651
FXCA20 KWBC 171652
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1252 PM EDT WED MAY 17 2023
FORECAST BULLETIN FROM 17 MAY 2023 AT 1700 UTC: A CLOSED MID-UPPER
LOW SITS JUST TO THE WEST OF NORTHERN BAJA CALIFORNIA ON
WEDNESDAY. AS A MID-UPPER RIDGE BUILDS ACROSS SOUTHERN/CENTRAL
MEXICO AND THE GULF OF MEXICO REGION THROUGH FRIDAY...THE LOW IS
FORECAST TO STALL OVER CENTRAL/NORTHERN BAJA CALIFORNIA FROM
THURSDAY THROUGH SATURDAY. ALTHOUGH THE TROUGH/LOW WILL ENHANCE
VENTILATION ACROSS CENTRAL MEXICO ON FRIDAY AS IT INTERACTS WITH
THE BUILDING RIDGE...THE ADVECTION OF DRY AIR FROM THE PACIFIC
WILL LIMIT THE COVERAGE AND INTENSITY OF DIURNAL CONVECTION. THE
BUILDING OF THE MID-LEVEL RIDGE WILL ALSO LIMIT DIURNAL CONVECTION
ON THURSDAY AND FRIDAY. HOWEVER...DIURNAL INSTABILITY WILL BE
SUFFICIENT TO BREAK THE CAP ESPECIALLY ALONG THE SIERRA MADRE
ORIENTAL AND EASTERN MEXICAN PLATEAU...TO FAVOR THUNDERSTORMS ON A
DAILY BASIS. ON WEDNESDAY...EXPECT 10-15MM/DAY AND MAXIMA OF
20-35MM IN SOUTHERN MEXICO...WHILE EXPECT ISOLATED MAXIMA OF
15-20MM IN THE NORTHERN SIERRA MADRE ORIENTAL. THE COVERAGE AND
INTENSITY DECREASES AFTER. ON THURSDAY...EXPECT 05-10MM/DAY AND
MAXIMA OF 15-20MM IN PORTIONS OF THE SIERRA MADRE ORIENTAL. ON
FRIDAY...EXPECT MOST CONVECTION TO CLUSTER IN EASTERN PORTIONS OF
THE MEXICAN PLATEAU TO PRODUCE 05-10MM/DAY AND MAXIMA OF 15-25MM.
AS A MID-LEVEL RIDGE BUILDS OVER SOUTHERN MEXICO AND CENTRAL
AMERICA THROUGH THE CYCLE...EXPECT A NOTICEABLE DRYING TREND.
EXPECT ISOLATED DIURNAL CONVECTION...AND MARGINAL ENHANCEMENT BY A
WEAK EASTERLY WAVE. EXPECT ACCUMULATIONS IN THE ORDER OF
05-10MM/DAY AND MAXIMA OF 15-20MM THROUGH THE CYCLE...PRIMARILY IN
THE FORM OF ISOLATED SHOWERS AND THUNDERSTORMS IN THE CONTINENTAL
DIVIDE AND PORTIONS OF THE PACIFIC BASIN. THE CARIBBEAN BASINS OF
COSTA RICA AND PANAMA SHOULD EXPERIENCE SCATTERED LIGHT CONVECTION
IN ASSOCIATION WITH A GRADUAL STRENGTHENING OF THE CARIBBEAN
TRADES.
THE CARIBBEAN WILL BE UNDER THE INFLUENCE OF A MID-LEVEL RIDGE
THROUGH THE CYCLE...ESPECIALLY SOUTHERN PORTIONS. THE RIDGE IS
FORECAST TO ROLL WESTWARD TOWARDS CENTRAL AMERICA INTO THE
WEEKEND...ALLOWING FOR SOME DESTABILIZATION OF THE TRADE WIND CAP
ACROSS THE GREATER ANTILLES. NEVERTHELESS...A MOIST PLUME REMAINS
IN PLACE IN THE GREATER ANTILLES AND SOUTHEAST BAHAMAS. THE AMOUNT
OF MOISTURE WILL BE SUFFICIENT TO ALLOW FOR THE DEVELOPMENT OF
STRONG DIURNAL CONVECTION ON A DAILY BASIS...ESPECIALLY IN
HISPANIOLA AND NORTHERN PUERTO RICO. THE PATTERN IS FORECAST TO
CHANGE DURING THE WEEKEND...WHEN A LARGE POLAR TROUGH IS FORECAST
TO DEEPEN ACROSS THE BAHAMAS/SOUTHEAST USA. THIS WILL START TO
ENHANCE CONVECTION ACROSS THE BAHAMAS ON FRIDAY. IN
HISPANIOLA...EXPECT AFTERNOON/EVENING CONVECTION TO PRODUCE
10-15MM/DAY AND MAXIMA OF 20-45MM ON WEDNESDAY AND
THURSDAY...INCREASING TO 15-20MM/DAY AND MAXIMA OF 25-50MM BY
FRIDAY. IN NORTHERN PUERTO RICO...EXPECT 10-15MM/DAY AND MAXIMA OF
20-35MM ON WEDNESDAY INCREASING TO 10-15MM/DAY AND MAXIMA OF
20-45MM THEREAFTER. IN JAMAICA EXPECT 05-10MM/DAY AND MAXIMA OF
15-20MM ON A DAILY BASIS. IN CUBA...EXPECT A DECREASE IN AMOUNTS
ON THURSDAY TO MAXIMA OF 15-20MM IN EASTERN PORTIONS. ON
FRIDAY...EXPECT AN INCREASING TREND TO ESTABLISH AS THE UPPER
TROUGH STARTS APPROACHING FROM THE NORTH.
IN NORTHERN SOUTH AMERICA...THE SUBEQUATORIAL RIDGE WILL BE THE
DOMINANT FEATURE...WHILE EXTENDING FROM THE GUIANAS INTO NORTHERN
COLOMBIA THROUGH THE CYCLE. SOME VARIABILITY OF PRECIPITATION WILL
BE ATTRIBUTED TO WAVES IN THE TRADES AND THE NET.
MOREOVER...ENHANCED ONSHORE FLOW IN THE PACIFIC BASIN OF ECUADOR
ON THURSDAY AND COLOMBIA ON FRIDAY WILL FAVOR LOCALLY HEAVY
RAINFALL. ON WEDNESDAY...EXPECT THE LARGEST AMOUNTS IN THE GUIANAS
WHERE ITCZ CONVERGENCE AND AN EASTERLY WAVE WILL FAVOR MAXIMA OF
30-60MM. TO THE WEST...STRONG CONVECTION FROM PREVIOUS DAYS WILL
FAVOR SOME STABILIZATION...WHICH WILL YIELD TO MORE CONSERVATIVE
AMOUNTS ON WEDNESDAY. AFTERWARDS...EXPECT ONCE AGAIN AN INCREASING
TREND IN AREAS WEST...YIELDING TO THE MOST ACTIVE CONVECTION IN
COLOMBIA...ECUADOR AND SOUTHERN VENEZUELA BY FRIDAY.
POSITIONS OF TROPICAL/EASTERLY WAVES INITIALIZED AT 12 UTC
TYPE SOF INIT 18/00 18/12 19/00 19/12 20/00 20/12 21/00
EW 11N 56W 59W 61W 63W 65W 68W 70W 73W
TW 13N 68W 72W 74W 77W 79W 80W 81W 83W
EW 18N 85W 86W 87W 89W 91W 92W 94W DISS
TW 17N 110W 113W EXITS
AN EASTERLY WAVE IS INITIALIZED AT 56W AND SOUTH OF 11N. BY
WEDNESDAY EVENING IT WILL MOVE WEST OVER CENTRAL GUYANA TO FAVOR
MAXIMA OF 30-60MM OVER MOST OF GUYANA AND SURINAME. WHILE IN
NORTHERN GUYANA AND EASTERN VENEZUELA EXPECT MAXIMA OF 20-45MM. BY
THURSDAY...THE WAVE IS FORECAST OVER EASTERN VENEZUELA. IT WILL
FAVOR MAXIMA OF 20-35MM OVER SOUTHEASTERN VENEZUELA AND
RORAIMA...WHILE IN NORTHEASTERN VENEZUELA EXPECT MAXIMA OF 15MM.
ON FRIDAY...THE WAVE IS EXPECTED OVER EASTERN COLOMBIA/SOUTHERN
VENEZUELA AND WESTERN AMAZONAS-BRASIL...WHERE IT WILL FAVOR
10-15MM/DAY AND MAXIMA OF 20-45MM.
A TROPICAL WAVE IS INITIALIZED AT 68W AND SOUTH OF 13N. ON
WEDNESDAY IT WILL FAVOR 05-10MM/DAY AND ISOLATED MAXIMA OF 15-25MM
IN WESTERN VENEZUELA AND EASTERN AND CENTRAL COLOMBIA. ON
THURSDAY...THE WAVE IS FORECAST ACROSS THE ANDEAN REGION AND
PACIFIC BASINS OF COLOMBIA AND ECUADOR. IN COMBINATION WITH
ENHANCED ONSHORE FLOW...EXPECT MAXIMA INCREASING TO 50-100MM IN
NORTHERN ECUADOR AND SOUTHWEST COLOMBIA...WHILE OTHER AREAS SHOULD
EXPECT 10-15MM/DAY AND MAXIMA OF 20-45MM. ON FRIDAY...THE WAVE IS
EXPECTED TO START BECOMING ILL-DEFINED AS IT PROPAGATES ACROSS
PANAMA. IT WILL FAVOR ISOLATED MAXIMA OF 15-20MM IN WESTERN
PANAMA/EASTERN COSTA RICA.
AN EASTERLY WAVE IS INITIALIZED AT 85W AND SOUTH OF 18N. ON
WEDNESDAY IT WILL FAVOR MAXIMA OF 15-20MM IN WESTERN
NICARAGUA/SOUTHERN HONDURAS AND NORTHERN EL SALVADOR. ON
THURSDAY...IT IS EXPECTED ACROSS EL
SALVADOR/BELIZE/GUATEMALA...WHERE IT WILL FAVOR MAXIMA OF 15-20MM
IN VERY ISOLATED CONVECTION. ON FRIDAY...THE WEAKENING WAVE WILL
FAVOR ISOLATED MAXIMA OF 15-25MM IN SOUTHERN GUATEMALA. BUT UNDER
THE INFLUENCE OF A BUILDING MID-LEVEL RIDGE ACROSS NORTHERN
CENTRAL AMERICA/SOUTHERN MEXICO AS WELL AS A DRY AIR MASS IN THE
REGION...EXPECT VERY LIMITED CONVECTIVE DEVELOPMENT ELSEWHERE.
A TROPICAL WAVE IS INITIALIZED AT 102W AND TO THE SOUTH OF 17N AND
IS FORECAST TO CONTINUE PROPAGATING OVER OPEN WATERS OF THE
PACIFIC OCEAN...WITH LIMITED EFFECTS ON CONTINENTAL REGIONS.
GALVEZ/ACOSTA...WPC (USA)
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