHORT WAVES IN THE TRADES APPROACHING FROM THE EAST...WILL FAVOR
SCATTERED MODERATE SHOWERS AND ISOLATED THUNDERSTORMS OVER CENTRAL
AND WESTERN COLOMBIA AND IN THE WESTERN ORINOQUIA...WHERE AMOUNTS
ARE FORECAST TO REACH 15-20MM/DAY AND MAXIMA OF 30-60MM. IN
NORTHWEST VENEZUELA/NORTHERN COLOMBIA EXPECT 10-15MM/DAY AND
MAXIMA OF 20-35MM WHILE IN SOUTHERN COLOMBIA...MOST OF ECUADOR AND
NORTHWEST BRAZIL EXPECT 10-15MM/DAY AND MAXIMA OF 20-45MM. FOR
SUNDAY...THE HIGHEST AMOUNTS OF RAIN ARE EXPECTED WEST OF THE
CORDILLERA ALONG COLOMBIA AND ECUADOR. 15-20MM WITH MAXIMA OF
30-70MM EXPECTED FOR WESTERN COLOMBIA...WHILE MAX OF 30-60MM ARE
EXPECTED FOR WESTERN ECUADOR AND SOUTHWESTERN COLOMBIA. THE REST
OF COLOMBIA...EASTERN ECUADOR...NORTHERN PERU AND WESTERN
VENEZUELA COULD OBSERVE 05-10MM WITH MAXIMA OF 15-25MM. NORTHERN
BRAZIL COULD OBSERVE 10-15MM WITH MAXIMA OF 20-35MM.
ALAMO/ACOSTA/GALVEZ...WPC (USA)
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