180
FXCA20 KWBC 031908
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
308 PM EDT TUE OCT 03 2023
FORECAST BULLETIN 03 OCT 2023 AT 1830 UTC: THE NATIONAL HURRICANE
CENTER CONTINUES TO ISSUE ADVISORIES ON TROPICAL STORM
PHILIPPE...WHICH IS CURRENTLY ABOUT 55 MILES NORTHEAST OF ST
THOMAS USVI. TROPICAL STORM PHILIPPE IS MOVING TO THE
NORTHWEST...AND IS EXPECTED TO GRADUALLY TRACK NORTHWARD ON
WEDNESDAY INTO THURSDAY. PHILIPPE IS EXPECTED TO CAUSE HEAVY RAIN
ACROSS THE LEEWARD ISLANDS...USVI AND PUERTO RICO. THE FORECAST
FOR THE 3-DAY ACCUMULATED RAIN FOR THOSE AREAS IS AS HIGH AS
200-300MM TOTAL FOR PORTIONS OF THE LEEWARD ISLANDS...WHILE
PR/USVI COULD OBSERVE AS MUCH AS 50-100MM. MOST OF THE RAINFALL IS
EXPECTED TO BE TODAY INTO WEDNESDAY...THOUGH SOUTHERLY WINDS
BRINGING MOISTURE WOULD CONTINUE TO CAUSE SHOWERS ACROSS THE
LESSER ANTILLES AND NORTHEAST CARIBBEAN INTO FRIDAY. THERE IS ALSO
A TROPICAL WAVE THAT IS EXPECTED TO CROSS THE LESSER ANTILLES LATE
THURSDAY INTO FRIDAY...WHICH WILL CAUSE ADDITIONAL RAINFALL FOR
THE WINDWARD ISLANDS. ACROSS THE EASTERN PACIFIC...TROPICAL STORM
LIDIA IS MOVING TO THE NORTHWEST AND IS EXPECTED TO REMAIN OVER
THE WATERS.
ACROSS THE REST OF THE TROPICAL REGION...THERE ARE SEVERAL
FEATURES THAT ARE CAUSING SIGNIFICANT RAINFALL IN SOME
AREAS...WHILE OTHERS WILL RECEIVE MORE MODEST AMOUNTS EVERY DAY.
THE MODEL GUIDANCE UNFORTUNATELY WAS NOT IN MUCH AGREEMENT ACROSS
MANY SECTORS OF THE TROPICS...IN PARTICULAR ACROSS NORTHERN SOUTH
AMERICA AND PORTIONS OF MEXICO AND CENTRAL AMERICA.
HOWEVER...THERE WERE SOME GENERAL AGREEMENTS IN SOME SECTIONS. IN
AREAS WHERE THE MODELS DIFFERED GREATLY FROM EACH OTHER...WE SPLIT
THE DIFFERENCE AND NUDGED THE FORECAST ONE WAY OR ANOTHER
DEPENDING ON THE SYNOPTIC FEATURES.
AT THE SURFACE...THERE IS A HIGH PRESSURE DEVELOPING ACROSS THE
CENTRAL ATLANTIC. THERE IS ALSO A HIGH PRESSURE MOVING INTO THE
WESTERN ATLANTIC AS IT MOVES OFFSHORE FROM THE NORTHEAST US...AND
A STATIONARY FRONT FROM THE CENTRAL ATLANTIC INTO THE NORTHERN
BAHAMAS. IN THE MID LEVELS...THERE IS A BROAD HIGH PRESSURE ACROSS
THE CENTRAL ATLANTIC...A TROUGH ACROSS THE WESTERN ATLANTIC THAT
WILL DIG DOWN INTO THE WESTERN CARIBBEAN AS A MID LEVEL LOW
DEVELOPS ON THURSDAY ACROSS THE NORTHERN BAHAMAS. THEN IN THE
UPPER LEVELS THERE IS ALSO A TROUGH EXTENDING FROM THE WESTERN
ATLANTIC INTO THE WESTERN CARIBBEAN...WHICH WILL AMPLIFY INTO
THURSDAY...AND AFFECT THE NORTHWESTERN SECTIONS OF SOUTH AMERICA
AND PORTIONS OF CENTRAL AMERICA...PROVIDING VENTILATION AND
INCREASING INSTABILITY...INCREASING THE POTENTIAL FOR SIGNIFICANT
RAINFALL WITH THUNDERSTORMS.
MOST OF THE TROPICAL REGION HAS ABOVE NORMAL MOISTURE...AND NEAR
TO ABOVE THAN NORMAL MOISTURE THROUGH THURSDAY IS EXPECTED.
THEREFORE MOST AREAS IN THE TROPICS ARE FORECAST AT LEAST SOME
RAINFALL. HOWEVER...IN ADDITION TO THE LEEWARDS...PUERTO RICO AND
THE USVI WITH PHILIPPE...PORTIONS OF NORTHWESTERN SOUTH AMERICA
AND SOME AREAS IN CENTRAL AMERICA ARE EXPECTED TO OBSERVE VERY
SIGNIFICANT RAINFALL TODAY AND TOMORROW. THIS IS DUE TO THE
AVAILABLE MOISTURE COMBINING WITH THE MID AND UPPER LEVEL TROUGHS
THAT ARE EXPECTED TO AFFECT THE AREA. RAINFALL TOTALS WITH MAX
VALUES OF 40-80MM ARE FORECAST FOR TODAY ACROSS NORTHWESTERN
COLOMBIA AND NORTHWESTERN VENEZUELA...BUT WEST CENTRAL TO
SOUTHWESTERN COLOMBIA COULD OBSERVE NEAR 75-100MM ACROSS ISOLATED
AREAS. A FEW SECTORS OF PANAMA AND COSTA RICA COULD ALSO OBSERVE
BETWEEN 25 AND 60MM TODAY. AS WE MOVE NORTH IN CENTRAL
AMERICA...THE PACIFIC SECTORS OF NICARAGUA AS WELL AS EL SALVADOR
ARE FORECAST UP TO 45MM TODAY...WHILE NORTHEASTERN
NICARAGUA...HONDURAS...GUATEMALA AND SOUTHERN MEXICO IS FORECAST
TO OBSERVE UP TO 15-25MM. THE WESTERN COAST OF MEXICO IS FORECAST
UP TO 20-45MM HOWEVER. IN THE CARIBBEAN THE GREATER
ANTILLES...FROM HISPANIOLA TO CUBA ARE FORECAST GENERALLY 05-10MM
WITH MAX VALUES UP TO 15-35MM.
WEDNESDAY INTO THURSDAY WILL HAVE SIGNIFICANT SHOWERS AND
THUNDERSTORMS AS WELL...BUT NOT AS MUCH AS TODAY. NORTHWESTERN
SOUTH AMERICA INTO CENTRAL AMERICA IS FORECAST TO OBSERVE
THUNDERSTORMS...WHICH COULD PRODUCE AS MUCH AS 40-80MM ACROSS
ISOLATED AREAS. MUCH LOWER AMOUNTS OF RAIN ARE FORECAST ELSEWHERE
IN SOUTH AMERICA...UP TO 25MM OR SO...WHILE THE PACIFIC SIDE OF
CENTRAL AMERICA IS FORECAST AS MUCH AS 45MM FROM NICARAGUA TO
SOUTHWESTERN MEXICO...AND THE NORTHERN HALF OF NICARAGUA TO
SOUTHERN MEXICO IS FORECAST MAX VALUES BETWEEN 10-15MM. THE
WESTERN COAST OF MEXICO INTO NORTH CENTRAL...THE RAINFALL COULD
HAVE MAX VALUES OF 15-35MM. THE CARIBBEAN AND THE BAHAMAS WILL
HAVE VARYING AMOUNTS OF RAIN...THOUGH MOST OF THE RAIN WILL BE
BETWEEN 05-15MM WITH MAX VALUES BETWEEN 20-45MM...BUT THE HIGH
RAINFALL AMOUNTS WILL BE VERY LOCALIZED AND DEPENDENT ON THE
INDIVIDUAL LOCAL EFFECTS...AS PHILIPPE TRACKS NORTH AND AWAY FROM
THE LEEWARD ISLANDS. A VERY SIMILAR SITUATION IS FORECAST FOR THE
CARIBBEAN AND THE BAHAMAS ON THURSDAY INTO FRIDAY. THAT
SAID...ELSEWHERE ON THURSDAY INTO FRIDAY APPEARS TO BE THE PERIOD
WITH THE FEWEST NUMBER SIGNIFICANT THUNDERSTORMS AND VERY HIGH
RAINFALL AMOUNTS. WITH THE EXCEPTION OF A SMALL AREA OF
SOUTHEASTERN VENEZUELA...WHICH COULD OBSERVE 40-80MM...THE REST OF
NORTHERN SOUTH AMERICA IS FORECAST MAX VALUES BETWEEN
15-40MM...WITH THE NORTHWESTERN SECTIONS ON THE HIGHER END OF THE
RANGE. ONCE AGAIN FOR CENTRAL AMERICA INTO SOUTHERN MEXICO...MOST
AREAS WILL OBSERVE MAX RAINFALL VALUES BETWEEN 15-35MM ON THURSDAY
INTO FRIDAY. WESTERN TO NORTH CENTRAL MEXICO IS ALSO FORECAST TO
HAVE MAX VALUES BETWEEN 15-35MM.
POSITIONS OF TROPICAL/EASTERLY WAVES INITIALIZED AT 12 UTC
TYPE SOF INIT 04/00 04/12 05/00 05/12 06/00 06/12 07/00
TW 17N 49W 52W 54W 56W 59W 62W 65W 68W
A TROPICAL WAVE IS INITIALIZED AT 49W AND TO THE SOUTH OF 17N. THE
TROPICAL WAVE IS NOT EXPECTED TO HAVE AN IMPACT IN THE LOCAL
ISLANDS UNTIL THURSDAY INTO FRIDAY...WHEN IT IS EXPECTED TO REACH
THE WINDWARD ISLANDS...CAUSING SOME RAINFALL ACROSS THE AREA. THE
TROPICAL WAVE SEEMS TO WEAKEN AND LOSE DEFINITION THEREAFTER AS
PHILIPPE COULD BE DISRUPTING THE TROPICAL WAVE AS IT MOVES THROUGH
THE CARIBBEAN. BECAUSE THERE IS SOME UNCERTAINTY ON THAT WE TRACK
THE WAVE TO THE LOCATION THAT IT WOULD BE EXPECTED TO BE ON FRIDAY
NIGHT.
ALAMO...WPC (USA)
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