254
FXCA20 KWBC 011653
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1253 PM EDT MON MAY 01 2023
FORECAST BULLETIN FROM 01 MAY 2023 AT 1800 UTC: THE MJO ANALYSIS
SHOWS ENHANCED UPPER CONVERGENCE EXTENDING OVER MOST OF THE
AMERICAS...AS THE MJO PROPAGATES ALONG PHASES 4 AND 5. UPPER
CONVERGENCE IS FORECAST TO PERSIST THROUGH THE WORK
WEEK...RESULTING IN REDUCED COVERAGE OF AREAS OF STRONGEST
CONVECTION AND HEAVIEST PRECIPITATION. FURTHERMORE...THE UPPER
CONVERGENT PHASE ASSOCIATED WITH A STRENGTHENING OF THE EASTERLY
TRADES...WHICH IS BEING RESOLVED BY MODELS INTO THE MIDDLE AND
LATER PART OF THE WORK WEEK.
NORTHWEST IN THE DOMAIN...A BROAD UPPER TROUGH EXTENDS OVER
CALIFORNIA/EXTREME NORTHWEST MEXICO. THE TROUGH IS MOVING
LITTLE...YET SHORT WAVE VORTICES ARE PROPAGATING NORTHEASTWARD
ALONG ITS SOUTHERN PERIPHERY. ON MONDAY...ONE OF THESE VORTICES IS
EXPECTED TO CROSS THE SIERRA MADRE OCCIDENTAL IN NORTHWEST MEXICO
TO PRODUCE VERY LIGHT PRECIPITATION. THE NEXT SHORT WAVE TROUGH OF
INTEREST APPROACHES MEXICO FROM THE WEST ON WEDNESDAY. THIS WILL
AID TO SOME EXTENT THE ONSHORE INFLUX OF MOISTURE FROM THE GULF OF
MEXICO...TO FAVOR ISOLATED THUNDERSTORMS IN INTERIOR PORTIONS OF
NORTHEAST MEXICO...WHERE EXPECT 05-10MM/DAY AND ISOLATED MAXIMA OF
15MM WITH A SLIGHT RISK OF SEVERITY.
TO THE EAST AND IN THE MID-LEVELS...A RIDGE CENTERS OVER PUERTO
RICO AND EXTENDS ACROSS MOST OF THE EASTERN CARIBBEAN INTO THE
SOUTHEAST BAHAMAS AND SOUTHEAST CUBA. IN THE LOW-LEVELS...A FRONT
IS WEAKENING ACROSS THE CENTRAL BAHAMAS/CENTRAL CUBA AND JUST
NORTH OF THE CAYMAN ISLANDS ON MONDAY. THE FRONT IS FORECAST TO
MOVE LITTLE THROUGH TUESDAY...AND BY TUESDAY EVENING IT IS
FORECAST AS A STATIONARY BOUNDARY ACROSS THE CENTRAL
BAHAMAS...NORTH CENTRAL CUBA. BY WEDNESDAY IT IS FORECAST TO LOOSE
DEFINITION WHILE MEANDERING NORTHWESTWARD ACROSS THE NORTHWEST
BAHAMAS. INITIALLY...ISOLATED DEEP CONVECTION WILL STILL BE
FAVORED AS THE BOUNDARY REMAINS IN THE NORTHWEST PERIPHERY OF THE
MID-LEVEL RIDGE. THROUGH EARLY TUESDAY...EXPECT 05-10MM/DAY AND
MAXIMA OF 15-30MM IN CENTRAL CUBA...WHILE IN THE CENTRAL BAHAMAS
EXPECT 05-10MM/DAY AND MAXIMA OF 15-20MM. ON TUESDAY...ZONAL FLOW
ESTABLISHES IN THE MID-LEVELS AS THE RIDGE EXPANDS NORTHWARD. THIS
WILL FAVOR A DECREASE IN ACCUMULATION TO 05-10MM/DAY AND MAXIMA OF
15MM IN MOST OF CUBA AND THE CENTRAL BAHAMAS. BY
WEDNESDAY...EXPECT SIMILAR AMOUNTS IN THE NORTHWEST BAHAMAS
ASSOCIATED WITH THE WEAKENING PLUME. IN SOUTHEAST CUBA...AND
APPROACHING SHORT WAVE TROUGH WILL STIMULATE THUNDERSTORM
DEVELOPMENT TO FAVOR 05-10MM/DAY AND MAXIMA OF 15-25MM. ELSEWHERE
IN THE ANTILLES...EXPECT LITTLE PRECIPITATION THROUGH THE CYCLE AS
THE REGION REMAINS UNDER THE INFLUENCE OF THE MID-LEVEL RIDGE.
DIURNAL CONVECTION IS STILL EXPECTED ON A DAILY BASIS IN
HISPANIOLA AND PUERTO RICO...WHERE EXPECT 05-10MM/DAY AND VERY
ISOLATED MAXIMA OF 15-20MM OR LESS. LIGHT RAIN SHOWERS ARE ALSO
EXPECTED IN THE CENTRAL LESSER ANTILLES IN ASSOCIATION WITH A
MOIST PLUME MOVING IN FROM THE TROPICAL ATLANTIC.
AN EASTERLY WAVE IS PROPAGATING ACROSS THE SOUTHWEST CARIBBEAN
INTO SOUTHERN CENTRAL AMERICA. ON MONDAY...THIS WILL HIGHLIGHT
PRECIPITATION IN WESTERN PANAMA...COSTA RICA AND NICARAGUA. EXPECT
THE LARGEST ACCUMULATIONS IN SOUTHEAST NICARAGUA AND NORTHEAST
COSTA RICA...AIDED BY TRADE WIND CONVERGENCE. THIS WILL FAVOR
15-20MM/DAY AND MAXIMA OF 25-50MM. ELSEWHERE IN COSTA RICA AND IN
WESTERN PANAMA EXPECT 10-15MM/DAY AND MAXIMA OF 20-35MM. ALSO ON
MONDAY...ENHANCED INSTABILITY AND A SURFACE TROUGH WILL FAVOR
AFTERNOON THUNDERSTORMS FROM SOUTHERN HONDURAS/EL SALVADOR INTO
SOUTHERN GUATEMALA...WHERE EXPECT 10-15MM/DAY AND MAXIMA OF
20-35MM. ON TUESDAY...THE EASTERLY WAVE IS EXPECTED TO CROSS COSTA
RICA AND NICARAGUA...TO FAVOR 10-15MM/DAY AND MAXIMA OF 20-35MM
FROM NORTHWEST PANAMA INTO ALL OF EASTERN NICARAGUA AND MOST OF
COSTA RICA. DIURNAL CONVECTION IN HONDURAS/EL SALVADOR AND
GUATEMALA/CHIAPAS WILL FAVOR 10-15MM/DAY AND MAXIMA OF 20-45MM. ON
WEDNESDAY...THE EASTERLY WAVE IS EXPECTED TO PROPAGATE ACROSS
WESTERN HONDURAS/EL SALVADOR INTO GUATEMALA. A DECREASE IN
AVAILABLE MOISTURE AND ACCELERATION OF THE EASTERLY TRADES SHOULD
FAVOR A DECREASE IN ACCUMULATION TO 05-10MM/DAY AND MAXIMA OF
15-25MM FROM CENTRAL HONDURAS INTO MOST OF GUATEMALA AND SOUTHERN
BELIZE. IN COSTA RICA AND WESTERN PANAMA EXPECT 05-10MM/DAY AND
MAXIMA OF 15-20MM.
A DRY SPELL IS ESTABLISHING IN NORTHERN SOUTH AMERICA IN
ASSOCIATION WITH AN ACCELERATION OF THE EASTERLY TRADES ACROSS THE
TROPICAL ATLANTIC AND SOUTHEAST CARIBBEAN. THESE ARE FAVORING THE
ADVECTION OF A DRIER AIR MASS LOCATED ABOVE THE MARINE LAYER INTO
NORTHEAST PORTIONS OF THE CONTINENT. THIS IS RESULTING IN A
SOUTHWARD DISPLACEMENT OF THE ATLANTIC ITCZ...WHICH IS FORECAST TO
ENTER THE CONTINENT ACROSS AMAPA DURING MOST OF THE FORECAST
CYCLE...FAVORING FAIR WEATHER CONDITIONS IN MOST OF THE GUIANAS.
THE HEAVIEST PRECIPITATION IS EXPECTED IN AMAPA AND SOUTHEAST
FRENCH GUIANA WHERE EXPECT 15-20MM/DAY AND MAXIMA 30-60MM ON
MONDAY AND WEDNESDAY. LIGHTER AMOUNTS ARE EXPECTED ON TUESDAY. IN
FRENCH GUIANA AND SURINAME EXPECT MAXIMA GENERALLY UNDER 15MM. TO
THE WEST...EXPECT A NOTICEABLE DECREASE IN PRECIPITATION IN
VENEZUELA AND NORTHERN COLOMBIA. THE LARGEST ACCUMULATIONS ARE
EXPECTED IN ECUADOR AND THE WESTERN AMAZON STARTING ON
TUESDAY...WHERE ENHANCED ONSHORE FLOW IN THE PACIFIC WILL FAVOR
10-15MM/DAY AND MAXIMA OF 20-35MM IN THE PACIFIC BASIN OF ECUADOR.
SIMILAR AMOUNTS ARE EXPECTED EAST OF THE ANDES. ON
WEDNESDAY...EXPECT AN ADDITIONAL INCREASE IN ECUADOR TO
10-15MM/DAY AND MAXIMA OF 20-45MM WHILE EAST OF THE ANDES EXPECT
10-15MM/DAY AND MAXIMA OF 20-35MM FROM NORTHERN PERU/EASTERN
ECUADOR INTO CENTRAL COLOMBIA.
GALVEZ/ACOSTA/ALAMO...WPC (USA)
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