581
FXCA20 KWBC 051954
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
353 PM EDT THU OCT 05 2023
FORECAST BULLETIN 05 OCT 2023 AT 1930 UTC: TROPICAL STORM PHILIPPE
IS CURRENTLY LOCATED 430 MILES OR 695 KM SSW OF BERMUDA. PHILIPPE
IS MOVING NORTH AND IS EXPECTED TO CONTINUE MOVING NORTHWARD OVER
THE NEXT FEW DAYS. PHILIPPE IS CAUSING SOUTHERLY WINDS ACROSS THE
EASTERN CARIBBEAN...WHICH WILL CAUSE ADDITIONAL RAIN ACROSS
PR/USVI AND THE LEEWARD ISLANDS TODAY AND FRIDAY. THAT SAID...A
TROPICAL WAVE IS MOVING THOUGH THE LESSER ANTILLES TODAY AND WOULD
REACH PR/USVI BY FRIDAY...WHICH WOULD HELP IN THE RAINFALL
POTENTIAL. SO MUCH THAT UP TO 50MM IS FORECAST FOR THE WINDWARD
ISLANDS TODAY INTO FRIDAY...THEN UP TO 45MM ACROSS PORTIONS OF
PR/USVI ON FRIDAY INTO SATURDAY. DRIER AIR STARTS MOVING INTO THE
NORTHEAST CARIBBEAN ON SATURDAY...WITH SOME SAHARAN DUST...WHICH
WILL CAUSE A SIGNIFICANT REDUCTION IN RAINFALL ACTIVITY ACROSS THE
LESSER ANTILLES AND PR/USVI.
AT THE SURFACE...THERE IS WEAK HIGH PRESSURE ACROSS THE CENTRAL
ATLANTIC THAT WILL PERSIST OVER THE NEXT SEVERAL DAYS. THERE IS
ALSO A HIGH PRESSURE MOVING INTO THE WESTERN ATLANTIC THAT WILL
WEAKEN AND DISPLACED AS TROPICAL STORM PHILIPPE MOVES NORTH ALONG
THE WESTERN ATLANTIC. THERE IS ALSO A COLD FRONT THAT WILL PUSH
INTO THE GULF OF MEXICO AND INTO THE WESTERN ATLANTIC BY SUNDAY. A
TROPICAL WAVE IS CROSSING THE LESSER ANTILLES TODAY AND WILL
CONTINUE TO MOVE WEST THROUGH THE CARIBBEAN OVER THE WEEKEND. IN
THE MID LEVELS...THERE IS A WEAK BUT BROAD HIGH PRESSURE ACROSS
THE CENTRAL ATLANTIC THAT WILL PERSIST OVER THE NEXT SEVERAL DAYS.
A MID LEVEL LOW PRESSURE AND ASSOCIATED TROUGH WILL MOVE NORTH
ALONG THE WESTERN ATLANTIC AS IT WEAKENS AND GETS ABSORBED BY
SUNDAY BY A MUCH BROADER AND LARGER MID LEVEL LOW MOVING INTO THE
NORTHEAST USA. IN THE UPPER LEVELS THERE IS ALSO A TROUGH
EXTENDING FROM THE WESTERN ATLANTIC INTO THE WESTERN
CARIBBEAN...WHICH WILL ALSO MOVE NORTH ALONG THE WESTERN ATLANTIC
BUT WILL LEAVE VERY STRING WINDS ALOFT ACROSS THE NORTHERN GULF OF
MEXICO AND THE WESTERN ATLANTIC BY SUNDAY. AN UPPER LEVEL HIGH
PRESSURE WILL MOVE INTO THE CARIBBEAN BY SUNDAY AND ANOTHER UPPER
HIGH PRESSURE WILL MOVE INTO CENTRAL MEXICO ON SUNDAY...THOUGH THE
NORTHERN PORTIONS OF MEXICO WILL HAVE VERY STRONG WINDS ALOFT AS
WELL...GENERALLY BETWEEN 70 AND 90 KNOTS EACH DAY. THESE STRONG
WINDS ALOFT MAY PROVIDE VENTILATION FOR THUNDERSTORM
DEVELOPMENT...ESPECIALLY OVER NORTHEASTERN MEXICO AS A COLD FRONT
IS EXPECTED TO PUSH SOUTH AND REACH NORTHEASTERN MEXICO.
SIGNIFICANT RAINFALL IS EXPECTED EACH DAY ACROSS MUCH OF THE
TROPICAL REGION. SOME AREAS WILL OBSERVE OVER 25MM OF RAIN THROUGH
THE WEEKEND...WHILE OTHERS WILL OBSERVE LOWER AMOUNTS OF
RAIN...THOUGH MOST OF THE AREA IS EXPECTED TO RECEIVE AT LEAST
SOME RAIN THOUGH THE WEEKEND.
IN NORTHERN SOUTH AMERICA...COLOMBIA AND VENEZUELA ARE EXPECTED TO
HAVE A FEW SECTORS OBSERVE MAX VALUES OF 25-50 MM OR HIGHER EACH
DAY THROUGH SUNDAY...WHILE THE REST OF NORTHERN SOUTH AMERICA IS
EXPECTED TO OBSERVE MORE ISOLATED TO SCATTERED SHOWER ACTIVITY
WITH ISOLATED WEAK THUNDERSTORMS...AMOUNTING TO MAX VALUES
GENERALLY BETWEEN 15-35MM. THE GUIANAS HOWEVER ARE EXPECTED TO BE
GENERALLY DRY EXCEPT GUYANA WHICH IS EXPECTED TO HAVE OCCASIONAL
THUNDERSTORMS...SOME OF WHICH COULD BE STRONG ENOUGH TO CAUSE OVER
25MM OF RAIN.
THE AREAS OF CENTRAL AMERICA EXPECTING THE MOST SIGNIFICANT
RAINFALL ARE THE PACIFIC SIDE OF EL SALVADOR AND GUATEMALA WITH
MAX VALUES OF UP TO 35MM EACH DAY...WHILE PORTIONS OF WESTERN
PANAMA AND EASTERN COSTA RICA COULD OBSERVE 25-50MM IN
THUNDERSTORMS ON FRIDAY AND SATURDAY. THE ATLANTIC SIDE OF CENTRAL
AMERICA IS EXPECTED TO OBSERVE MUCH LESS RAIN THAN THE REST...WITH
SCATTERED SHOWERS AND MAX VALUES GENERALLY IN THE 10-15MM RANGE.
THINGS GET A LITTLE COMPLICATED IN MEXICO...AS THERE ARE SEVERAL
FACTORS CONTRIBUTING TO AREAS OF SIGNIFICANT RAIN AND
THUNDERSTORMS IN SOME AREAS...WHILE THE CENTRAL PORTION OF MEXICO
COULD OBSERVE MUCH LESS RAINFALL. TROPICAL STORM LIDIA OVER THE
EAST PACIFIC IS MOVING WEST AND AWAY FROM MEXICO...BUT COULD BE
PROMOTING THE ADVECTION OF MOISTURE ACROSS THE WESTERN PART OF
MEXICO. ALTHOUGH THERE IS CONSIDERABLE UNCERTAINTY...THE NATIONAL
HURRICANE CENTER IS FORECASTING LIDIA TO EVENTUALLY TAKE A TURN TO
THE EAST EARLY NEXT WEEK...AND THE LONG RANGE MODELS INDICATE THE
POTENTIAL OF LIDIA REACHING THE WEST COAST OF MEXICO. THAT BEING
SAID...FOR THE PURPOSES OF THIS DISCUSSION...OVER THE NEXT 3
DAYS...THE MOISTURE ADVECTION AND ONSHORE FLOW COULD CAUSE LIFTING
AND THE DEVELOPMENT OF SHOWERS AND THUNDERSTORMS ACROSS THE
COASTAL SECTIONS OF MEXICO. THE STRONG WINDS ALOFT ACROSS NORTHERN
MEXICO ALONG WITH A COLD FRONT THAT IS MOVING SOUTH FROM SOUTHERN
TEXAS INTO NORTHEASTERN MEXICO...COULD CAUSE SIGNIFICANT
THUNDERSTORMS ACROSS PORTIONS OF COAHUILA TO TAMAULIPAS TODAY INTO
FRIDAY..POSSIBLY CAUSING AS MUCH AS 75-125MM ACROSS ISOLATED
AREAS. FROM FRIDAY THROUGH SUNDAY...ADDITIONAL THUNDERSTORMS ARE
POSSIBLE ACROSS PORTIONS OF MEXICO...ESPECIALLY THE NORTH CENTRAL
AS WELL AS PORTIONS OF THE WEST AND EAST COASTS...PRODUCING
ISOLATED TO SCATTERED THUNDERSTORMS WITH MAX VALUES BETWEEN
25-60MM.
POSITIONS OF TROPICAL/EASTERLY WAVES INITIALIZED AT 12 UTC
TYPE SOF INIT 06/00 06/12 07/00 07/12 08/00 08/12 09/00
TW 15N 59W 63W 65W 68W 70W 73W 75W 77W
A TROPICAL WAVE IS INITIALIZED AT 59W AND TO THE SOUTH OF 15N. THE
TROPICAL WAVE IS NOT EXPECTED TO HAVE AN IMPACT IN THE LOCAL
ISLANDS TODAY AND FRIDAY.SIGNIFICANT RAINFALL...OVER 25MM CAN BE
EXPECTED OVER THE WINDWARD ISLANDS TODAY. THE TROPICAL WAVE WILL
CONTINUE MOVING WEST THROUGH THE CARIBBEAN FOR THE NEXT FEW DAYS.
MOST OF THE MOISTURE WILL REMAIN TO THE SOUTH OF THE GREATER
ANTILLES...BUT IT WILL HELP CAUSE SHOWER AND THUNDERSTORM ACTIVITY
ON FRIDAY ACROSS PR/USVI AND THEN ON SATURDAY ACROSS HISPANIOLA.
ALAMO...WPC (USA)
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