THE WEATHER PREDICTION CENTER

COLLEGE PARK, MD


CARIBBEAN FORECAST DISCUSSION




TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
311 PM EDT THU AUG 13 2020

TROPICAL DISCUSSION FROM AUGUST 13/16UTC: NORTHWEST IN THE
DOMAIN...A TUTT LOW CENTERS OVER THE GULF OF MEXICO AND IS
EXTENDING AN AXIS TO THE WEST INTO CENTRAL MEXICO. THE TUTT WILL
MOVE LITTLE THROUGH THE FORECAST CYCLE...TO SLOWLY MEANDER
WESTWARD. BY FRIDAY IT WILL CENTER OFF THE COAST OF NORTHERN
VERACRUZ AND EXTEND AN AXIS INTO NORTHERN JALISCO/NAYARIT. THIS
WILL VENTILATE CONVECTION IN AREAS TO THE SOUTH OF THE TUTT
AXIS...WHILE AREAS RO THE NORTH WILL BE UNDER THE INFLUENCE OF A
DRIER AIR MASS FROM THE SOUTHERN PLAINS OF THE UNITED STATES.
THUS...STRONGEST CONEVCTION IN MEXICO WILL EXTEND FROM THE YUCATAN
PENINSULA INTO JALISCO/NAYARIT AND SOUTHERN SINALOA THROUGH THE
FORECAST CYCLE. AT LOW-LEVELS...A TROPICAL WAVE IS ENHANCING
CONVECTION WHILE TRANSVERSING CENTRAL MEXICO ON WEDNESDAY. THIS
WILL FAVOR 10-15MM/DAY AND MAXIMA OF 20-40MM FROM WESTERN
OAXACA/GUERRERO INTO SOUTHERN SINALOA ON WEDNESDAY. ON
THURSDAY...EXPECTING SIMILAR ACCUMULATIONS CLUSTERING FROM
COLIMA/JALISCO INTO NORTHERN SINALOA. BY FRIDAY...EXPECTING A
DECREASE IN ACCUMULATIONS TO 05-10MM/DAY AND MAXIMA OF 15-25MM IN
AREAS TO THE SOUTH OF SOUTHERN SINALOA. ANOTHER SYSTEM TO ENHANCE
CONVECTION IS A TUTT-INDUCED PERTURBATION. THIS WILL SUSTAIN A
PEAK IN ACTIVITY IN THE YUCATAN PENINSULA ON THURSDAY TO FAVOR
10-15MM/DAY AND MAXIMA OF 20-35MM. ON FRIDAY...SIMILAR AMOUNTS ARE
FORECAST TO CLUSTER IN TABASCO/NORTHERN CHIAPAS. ON SATURDAY...

TO THE EAST...A TUTT LOW CENTERS OVER THE CENTRAL BAHAMAS AND
EXTENDS INTO THE CAYMAN ISLANDS ON THURSDAY. THE TUTT IS FORECAST
TO MOVE LITTLE THROUGH THE CYCLE...TO MEANDER INTO THE NORTHWEST
BAHAMAS ON FRIDAY AND SATURDAY...AND THEN RETURN TO ITS ORIGINAL
POSITION. THIS WILL INTERACT WITH MOIST PLUMES IN THE TRADES AND
WAVES TO SUSTAIN PRECIPITATION IN THE REGION. HOWEVER...GIVEN
LIMITED AMOUNTS OF AVAILABLE MOISTURE...EXTREME RAINFALL IS NOT
EXPECTED. ON THURSDAY...THIS WILL SUSTAIN 05-10MM/DAY AND MAXIMA
OF 15MM IN WESTERN CUBA AND IN SOUTHEAST CUBA...CAYMAN ISLANDS AND
WESTERN HAITI...IN INTERACTION WITH A TROPICAL WAVE. ON
FRIDAY...LARGEST AMOUNTS ARE EXPECTED IN ISOLATED STRONG
CONVECTION IN WESTERN CUBA AND THE WESTERN BAHAMAS...WHERE
EXPECTING 05-10MM/DAY AND MAXIMA OF 15-20MM. IN THE CAYMANS AND
JAMAICA EXPECTING MAXIMA OF 15MM. ON SATURDAY...EXPECTING ISOLATED
CONVECTION IN THE NORTHWEST BAHAMAS TO SUSTAIN 05-10MM/DAY AND
MAXIMA OF 15-20MM.

IN THE REST OF THE CARIBBEAN...MID-LEVEL RIDGE PATTERN WILL BE THE
DOMINANT FEATURE ON THURSDAY TO SUSTAIN FAIR WEATHER CONDITIONS
AND ISOLATED MAXIMA UNDER 10MM/DAY IN THE LESSER ANTILLES...PUERTO
RICO AND HISPANIOLA. VERY ISOLATED AFTERNOON CONVECTION IN EXTREME
WESTERN PUERTO RICO WILL SUSTAIN MAXIMA OF 15-25MM. ON FRIDAY...A
MOIST PLUME ACROSS THE LEEWARD ISLANDS AND PUERTO RICO WILL
ENHANCE CONVECTION AIDED BY A WEAKENING OF THE TRADE WIND CAP.
THIS WILL FAVOR 05-10MM/DAY AND MAXIMA OF 15MM. ISOLATED MAXIMA OF
15-25MM IS LIKELY IN SOUTHWEST PUERTO RICO. ON SATURDAY...MORE
SIGNIFICANT CONVECTION IS EXPECTED IN ASSOCIATION WITH INDIRECT
EFFECTS OF TROPICAL STORM JOSEPHINE...FORECAST TO PASS NORTH OF
THE ISLANDS. THIS WILL FAVOR 10-15MM/DAY AND MAXIMA OF 20-40MM IN
THE NORTHERN LEEWARD ISLANDS...NORTHERN VIRGIN ISLANDS AND
NORTHERN PUERTO RICO. IN THE LESSER ANTILLES...MOIST PLUME AND
TROUGH ASSOCIATED WITH JOSEPHINE WILL FAVOR 05-10MM/DAY AND MAXIMA
OF 15-25MM.

WET PATTERN IS UNRAVELING IN SOUTHERN CENTRAL AMERICA...AS A
TROPICAL WAVE INTERACTS WITH AN ACTIVE ITCZ...ENHANCED BY THE
CURRENT LARGE SCALE UPPER DIVERGENT PATTERN ASSOCIATED WITH THE
MADDEN-JULIAN OSCILLATION. ON THURSDAY...EXPECTING 15-20MM/DAY AND
MAXIMA OF 30-60MM IN WESTERN PANAMA AND MOST OF COSTA RICA...WHILE
MCS DEVELOPMENT IS LIKELY IN THE GULF OF PANAMA INTO EARLY HOURS
OF FRIDAY...TO FAVOR 25-50MM/DAY AND MAXIMA OF 75-125MM. ON
FRIDAY...HEAVY RAINFALL IS LIKELY IN WESTERN PANAMA...MOST OF
COSTA RICA AND SOUTHERN NICARAGUA...WHERE EXPECTING 25-50MM/DAY
AND MAXIMA OF 75-125MM. ON FRIDAY...EXPECTING STILL HEAVY RAINFALL
AND THE CHANCE OF MCS FORMATION IN COSTA RICA AND SOUTHERN
NICARAGUA...WHERE ACCUMULATIONS ARE LIKELY TO REACH 25-50MM/DAY
AND MAXIMA OF 75-150MM. IN WESTERN PANAMA EXPECTING MAXIMA OF
20-40MM.

IN NORTHERN SOUTH AMERICA...ACTIVE CONVECTION IS EXPECTED IN
COLOMBIA ESPECIALLY EARLY IN THE CYCLE IN ASSOCIATION WITH THE
TROPICAL WAVE AND ENHANCED UPPER DIVERGENT PATTERN. THIS WILL
FAVOR 15-20MM/DAY AND MAXIMA OF 30-60MM IN CENTRAL AND NORTHERN
COLOMBIA ON THURSDAY...WHILE IN NORTHWEST COLOMBIA EXPECTING
MAXIMA OF 75-125MM. SIMILAR AMOUNTS ARE EXPECTED ON FRIDAY...WHILE
A DECREASE IS EXPECTED ON SATURDAY...WHEN FORECAST AMOUNTS IN
COLOMBIA WILL RANGE 10-15MM/DAY AND MAXIMA OF 20-40MM. TO THE
EAST...SEASONAL CONVECTION WILL OCCUR IN A DAILY BASIS ALONG THE
NET IN NORTHERN VENEZUELA...AND IN EASTERN COLOMBIA/CENTRAL
VENEZUELA AND NORTHERN GUYANA TO SUSTAIN 05-10MM/DAY AND MAXIMA OF
15-25MM ON A DAILY BASIS. VERY ISOLATED LARGER AMOUNTS ARE
POSSIBLE IN THE STRONGEST THUNDERSTORMS. ONSHORE FLOW IN THE
GUIANAS ON SATURDAY WILL SUSTAIN AN INCREASE IN COASTAL CONVECTION
TO FAVOR 10-15MM/DAY AND ISOLATED MAXIMA OF 20-35MM.

TROPICAL WAVES/TUTT INDUCED PERTURBATIONS/TRADE WIND SURGES
TYPE  13/12  14/00  14/12  15/00  15/12  16/00  16/12  17/00 SOF
TI      58W    62W    66W    68W    70W    73W    76W    78W 29N
TW      74W    79W    78W    82W    85W    88W    90W    93W 24N
TI      88W    90W    92W    94W    96W    98W   100W   102W 26N
TW     105W   108W   110W   112W   114W   116W   118W   120W 25N

A TUTT-INDUCED PERTURBATION IS INITIALIZED AT 58W AND TO THE SOUTH
OF 29N...AND NORTH OF 18N. THIS WAVE WILL APPROACH THE LEEWARD
ISLANDS ON THURSDAY TO SUSTAIN ONLY A MARGINAL ENHANCEMENT OF
CONVECTION GIVEN THAT ENHANCEMENT WILL CLUSTER GENERALLY NORTH OF
THE CARIBBEAN ISLAND CHAIN.

A TROPICAL WAVE IS INITIALIZED AT 74W AND TO THE SOUTH OF 24N. THE
WAVE IS PROPAFATING RAPIDLY. ON THURSDAY...THE WAVE WILL INTERACT
WITH THE PANAMANIAN LOW TO TRIGGER STRONG CONVECTION AND A RISK
FOR MCS FORMATION IN THE GULF OF PANAMA. EXPECTING 25-50MM/DAY AND
MAXIMA OF 75-125MM IN NORTHWEST COLOMBIA AND EXTREME SOUTHERN
PORTIONS OF THE AZUERO PENINSULA/EASTERN PANAMA. IN THE REST OF
PANAMA...MOST OF COSTA RICA AND CENTRAL/NORTHERN COLOMBIA
EXPECTING 15-20MM/DAY AND MAXIMA OF 30-60MM. ON FRIDAY...THE WAVE
WILL ENHANCE CONVECTION IN WESTERN PANAMA...COSTA RICA AND
SOUTHERN NICARAGUA IN ASSOCIATION WITH AN ENHANCED PANAMABIAN LOW
CIRCULATION. THIS WILL FAVOR 25-50MM/DAY AND MAXIMA OF 75-150MM
WITH THE RISK FOR MCS FORMATION. IN NORTHERN NICARAGUA AND EASTERN
HONDURAS IT WILL FAVOR 10-15MM/DAY AND MAXIMA OF 20-45MM...WHILE
IN WESTERN HONDURAS AND EL SALVADOR IT FACORS 05-10MM/DAY AND
MAXIMA OF 15-25MM. IN SOUTHERN BELIZE AND CENTRAL GUATEMALA...THE
WAVE WILL COMBINE WITH EHNANCED TRADE WIND CONVERGENCE TO FAVOR
15-20MM/DAY AND MAXIMA OF 25-50MM. ON SATURDAY...THE WAVE WILL
FAVOR MAXIMA OF 20-35MM FROM SOUTHERN BELIZE/CENTRAL GUATEMALA
INTO VERACRUZ/TABASCO IN MEXICO...WHILE IN EL SALVADOR...HONDURAS
AND SOUTHERN GUATEMALA EXPECTING 05-10MM/DAY AND MAXIMA OF
15-25MM.

A TUTT INDUCED PERTURBATION IS INITIALIZED AT 88W...AND IS
FORECAST TO PROPAGATE FROM THE YUCATAN PENINSULA ON THURSDAY TO
THE WESTERN GULF OF MEXICO/VERACRUZ BY SATURDAY. THIS WILL SUSTAIN
A PEAK IN CONVECTION IN THE YUCATAN PENINSULA ON THURSDAY WHEN
EXPECTING 10-15MM/DAY AND MAXIMA OF 20-35MM. ON FRIDAY...EXPECTING
SIMILAR AMOUNTS IN TABASCO AND SOUTHERN VERACRUZ. ON
SATURDAY...THIS WILL FAVOR 10-15MM/DAY AND MAXIMA OF 20-35MM IN
VERACRUZ/HIDALGO AND NORTHERN PUEBLA.

ANOTHER TROPICAL WAVE IS INITIALIZED AT 105W AND TO THE SOUTH OF
25N. ON THURSDAY...THE WAVE WILL ENHANCE CONVECTION FROM
JALISCO/COLIMA NORTH INTO NORTHERN SINALOA TO PRODUCE SIMILAR
AMOUNTS. BY FRIDAY...THE EFFECTS OF THE WAVE WILL BE MOSTLY
LIMITED TO THE OPEN WATERS OF THE EASTERN PACIFIC.

GALVEZ/DAVISON...WPC (USA)




Last Updated: 311 PM EDT THU AUG 13 2020