445  
FXCA20 KWBC 291811  
PMDCA  
 
TROPICAL DISCUSSION - INTERNATIONAL DESKS  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
211 PM EDT FRI SEP 29 2023  
 
FORECAST BULLETIN 29 SEP 2023 AT 1800 UTC: THE NATIONAL HURRICANE  
CENTER IS MONITORING TWO TROPICAL STORMS IN THE ATLANTIC BASIN.  
TROPICAL STORM PHILIPPE...WHICH CONTINUES TO HAVE A HIGHER THAN  
NORMAL UNCERTAINTY...AND TROPICAL STORM RINA. BOTH TROPICAL STORMS  
ARE FORECAST BY THE NATIONAL HURRICANE CENTER TO REMAIN AWAY FROM  
LAND AREAS IN THE CARIBBEAN. HOWEVERâ€TROPICAL STORM PHILIPPE IS  
MOVING VERY SLOWLY AND...COULD CAUSE AN INCREASE IN MOISTURE  
ACROSS THE NORTHEAST CARIBBEAN AND THEN CAUSE LOCALLY SCATTERED TO  
NUMEROUS SHOWERS ACROSS THE LEEWARD ISLANDS INTO PR/USVI THIS  
WEEKEND.  
 
A SFC HIGH PRESSURE EXITING THE EAST COAST OF CANADA WILL MOVE  
INTO THE NW ATLANTIC. A SFC LOW PRESSURE WILL DEVELOP JUST EAST OF  
THE MID ATLANTIC COAST OF THE US AND MOVE SLOWLY TO THE EAST. A  
TROUGH ACROSS THE SOUTHWESTERN GULF OF MEXICO...INTO THE YUCATAN  
PENINSULA WILL PREVAIL OVER THE AREA FOR THE NEXT FEW DAYS. THERE  
IS ALSO A TROPICAL WAVE ALONG 95W BRINGING MOISTURE AND SHOWER  
ACTIVITY TO PORTIONS OF CENTRAL AMERICA AND SOUTHERN MEXICO. IN  
THE MID LEVELS...A BROAD HIGH PRESSURE IS LOCATED IN THE  
ATLANTIC...WITH ITS CENTER TO THE NORTH OF THE GREATER ANTILLES  
UNTIL SATURDAY. FROM SUNDAY INTO MONDAYâ€A TILTED MID-LEVEL  
TROUGH FROM THE WESTERN ATLANTIC INTO THE GULF OF MEXICO WILL BE  
ASSOCIATED WITH A MID-LEVEL LOW ACROSS THE WESTERN ATLANTIC. THERE  
IS AN UPPER LEVEL LOW ACROSS THE SOUTHERN CARIBBEAN INTO THE NORTH  
PORTION OF SOUTH AMERICA...MOVING WEST INTO CENTRAL AMERICA  
THROUGH THIS WEEKEND...WHICH WILL HELP IN THE DEVELOPMENT OF  
SHOWERS AND THUNDERSTORMS ACROSS CENTRAL AMERICA THIS WEEKEND.  
 
IN MEXICO...THE YUCATAN PENINSULA AND SOUTHERN MEXICO ARE STILL  
EXPECTED TO OBSERVE RAINFALL EACH DAY OVER THE 3-DAY FORECAST  
PERIOD...DUE TO THE SURFACE TROUGH. SATURDAY INTO SUNDAY IS STILL  
FORECAST TO BE THE WETTEST PERIOD ACROSS THE AREA...AS IT HAS  
SUPPORT FROM AN UPPER TROUGH. RAINFALL TOTALS ON SATURDAY INTO  
SUNDAY WILL HAVE MAX VALUES OF 25-50MM. LESSER AMOUNTS OF RAIN ARE  
EXPECTED TODAY INTO SATURDAY...WITH MAX VALUES BETWEEN 20-35MM AND  
15-25MM ON SUNDAY INTO MONDAY. THE WEST COAST OF OF MEXICO IS  
EXPECTED TO OBSERVE SHOWERS AND THUNDERSTORMS EACH DAY FOR THE  
NEXT 3 DAYS...THOUGH GENERALLY IN THE ORDER OF 05-10MM/DAY WITH  
MAX UP TO 25MM. HOWEVERâ€ISOLATED SECTIONS OVER FROM JALISCO TO  
OAXACA ARE FORECAST TO OBSERVE 20-35MM. EAST CENTRAL TO NORTHEAST  
FROM VERACRUZ TO TAMAULIPAS IS FORECAST TO OBSERVE RAIN TODAY INTO  
SATURDAY MORNING...WITH MAX TOTALS UP TO 10MMâ€BUT MINIMAL RAIN  
FOR THE REST OF THE WEEKEND INTO MONDAY.  
 
IN THE CARIBBEAN...MOST OF THE RAINFALL ACROSS THE LESSER ANTILLES  
IS EXPECTED TO BE DUE TO BRIEF SHOWERS UNDER A NORTHEASTERLY WIND  
FLOW. LOCALLY INDUCED SHOWERS AND THUNDERSTORMS COULD AFFECT  
ISOLATED AREAS OF SOUTHWESTERN PR AND PORTIONS OF HISPANIOLA IN  
THE AFTERNOON HOURS EACH DAY...WHICH COULD AMOUNT TO OVER 25-35MM.  
OTHERWISE...BRIEF SHOWERS WOULD AFFECT THE WINDWARD SIDE OF THE  
GREATER ANTILLES. THE ADVECTED SHOWERS EXPECTED MAY CAUSE RAINFALL  
TOTALS OF UP TO 10MM ACROSS HISPANIOLA...PUERTO RICO AND USVI EACH  
DAY...WITH THE EXCEPTION OF THE VERY ISOLATED AREAS THAT WERE  
MENTIONED. 10-15MM IS POSSIBLE ACROSS THE LESSER ANTILLES EACH DAY  
THROUGH THE WEEKEND.  
 
IN CENTRAL AMERICA...THE MOISTURE THAT IS AVAILABLE WILL HELP IN  
THE DEVELOPMENT OF SHOWERS AND THUNDERSTORMS THROUGH THE WEEKEND.  
MOST AREAS OF CENTRAL AMERICA ARE FORECAST TO HAVE SOME  
RAIN...WITH THE MAX TOTALS RANGING BETWEEN 15 AND 35MM. THAT  
SAID...PORTIONS OF GUATEMALA AND WESTERN EL SALVADOR COULD HAVE AS  
MUCH AS 30-60MM TODAY INTO SATURDAY WITH THE TRAILING MOISTURE  
FROM THE TROPICAL WAVE OVER THE AREA. THEN MAX TOTALS OF 20-45MM  
ARE FORECAST FROM SATURDAY INTO SUNDAYâ€THEN LESSER RAINFALL  
AMOUNTS ARE FORECAST ON SUNDAY INTO MONDAY.  
 
IN NORTHERN SOUTH AMERICA...SOUTHWESTERN COLOMBIA INTO ECUADOR ARE  
THE AREAS WITH THE MOST SIGNIFICANT RAINFALL TODAY INTO FRIDAY  
WITH TOTALS UP TO AROUND 60MM AS WELL AS SUNDAY INTO MONDAY.  
NORTHEASTERN COLOMBIA AND MOST OF VENEZUELA ARE EXPECTED TO  
OBSERVE UP TO 25MM TODAY. SATURDAY INTO SUNDAY COULD HAVE MORE  
THUNDERSTORM ACTIVITY OVER CENTRAL TO EASTERN COLOMBIA...WITH  
RAINFALL UP TO 45MM. NORTHEASTERN PERU IS FORECAST TO OBSERVE  
GENERALLY 05-10MM AND UP TO 25MM TODAY AND THROUGH THE WEEKEND.  
THE GUIANAS ARE STILL FORECAST TO OBSERVE MINIMAL RAINFALL EACH  
DAY...IF ANY.  
 
POSITIONS OF TROPICAL/EASTERLY WAVES INITIALIZED AT 12 UTC  
TYPE SOF INIT 30/00 30/12 01/00 01/12 02/00 02/12 03/00  
03/12  
TW 19N 95W 97W 100W 102W 104W 106W 108W 110W  
112W  
 
A TROPICAL WAVE IS INITIALIZED AT 95W AND TO THE SOUTH OF 19N. IT  
HAS ABUNDANT MOISTURE ASSOCIATED WITH IT AND IT IS OVER SOUTHERN  
MEXICO. THE TROPICAL WAVE IS FORECAST TO CONTINUE MOVING WEST OVER  
THE NEXT FEW DAYS. THIS TROPICALâ€WITH ITS TRAILING MOISTURE WAVE  
COULD BRING SIGNIFICANT RAIN TO GUATEMALA AND SOUTHERN MEXICO  
TODAY INTO EARLY SATURDAY.  
 
ALAMO...WPC (USA)  
 

 
 
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