654
FXCA20 KWBC 071722
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
121 PM EDT FRI JUL 07 2023
FORECAST BULLETIN FROM 07 JUL 2023 AT 1730 UTC: A BROAD KELVIN
WAVE IS CROSSING THE CARIBBEAN AND CENTRAL AMERICA. THIS IS
ENHANCING THE COVERAGE OF PRECIPITATING CONVECTION AS WELL AS
RAINFALL AMOUNTS. THIS IS ALSO HIGHLIGHTING CONVECTION ALONG THE
PACIFIC ITCZ/MONSOON TROUGH AND STIMULATING A BROAD CIRCULATION
LOCATED WELL TO THE SOUTHWEST OF MEXICO...WHICH IS BEING MONITORED
BY THE NHC. AS THE KELVIN WAVE EXITS THE REGION THROUGH THE
WEEKEND...EXPECT THE ESTABLISHMENT OF AN UPPER CONVERGENT AND
GENERALLY DRIER PATTERN. THIS COINCIDES WITH THE BEGINNING OF THE
MID-SUMMER DROUGHT/CANICULA...AND WILL RESULT IN A NOTICEABLE
ACCELERATION OF THE EASTERLY TRADES ACROSS THE ENTIRE TROPICAL
ATLANTIC AND CARIBBEAN. UNDER THIS PATTERN...EXPECT A GENERAL
TRANSITION TOWARDS DRIER AND WINDIER CONDITIONS ACROSS THE
CARIBBEAN DURING THE WEEKEND...INCLUDING THE ARRIVAL OF A SAHARAN
AIR LAYER.
WEST IN THE DOMAIN...THE SUBTROPICAL UPPER RIDGE IS MEANDERING IN
FAR NORTHWEST MEXICO...MOVING FROM CENTRAL BAJA CALIFORNIA ON
FRIDAY TO SOUTHERN ARIZONA BY MONDAY. THIS IS VENTILATING DEEP
CONVECTION ALONG ITS SOUTHEASTERN PERIPHERY. IN THE LOW AND MID
TROPOSPHERE...TWO TROPICAL WAVES WILL PLAY A ROLE IN ENHANCING
DIURNAL CONVECTION AS THEY MOVE ACROSS MEXICO. MOREOVER...INDIRECT
INFLUENCE OF BROAD CYCLONIC CIRCULATIONS IN THE PACIFIC WILL
POTENTIALLY ENHANCE RAINFALL AMOUNTS IN PORTIONS OF THE COAST OF
SOUTHERN AND SOUTHWEST MEXICO. ON FRIDAY EXPECT MAXIMA OF 35-70MM
IN PORTIONS OF WESTERNM EXICO AND MAXIMA OF 20-35MM IN CENTRAL
MEXICO. ON SATURDAY...EXPECT MAXIMA OF 25-50MM IN NAYARIT/SINALOA
AND IN OAXACA/CHIAPAS...AND MAXIMA OF 20-35MM IN MOST OF CENTRAL
MEXICO AND IN JALISCO. ON SUNDAY...EXPECT MAXIMA OF 40-80MM IN
OAXACA/GUERRERO AND MAXIMA OF 20-40MM IN PORTIONS OF CENTRAL
MEXICO AND THE CENTRAL SIERRA MADRE OCCIDENTAL.
GENERALLY FAIR WEATHER CONDITIONS ARE EXPECTED IN THE CARIBBEAN
THROUGH THE CYCLE WITH THE EXCEPTION OF A FAST MOVING TROPICAL
WAVE (SEE BELOW)...FORECAST TO PRODUCE SHORT-LIVED ENHANCEMENT OF
CONVECTION IN THE LESSER ANTILLES ON FRIDAY...PUERTO
RICO/HISPANIOLA ON SATURDAY...TO THEN LIMITS ITS EFEFCTS ON
RAINFALL AS A SAHARAN AIR LAYER TAKES OVER. OTHERWISE...ISOLATED
DEEP CONVECTION IS EXPECTED IN THE BAHAMAS ON FRIDAY...TO PRODUCE
MAXIMA OF 15-25MM...DECREASING GRADUALLY THEREAFTER.
SEASONABLY WET CONDITIONS ARE EXPECTED TO CONTINUE IN CENTRAL
AMERICA THROUGH THE WEEKEND. YET...A SIGNIFICANT ACCELERATION OF
THE TRADES WILL LIKELY START DEVELOPING DRIER CONDITIONS ON
SUNDAY/MONDAY AND INTO NEXT WEEK. YET...ENHANCED TRADE WIND
CONVERGENCE SOUTH OF THE LOW-LEVEL JETS WILL CONTINUE TO FAVOR
NUMEROUS ROUNDS OF MODERATE-TO-LOCALLY HEAVY RAINFALL IN SOUTHEAST
NICARAGUA/NORTHEAST COSTA RICA AND ADJACENT CARIBBEAN ISLANDS INTO
EARLY NEXT WEEK. FOR AMOUNTS REFER TO THE TROPICAL WAVE SECTION
AND FORECAST CHARTS.
IN SOUTH AMERICA...A DRYING TREND IS ALSO UNDERWAY AS THE
TROPOSPHERIC KELVIN EXITS AND THE EASTERLY TRADES ACCELERATE
BRINGING IN A DRIER AIR MASS FROM THE TROPICAL ATLANTIC.
STILL...ACTIVE CONVECTION IS EXPECTED IN PORTIONS OF COLOMBIA AND
WESTERN/SOUTHERN VENEZUELA ON FRIDAY AND SATURDAY MOSTLY IN
ASSOCIATION WITH A TROPICAL WAVE.
POSITIONS OF TROPICAL/EASTERLY WAVES INITIALIZED AT 12 UTC
TYPE SOF INIT 08/00 08/12 09/00 09/12 10/00 10/12 11/00 11/12
TW 12N 59W 62W 66W 70W 74W 79W 82W 85W 89W
TW 21N 89W 91W 94W 97W 99W 101W 104W 107W 110W
TW 26N 103W 105W 108W DISS
A TROPICAL WAVE IS INITIALIZED AT 59W AND SOUTH OF 12N. THIS WAVE
IS FORECAST TO PROPAGATE VERY RAPIDLY ACROSS THE CARIBBEAN IN
ASSOCIATION WITH THE CURRENT ACCELERATED TRADES. NOTE THAT THIS
WAVE IS TRAILED BY A SAHARAN AIR LAYER...WHICH IS EXPECTED TO HAVE
ITS STRONGEST IMPACTS IN THE GREATER ANTILLES/NORTHERN CARIBBEAN.
IN TERMS OF PRECIPITATION...EXPECT MAXIMA OF 20-35MM IN THE
LEEWARD ISLANDS AND CENTRAL LESSER ANTILLES ON FRIDAY...WHILE IN
NORTHEAST VENEZUELA/TRINIDAD EXPECT MAXIMA OF 15-25MM. ON
SATURDAY...EXPECT SCATTERED MAXIMA OF 25-50MM IN WESTERN VENEZUELA
AND EASTERN COLOMBIA...WHILE IN HISPANIOLA AND NORTHWEST VENEZUELA
EXPECT MAXIMA OF 15-25MM. TRAILING MOISTURE WILL FAVOR MAXIMA OF
20-35MM IN EASTERN PUERTO RICO AS WELL AS IN THE LEEWARD ISLANDS.
ON SUNDAY...EXPECT MAXIMA OF 15-30MM IN NORTHWEST COLOMBIA..PANAMA
AND SOUTHERN COSTA RICA. IN EASTERN NICARAGUA/EASTERN COSTA RICA
AND SAN ANDRES EXPECT MAXIMA OF 20-40MM.
A TROPICAL WAVE IS INITIALIZED AT 89W AND SOUTH OF 21N. IT WILL
FAVOR MAXIMA OF 40-80MM IN SOUTHERN GUATEMALA/SOUTHERN CHIAPAS ON
FRIDAY...WHILE IN EL SALVADOR/SOUTHWEST HONDURAS EXPECT MAXIMA OF
25-50MM. IN NORTHERN HONDURAS/BELIZE/NORTHERN GUATEMALA INTO
SOUTHEAST MEXICO EXPECT MAXIMA OF 20-35MM. ON SATURDAY...IT WILL
FAVOR MAXIMA OF 25-50MM FROM SOUTHERN CHIAPAS INTO OAXACA...WHILE
IN CENTRAL AND EASTERN MEXICO IT FACORS MAXIMA OF 20-35MM. ON
SUNDAY...IT WILL FAVOR MAXIMA OF 40-80MM IN WESTERN
OAXACA/GUERRERO...WHILE IN THE EJE VOLCANICO EXPECT MAXIMA OF
20-40MM.
A TROPICAL WAVE IS INITIALIZED AT 103W AND SOUTH OF 26N. IT WILL
FAVOR MAXIMA OF 35-70MM IN WEST MEXICO ON FRIDAY. ON SATURDAY IT
WILL LOSE DEFINITION AS A BROAD CYCLONIC CIRCULATION WELL TO THE
SOUTHWEST OF CONTINENTAL MEXICO BECOMES THE DOMINANT FEATURE.
STILL...REMANING MOISTURE WILL FAVOR MAXIMA OF 25-50MM IN
SINALOA/NAYARIT.
GALVEZ/ACOSTA/ALAMO...WPC (USA)
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