730
FXCA20 KWBC 211636
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1236 PM EDT FRI JUL 21 2023
FORECAST BULLETIN FROM 21 JUL 2023 AT 1630 UTC: PRECIPITABLE WATER
HAS INCREASED ACROSS THE WESTERN GULF OF HONDURAS/YUCATAN
PENINSULA IN RESPOND TO SEVERAL DAYS OF ENHANCED MOISTURE
CONVERGENCE DUE TO THE ACCELERATED CARIBBEAN TRADE WINDS. THIS
WILL FAVOR AN INCREASE IN PRECIPITATION IN PORTIONS OF SOUTHERN
AND CENTRAL MEXICO AND NORTHERN CENTRAL AMERICA...AS THE MOISTER
AIR MASS PROPAGATES WESTWARD. NOTE THAT AN EXTENSIVE SAHARAN AIR
LAYER AND ASSOCIATED DRY AIR TRAIL BEHIND THIS REGION...WHICH WILL
FAVOR A DRYING TREND ACROSS BELIZE...THE YUCATAN PENINSULA AND
PORTIONS OF CENTRAL MEXICO EARLY NEXT WEEK. A TROPICAL WAVE
PROPAGATING ACROSS OAXACA/VERACRUZ ON FRIDAY WILL ALSO PLAY A ROLE
IN ENHANCING CONVECTION LOCALLY. ON FRIDAY...THE MOST REMARKABLE
AMOUNTS IN MEXICO ARE FORECAST TO CLUSTER FROM CENTRAL OAXACA WEST
INTO GUERRERO...WHERE EXPECT 15-20MM/DAY AND MAXIMA OF 25-50MM. IN
THE YUCATAN PENINSULA...NORTHERN GUATEMALA/BELIZE AND OTHER
PORTIONS OF SOUTHEAST MEXICO EXPECT MAXIMA OF 20-35MM...AS WELL AS
IN SOUTHWEST MEXICO. ON SATURDAY...EXPECT MAXIMA OF 20-45MM FROM
GUATEMALA/SOUTHERN BELIZE INTO THE WESTERN YUCATAN PENINSULA AND
VERACRUZ/CHIAPAS. WEST INTO NAYARIT EXPECT MAXIMA OF 20-35MM. ON
SUNDAY...EXPECT A NOTICEABLE DECREASE IN BELIZE/NORTHERN GUATEMALA
AND AREAS NORTH IN ASSOCIATION WITH THE SAL. ACROSS SOUTHWEST AND
CENTRAL MEXICO EXPECT MAXIMA OF 20-35MM.
A PROMINENT SAHARAN AIR LAYER IS EXTENDS FROM THE TROPICAL
ATLANTIC ACROSS THE LESSER ANTILLES INTO THE JAMAICA...CUBA AND
THE BAHAMAS ON FRIDAY. THIS IS LIMITING PRECIPITATION IN THE
REGION AND IS FORECAST TO PERSIST INTO MONDAY...AS THE SAL
CONTINUES PROPAGATING WEST. A TROPICAL WAVE IS APPROACHING THE
GUIANAS ON MONDAY. AN INCREASE IN AVAILABLE MOISTURE WITH AND
AHEAD OF THIS SYSTEM WILL FAVOR AN INCREASE IN TRARE WIND SHOWERS
ACROSS THE CENTRAL MESSER ANTILLES ON SUNDAY...WHEN EXPECT MAXIMA
OF 15MM.
AN INCREASING TREND IN PRECIPITATION IS EXPECTED FOR CENTRAL
AMERICA...AS THE CURRENT ACCELERATED TRADE WIND REGIME WEAKENS
SOME...AND A TROPOSPHERIC KELVIN WAVE APPROACHES THE BASIN. A
TROPICAL WAVE IS MOVING ACROSS PANAMA ON FRIDAY AS WELL...YET THE
SIGNATURE OF CONVECTION WITH THIS WAVE IS ILL-DEFINED DUE TO THE
INFLUENCE OF ENHANCED WIND SHEAR AND LIMITED AVAILABLE MOISTURE.
YET...THE WAVE WILL ENHANCE AFTERNOON AND EVENING CONVECTION
ACROSS WESTERN PANAMA AND COSTA RICA ON FRIDAY...WHERE EXPECT
10-15MM/DAY AND MAXIMA OF 20-45MM...WHILE THE CARIBBEAN BASINS OF
NICARAGUA...HONDURAS AND GUATEMALA SHOULD EXPECT MAXIMA OF
20-35MM. ON SATURDAY...EXPECT MAXIMA OF 20-45MM IN EASTERN
HONDURAS AND NORTHEAST NICARAGUA...WHILE EXPECT MAXIMA OF 20-35MM
IN PANAMA AND SOUTHERN COSTA RICA. ENHANCED VENTILATION BETWEEN A
TUTT LOW IN THE PACIFIC AND AN UPPER RIDGE IN THE GULF OF HONDURAS
WILL FAVOR MAXIMA OF 20-45MM IN WESTERN EL SALVADOR AND GUATEMALA
ON SATURDAY. ON SUNDAY...EXPECT MAXIMA OF 25-50MM IN EL SALVADOR
AND SOUTHERN AND CENTRAL GUATEMALA...WHILE TRADE WIND CONVERGENCE
FAVORS SIMILAR AMOUNTS ALONG EASTERN NICARAGUA. IN COSTA RICA AND
PANAMA EXPECT MAXIMA OF 15-25MM.
IN NORTHERN SOUTH AMERICA...MID-TROPOSPHERIC SOUTHEASTERLY WINDS
REMAIN ACCELERATED ACROSS COLOMBIA...WHICH IS ENHANCING ADIABATIC
COMPRESSION IN AREAS NORTHWEST OF THE ANDES...LIMITING CONVECTIVE
DEVELOPMENT. THIS WILL HOLD ON FRIDAY...ALTHOUGH THERE IS AN
INCREASING TREND UNDERWAY UNDER THE INFLUENCE OF A WEAKENING OF
THE WINDS AND AN APPROACHING KELVIN WAVE. FURTHERMORE...A BROAD
TUTT EXTENDS OVER THE SOUTHERN CARIBBEAN CENTERING NORTH OF THE
GUAJIRA PENINSULA ON FRIDAY. THE TUTT IS FORECAST TO RETROGRADE TO
CENTER SOUTH OF JAMAICA ON SUNDAY...WHILE EXTENDING INTO HONDURAS
AND PANAMA. THIS WILL FAVOR ENHANCEMENT OF CONVECTION IN NORTHERN
COLOMBIA AND NORTHERN VENEZUELA ON FRIDAY. EXPECT MAXIMA OF
30-60MM IN NORTHERN VENEZUELA AND MAXIMA OF 20-45MM IN NORTHERN
AND NORTHWEST COLOMBIA. ON SATURDAY...EXPECT MAXIMA OF 20-40MM IN
MOST OF VENEZUELA AND MAXIMA OF 20-34MM IN NORTHWEST COLOMBIA. ON
SUNDAY...EXPECT MAXIMA OF 20-35MM IN NORTHWEST COLOMBIA...AND
MAXIMA OF 15-25MM ELSEWHERE IN COLOMBIA INTO WESTERN VENEZUELA. IN
SOUTHERN VENEZUELA/RORAIMA EXPECT MAXIMA OF 20-35MM.
POSITIONS OF TROPICAL/EASTERLY WAVES INITIALIZED AT 12 UTC
TYPE SOF INIT 22/00 22/12 23/00 23/12 24/00 24/12 25/00 25/12
TW 15N 38W 40W 41W 42W 43W 45W 48W 52W 56W
TW 13N 77W 80W 82W 84W 86W 89W 92W 95W 99W
TW 25N 95W 97W 99W 101W 103W 105W 107W 109W 111W
TW 23N 112W 116W EXITS
A TROPICAL WAVE IS INITIALIZED AT 38W AND IS FORECAST TO ARRIVE
INTO THE GUIANAS LATE ON MONDAY.
A TROPICAL WAVE IS INITAILIZED AT 77W AND SOUTH OF 13N. THIS WAVE
IS INTERACTING WITH A DRY AIR MASS IN THE CARIBBEAN...WHICH IS
LIMITING ITS EFFECTS ON PRECIPITATION. STILL...IT WILL FAVOR
MAXIMA OF 20-45MM IN SOUTHERN COSTA RICA AND WEST PANAMA ON
FRIDAY. ON SATURDAY EXPECT MAXIMA OF 20-45MM IN EASTERN HONDURAS
AND NORTHEAST NICARAGUA. ON SUNDAY EXPECT MAXIMA OF 25-50MM IN
GUATEMALA AND EL SALVADOR.
A TROPICAL WAVE IS INITIALIZED AT 95W AND SOUTH OF 25N. IT WILL
FAVOR MAXIMA OF 25-50MM IN GUERRERO/WESTERN OAXACA. ON SATURDAY IT
WILL FAVOR MAXIMA OF 20-35MM IN MICHOACAN/GUANAJUATO. ON SUNDAY IT
WILL FAVOR MAXIMA OF 20-35MM IN SOUTHWEST MEXICO.
A TROPICAL WAVE INITIALIZED AT 112W AND 23N IS EXITING THE REGION.
GALVEZ/ACOSTA...WPC (USA)
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