009
FXCA20 KWBC 311721
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
121 PM EDT MON JUL 31 2023
FORECAST BULLETIN FROM 31 JUL 2023 AT 1730 UTC: WHILE THE
SUBTROPICAL UPPER RIDGE MEANDERS THE SOUTHWEST AND SOUTH-CENTRAL
US...A TRAIN OF TUTTS AND RIDGES IS FORECAST TO CONTINUE
RETROGRADING WESTWARD IN AREAS TO THE SOUTH. THESE WILL INTERACT
WITH TROPICAL WAVES PROPAGATING ALONG NROTHERN CENTRAL AMERICA AND
MEXICO TO ENHANCE DIURNAL CONVECTION. ON MONDAY...THE LARGEST
AMOUNTS IN MEXICO ARE EXPECTED IN WESTERN OAXACA WHERE
AFTERNOON-EVENING LOW-LEVEL MOISTURE CONVERGENCE WILL TRIGGER
MAXIMA OF 25-50MM...AIDED ALSO BY VENTILATION IN THE SOUTHEAST
PERIPHERY OF AN UPPER RIDGE. AREAS WEST SHOULD EXPECT MAXIMA OF
15-30MM IN DIURNAL CONVECTION. ON TUESDAY...ONSHORE FLOW IN
OAXACA/GUERRERO WILL FAVOR SIMILAR ACCUMULATIONS...WHILE A
TROPICAL WAVE ENTERING CAMPECHE/CHIAPAS/TABASCO FAVORS MAXIMA OF
35-70MM IN THESE REGIONS. ON WEDNESDAY EXPECT MAXIMA OF 25-50MM IN
OAXACA/GUERRERO/MICHOACAN WITH THE TROPICAL WAVE. TRAILING
MOISTURE WILL FAVOR MAXIMA OF 20-45MM FROM GUATEMALA INTO SOUTHERN
VERACRUZ.
IN THE CARIBBEAN...A TUTT CENTERING OVER THE NORTHWEST BAHAMAS IS
FORECAST TO RETROGRADE TO CENTER OVER VERACRUZ BY WEDNESDAY
EVENING. AN UPPER TROUGH ACROSS THE EASTERN USA IS FORECAST TO
EXTEND ITS BASE INTO THE NORTHWEST BAHAMAS THROUGH MOST OF THE
CYCLE...WHICH WILL FAVOR DEEP CONVECTION ON A DAILY BASIS...YET
COVERAGE IS NOT EXPECTED TO BE GENERALIZED. AREAS TO THE EAST WULL
BE UNDER THE INFLUENCE OF AN UPPER RIDGE FORECAST TO MEANDER FROM
THE EASTERN CARIBBEAN INTO THE CENTRAL CARIBBEAN THROUGH THE
FORECAST CYCLE. IN THE LOWER LEVELS...AVAILABLE MOISTURE IS
ORGANIZING ALONG A LOW-LEVEL TROUGH THAT EXTENDS FROMT HE CENTRAL
CARIBBEAN ACROSS THE LEEWARD ISLANDS INTO A SURFACE LOW LOCATED
OVER THE TROPICAL NORTH ATLANTIC. THIS TROUGH IS PROPAGATING
NORTHWESTWARD...AND WILL FAVOR MAXIMA OF 20-35MM IN THE LEEWARD
ISLANDS...VI AND SOUTHEAST PUERTO RICO ON MONDAY. ON TUESDAY THE
MOIST PLUME IS FORECAST TO MEANDER INTO HISPANIOLA WHERE IT WILL
FAVOR 10-15MM/DAY AND MAXIMA OF 20-35MM...TO THEN LOOSE
DEFINITION. ON WEDNESDAY...A TROUGH IN THE TRADES ARRIVES IN THE
ARC OF THE LESSER ANTILLES TO FAVOR MAXIMA GENERALLY UNDER
15MM/DAY. DIURNAL COVNECTION WILL PEAK IN EAST CUBA AND
HISPANIOLA...WHERE EXPECT MAXIMA OF 15-25MM.
WET CONDITIONS ARE EXPECTED IN PORTIONS OF CENTRAL AMERICA AS TWO
TROPICAL WAVES MOVE ACROSS THE REGION...ACCOMPANIED BY A
NOTICEABLE INCREASE IN PRECIPITABLE WATER AS THEY MOVE THROUGH
(SEE BELOW FOR AMOUNTS). INITIALLY...EXPECT POSITIVE INTERACTION
IN WEST PANAMA AND SOUTHERN COSTA RICA AS THE BASE OF AN UPEPR
TROUGH AND A TROPCIAL WAVE INTERACT. THIS WILL FAVOR MAXIMA OF
40-80MM AND A RISK FOR MCS FORMATION THROUGH EARLY TUESDAY. ON
TUESDAY...EXPECT THE MOIST POOL TO EXTEND FROM CENTRAL COSTA RICA
INTO SOUTHEAST MEXICO. THIS WILL FAVOR SCATTERED MAXIMA OF 20-45MM
FROM CENTRAL COSTA RICA INTO BELIZE/SOUTHERN GUATEMALA. HIGHER
AMOUNTS ARE EXPECTED IN NORTHEAST NICARAGUA/EASTERN HONDURAS AND
NORTHERN GUATEMALA DUE TO ENHANCED MOISTURE CONVERGENCE. ON
WEDNESDAY...EXPECT THE MOIST POOL FROM NORTHERN NICARAGUA INTO
SOUTHERN MEXICO. EXPECT GENERAL MAXIMA OF 20-45MM...ALTHOUGH THE
DISTRIBUTION OF DIURNAL CONVECTION IS OF LIMITED CONFIDENCE.
IN NORTHERN SOUTH AMERICA...EXPECT A GENERAL DECREASING TREND
GIVEN A DECREASE IN AVAILABLE MOISTURE THROUGH THE CYCLE. THE
LARGEST ACCUMULATIONS ARE EXPECTED IN NORTHERN COLOMBIA/WEST
VENEZUELA EARLY IN THE CYCLE AND IN ASSOCIATION WITH A TROPICAL
WAVE...WHICH WILL FAVOR MAXIMA OF 25-50MM. THIS DECREASES
GRADUALLY TO MAXIMA OF 15-25MM BY WEDNESDAY.
POSITIONS OF TROPICAL/EASTERLY WAVES INITIALIZED AT 12 UTC
TYPE SOF INIT 01/00 01/12 02/00 02/12 03/00 03/12 04/00 04/12
TW 18N 35W 38W 41W 44W 48W 52W 56W 60W 64W
TW 20N 68W 72W 75W 78W 81W 84W 87W 90W 93W
TW 22N 80W 83W 87W 92W 95W 98W 102W 105W 107W
TW 26N 104W 106W 108W 111W 114W EXITS
A TROPICAL WAVE IS INITIALIZED AT 35W AND SOUTH OF 18N. IT WILL
ENTER THE GUIANAS ON WEDNESDAY TO FAVOR ISOLATED MAXIMA OF 15-25MM
IN NORTHERN FRENCH GUIANA AND SURINAME.
A TROPICAL WAVE IS INITIALIZED AT 68W AND SOUTH OF 20N. ON MONDAY
IT WILL FAVOR MAXIMA 25-50MM IN NORTHERN COLOMBIA/NORTHWEST
VENEZUELA...AND MAXIMA OF 15-25MM IN HISPANIOLA. ON TUESDAY IT
WILL FAVOR MAXIMA OF 20-35MM IN PANAMA AND NORTHWEST
COLOMBIA...AND MAXIMA OF 15-20MM IN SOUTHEAST CUBA AND IN JAMAICA.
ON WEDNESDAY IT WILL FAVOR MAXIMA OF 20-45MM IN HONDURAS/NORTH
NICARAGUA AND MAXIMA OF 15-25MM IN SOUTHERN NICARAGUA...COSTA RICA
AND WEST PANAMA.
A TROPICAL WAVE IS INITIALIZED AT 80W AND SOUTH OF 22N. ON MONDAY
IT WILL FAVOR MAXIMA OF 40-80MM IN PANAMA AND SOUTHERN COSTA RICA
WITH A RISK FOR MCS FORMATION. IN EAST NICARAGUA/EAST HONDURAS
EXPECT MAXIMA OF 15-25MM. ON TUESDAY IT WILL FAVOR MAXIMA OF
35-70MM IN CHIAPAS/TABASCO/CAMPECHE/NORTH GUATEMALA...AND MAXIMA
OF 20-35MM IN SOUTHERN GUATEMALA/SOUTHERN CHIAPAS. ON
WEDNESDAY...IT WILL FAVOR MAXIMA OF 25-50MM IN OAXACA AND GUERRERO
IN SOUTHERN MEXICO.
A TROPICAL WAVE IS INITIALIZED AT 104W AND SOUTH OF 26N. ON MONDAY
IT WILL FAVOR MAXIMA OF 15-30MM IN WEST MEXICO. ON
TUESDAY...TRAILING MOISTURE WILL FAVOR MAXIMA OF 15-30MM ALONG THE
SIERRA MADRE OCCIDENTAL AND ADJACENT COASTAL PLAIN. IT WILL THEN
EXIT INTO OPEN WATERS OF THE PACIFIC.
GALVEZ...WPC (USA)
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