721
FXCA20 KWBC 271846
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
245 PM EDT TUE JUN 27 2023
FORECAST BULLETIN FROM 27 JUN 2023 AT 1900 UTC: THE UPPER PATTERN
IN MEXICO CONTINUES EVOLVING AS THE UPPER RIDGE MEANDERS NORTHWEST
INTO THE GULF OF MEXICO. THIS IS ALLOWING FOR VENTILATION ALONG
SOUTHERN/SOUTHWEST MEXICO...AND A NORTHWARD PROGRESSION OF THE
MOIST PLUMES ASSOCIATED WITH TROPICAL WAVES. THIS WILL FAVOR WET
CONDITIONS THROUGH THE CYCLE FROM THE YUCATAN PENINSULA/NORTHERN
CENTRAL AMERICA...PROGRESSING INTO SOUTHWEST MEXICO BY
THURSDAY/EARLY FRIDAY. A TROPICAL WAVE AND BROAD LOWS IN THE
EASTERN PACIFIC WILL BE THE MAIN MODULATORS OF PRECIPITATIONS. FOR
DETAILS IN ACCUMULATIONS AND TROPICAL WAVE POSITIONS SEE THE
TROPICAL WAVE SECTION.
IN THE CARIBBEAN...A DISORGANIZED UPPER TROUGH PATTERN EXTENDS
NEAR AND TO THE NORTH OF THE GREATER ANTILLES. MODELS ARE
FORECASTING AN ORGANIZATION OF THE UPPER TROUGH ACROSS HISPANIOLA
INTO NORTHERN COLOMBIA BY WEDNESDAY AFTERNOON. THE ELONGATED UPPER
TROUGH IS THEN FORECAST TO MEANDER WESTWARD VERY SLOWLY. THIS WILL
INTERACT WITH A ROBUST TROPICAL WAVE (SEE BELOW)...TO FAVOR THE
DEVELOPMENT OF LOCALLY HEAVY RAINFALL. THE WAVE WILL INITIALLY
ENHANCE CONVECTION IN THE WINDWARD ISLANDS ON TUESDAY...THEN WILL
FOCUS ON PUERTO RICO...VI AND THE LEEWARD ISLANDS ON
WEDNESDAY...AND HISPANIOLA ON THURSDAY. NOTE MODERATE TO LOCALLY
HEAVY ACCUMULATIONS DEVELOPING IN PUERTO RICO/VI/LEEWARD ISLANDS
AND HISPANIOLA ON WEDNESDAY...WHEN EXPECT 15-20MM/DAY AND MAXIMA
OF 30-60MM...BUT ISOLATED HIGHER AMOUNTS CANNOT BE RULED OUT. ON
THURSDAY...EXPECT A PEAK IN ACTIVITY IN HISPANIOLA...WHERE
POSITIVE INTERACTION BETWEEN THE UPPER TROUGH AND THE TROPICAL
WAVE WILL FAVOR 20-40MM/DAY AND MAXIMA OF 50-100MM. IN PUERTO
RICO...TRAILING MOISTURE WILL FAVOR MAXIMA OF 35-70MM MOSTLY IN
SOUTHEASTERN PORTIONS.
IN CENTRAL AMERICA...EXPECT A DECREASING TREND AS A WEAK
TROPOSPHERIC KELVIN MOVES EAST...WHILE A TROPICAL WAVE EXITS THE
REGION. ALTHOUGH THE TROPICAL WAVE IS EXPECTED OVER MEXICO BY
THURSDAY...MOIST ONSHORE FLOW AND FAVORABLE VENTILATION ACROSS
SOUTHERN GUATEMALA AND CHIAPAS WILL FAVOR MAXIMA OF 35-70MM.
IN NORTHERN SOUTH AMERICA...EXPECT MOST ACTIVITY TO ORGANIZE ALONG
THE NET AND A ROBUST TROPICAL WAVE. THE UPPER PATTERN WILL BE
FAVORABLE FOR VENTILATION ON WEDNESDAY ACROSS NORTHERN VENEZUELA
AS THE BASE/SE PORTION OF THE AFOREMENTIONED UPPER TROUGH
INTERACTS POSITIVELY WITH THE TROPICAL WAVE...TO FAVOR SCATTERED
MAXIMA OF 30-60MM. THEN ON THURSDAY...THE DEVELOPMENT OF AN UPPER
RIDGE ACROSS THE WINDWARD ISLANDS WILL SETUP A FAVORABLE REGION OF
UPPER DIVERGENCE ACROSS SURINAME/NORTHERN GUYANA INTO EASTERN
VENEZUELA. THIS WILL FAVOR MAXIMA OF 25-50MM IN WESTERN GUYANA AND
EASTERN VENEZUELA. OTHERWISE...REFER TO THE TROPICAL WAVE SECTION
FOR AMOUNTS.
POSITIONS OF TROPICAL/EASTERLY WAVES INITIALIZED AT 12 UTC
TYPE SOF INIT 28/00 28/12 29/00 29/12 30/00 30/12 01/00 01/12
TW 19N 63W 65W 67W 69W 71W 73W 75W 77W 79W
TW 20N 89W 91W 93W 95W 97W 100W 102W 104W 106W
A TROPICAL WAVE IS INITIALIZED AT 63W AND TO THE SOUTH OF 19N AND
IT IS ACCOMPANIED BY A BROAD CIRCULATION AND HIGH LEVELS OF
PRECIPITABLE WATER...WITH ANALYSES SUGGESTING VALUES REACHING
VALUES CLOSE TO 70MM. ON TUESDAY...IT WILL FAVOR MAXIMA OF 20-35
IN PORTIONS OF ST. VINCENT AND THE GRENADINES...BARBADOS...AND
GRENADA. ELSEWHERE IN THE LESSER ANTILLES AND EAST AND SOUTH
VENEZUELA...THE WAVE WILL FAVOR MAXIMA OF 20-45MM. ON
WEDNESDAY...IT WILL FAVOR MAXIMA OF 30-60MM IN THE LEEWARD
ISLANDS...VI AND PUERTO RICO. SIMILAR AMOUNTS ARE EXPECTED IN
NORTHERN VENEZUELA AND PORTIONS OF THE VENEZUELA ORINOQUIA. ON
THURSDAY...IT WILL FAVOR MAXIMA OF 50-100MM IN HISPANIOLA...WHILE
IN NORTHWEST COLOMBIA IT WILL FAVOR MAXIMA OF 25-50MM.
A TROPICAL WAVE IS INITIALIZED AT 89W AND TO THE SOUTH OF 20N. ON
TUESDAY...THE WAVE WILL FAVOR MAXIMA OF 30-60MM IN WEST EL
SALVADOR/SOUTHERN GUATEMALA AND SOUTH CHIAPAS/SOUTHEAST OAXACA. IT
WILL FAVOR MAXIMA OF 20-45MM FROM SOUTHEAST VERACRUZ TO SOUTHERN
YUCATAN...BELIZE...NORTHERN GUATEMALA...WEST HONDURAS...AND EAST
EL SALVADOR. ON WEDNESDAY...THE WAVE WILL FAVOR MAXIMA OF 30-60MM
IN EAST GUERRERO...PUEBLA...SOUTH VERACRUZ...AND SOUTHWESTERN
CHIAPAS. ON THURSDAY...EXPECT 15-30MM/DAY AND MAXIMA OF 40-80MM
ALONG THE COAST OF OAXACA AND GUERRERO/MICHOACAN. NORTH ACROSS
CENTRAL AND THE REST OF SOUTHWEST MEXICO IT WILL FAVOR MAXIMA OF
20-40MM.
GALVEZ/ACOSTA/ALAMO...WPC (USA)
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