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FXCA20 KWBC 181736
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
135 PM EDT TUE JUL 18 2023
FORECAST BULLETIN FROM 18 JUL 2023 AT 1800 UTC: THE SUBTROPICAL
UPPER RIDGE CENTERS IN SOUTHEAST ARIZONA ON TUESDAY....WHERE IT IS
FORECAST TO PERSIST THROUGH THURSDAY. THIS WILL ALLOW FOR EASTERLY
FLOW IN THE MID AND UPPER TROPOSPHERE ACROSS MOST OF MEXICO.
ALTHOUGH THIS GENERALLY IMPLIES WETTER CONDITIONS...THE PRESENCE
OF A DRY AIR MASS OVER THE GULF OF MEXICO WILL FAVOR A DRIER
CONDITIONS THIS TIME. IN ADDITION...A LARGE SCALE UPPER
CONVERGENT/SUBSIDENT PATTERN WILL REINFORCE THE UNSEASONABLY DRY
CONDITIONS YIELDING TO LIMITED COVERAGE OF DIURNAL CONVECTION AND
CONSERVATIVE ACCUMULATIONS. TROPICAL WAVES WILL PLAY A ROLE IN
ENHANCING PRECIPITATION LOCALLY. FROM ALL...THE MOST REMARKABLE IS
THE WAVE FORECAST TO ENTER THE YUCATAN PENINSULA/GUATEMALA ON
THURSDAY. AS THIS WAVE INTERACTS WITH A TUTT LOW RETROGRADING FROM
THE GULF OF HONDURAS...EXPECT ACTIVE CONVECTION FROM
BELIZE/GUATEMALA INTO SOUTHERN VERACRUZ AND THE ENTIRE YUCATAN
PENINSULA ON THURSDAY...WHEN EXPECT 10-15MM/DAY AND MAXIMA OF
20-40MM.
A TUTT LOW CENTERS NEAR THE CAYMAN ISLANDS ON TUESDAY. THE TUTT IS
INTERACTING WITH A TROPICAL WAVE THAT LIES TO THE EAST. POSITIVE
INTERACTION IS TRIGGERING STRONG DEEP CONVECTION IN THE
JAMAICA/EASTERN CUBA REGION ON TUESDAY AFTERNOON. ALTHOUGH
MODERATE ACCUMULATIONS ARE EXPECTED...THERE IS ALSO ENHANCED WIND
SHEAR GIVEN THE CURRENT ACCELERATION OF THE CARIBBEAN TRADES. THE
ATLANTIC TRADES ARE ALSO ACCELERATED AND ASSOCIATE WITH A SAHARAN
AIR LAYER (SAL)...WHICH IS PROPAGATING ACROSS THE NORTHEAST
CARIBBEAN. THE SAL WILL FAVOR VERY LITTLE PRECIPITATION ACROSS THE
LEEWARD ISLANDS AND NORTHEAST CARIBBEAN DURING THE NEXT SEVERAL
DAYS. IN TERMS OF SIGNIFICANT ACCUMULATIONS...ON TUESDAY EXPECT
MAXIMA OF 20-45MM IN MOST OF CENTRAL AND EASTERN CUBA AS THE
TROPICAL WAVE INTERACTS WITH THE TUTT. IN JAMAICA AND THE CAYMAN
ISLANDS EXPECT MAXIMA OF 15-20MM...AS WELL AS IN THE NORTHWEST
BAHAMAS. ON WEDNESDAY...THE HEAVIEST PRECIPITATION WILL CLUSTER IN
WESTERN CUBA WHERE EXPECT MAXIMA OF 20-35MM. A DECREASING TREND
FOLLOWS.
THE ACCELERATION OF THE TRADES IS HIGHLIGHTING THE MID-SUMMER
DROUGHT IN CENTRAL AMERICA...LIMITING ACCUMULATIONS IN THE PACIFIC
BASINS FROM NICARAGUA NORTHWARD. CONSISTENT WITH THIS...THE
LARGEST AMOUNTS ARE FORECAST FOR THE CARIBBEAN
BASIN...PARTICULARLY NICARAGUA/EASTERN HONDURAS WITH A TROPICAL
WAVE ON WEDNESDAY. YET...LIMITED AVAILABLE MOISTURE WILL FAVOR
BELOW-NORMAL AMOUNTS IN OTHER LOCATIONS THROUGH THE CYCLE.
IN NORTHERN SOUTH AMERICA...THE LARGEST AMOUTNS OF PRECIPITABLE
WAVER ARE LOCATED IN GUYANA/VENEZUELA...AND WILL FAVOR MODERATE
PRECIPITATION WITH A TROPICAL WAVE MOVING ACROSS GUYANA ON
TUESDAY. LIMITED AVAILABLE MOISTURE IN AREAS WEST WILL FAVOR A
DECREASE IN THE COVERAGE OF DIURNAL CONVECTION IN
COLOMBIA...FORECAST TO PERSIST INTO THRUSDAY...AIDED AS WELL BY
ACCELERATED MID-LEVEL WINDS. IN TERMS OF RAINFALL AMOUNTS...EXPECT
MAXIMA OF 20-45MM FROM GUYANA THROUGH CENTRAL VENEZUELA ON
TUESDAY. ON WEDNESDAY EXPECT SIMILAR AMOUNTS IN EASTERN AND
CENTRAL VENEZUELA...ALTHOUGH MAXIMA OF 30-60MM IS POSSIBLE IN
PORTIONS OF NORTH-CENTRAL VENEZUELA. ON THURSDAY EXPECT MAXIMA OF
20-35MM ACROSS NORTH-CENTRAL AND NORTHWEST VENEZUELA...INTO
NORTHERN COLOMBIA.
POSITIONS OF TROPICAL/EASTERLY WAVES INITIALIZED AT 12 UTC
TYPE SOF INIT 19/00 19/12 20/00 20/12 21/00 21/12 22/00 22/12
TW 13N 56W 58W 61W 65W 69W 72W 75W 79W 82W
TW 22N 75W 79W 81W 84W 87W 90W 93W 96W 99W
TW 16N 89W 93W 98W 103W 107W 110W 114W EXITS
TW 21N 107W 110W 112W 116W EXITS
A TROPICAL WAVE IS INITIALIZED AT 56W AND SOUTH OF 13N. IT WILL
FAVOR MAXIMA OF 20-35MM IN THE WINDWARD ISLANDS ON TUESDAY...AND
MAXIMA OF 20-45MM IN GUYANA. ON WEDNESDAY IT WILL FAVOR MAXIMA OF
30-60MM IN NORTH-CENTRAL VENEZUELA AND MAXIMA OF 20-45MM ELSEWHERE
IN CENTRAL AND EASTERN VENEZUELA. ON WEDNESDYA IT WILL FAVOR
MAXIMA OF 20-35MM IN NORTHERN COLOMBIA AND WESTERN VENEZUELA.
A TROPICAL WAVE IS INITIALIZED AT 75W AND SOUTH OF 22N. YET
TRAILED BY AN IMPORTANT SAHARAN AIR LAYER AND ASSOCIATED DRY
CONDITIONS...THE WAVE IS INTERACTING WITH A TUTT LOW TO ITS
NORTHWEST. THIS WILL FAVOR MODERATE PRECIPITATION IN
CUBA/JAMAICA/CAYMAN ISLANDS ON TUESDAY...WHEN EXPECT MAXIMA OF
20-45MM IN CUBA AND 15-20MM IN THE CAYMAN ISLANDS/JAMAICA. ON
WEDNESDAY EXPECT MAXIMA OF 20-35MM IN WEST CUBA AND MAXIMA OF
20-40MM IN EASTERN NICARAGUA/EAST HONDURAS. ON THURSDAY EXPECT
MAXIMA OF 20-40MM FROM WESTERN HONDURAS/GUATEMALA/BELIZE INTO
SOUTHERN VERACRUZ AND MOST OF THE YUCATAN PENINSULA.
A TROPICAL WAVE IS INITIALIZED AT 89W AND SOUTH OF 16N. THIS WAVE
IS PROPAGATING VERY RAPIDLY...LIMITING ITS EFFECTS ON CONVECTION.
ON TUESDAY IT WILL MFAVOR MAXIMA OF 15-20MM IN THE YUCATAN
PENINSULA/SOUTHEAST MEXICO AND SOUTHERN GUATEMALA. ON WEDNESDAY IT
WILL FAVOR ISOLATED MAXIMA OF 15-25MM IN SOUTHWEST MEXICO...TO
THEN EXIT THE REGION.
A TROPICAL WAVE IS INITIALIZED AT 107W AND SOUTH OF 21N...AND WILL
HAVE LIMITED EFFECTS ON CONTINENTAL CONVECTION.
GALVEZ/ACOSTA/ALAMO...WPC (USA)
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