Prognostic Meteorological Discussion
Issued by NWS
Issued by NWS
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699 FXCA20 KWBC 171932 PMDCA TROPICAL DISCUSSION - INTERNATIONAL DESKS NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 332 PM EDT THU OCT 17 2024 FORECAST BULLETIN 17 OCT 2024 AT 1930 UTC: THE NATIONAL HURRICANE CENTER IS MONITORING TWO AREAS OF POSSIBLE TROPICAL CYCLONE FORMATION IN THE ATLANTIC BASIN. ONE SYSTEM IS KNOWN AS AL94...CURRENTLY NEAR 55W...AND THE OTHER IS AN AREA OF LOW PRESSURE IN THE WESTERN CARIBBEAN. AS OF THIS WRITING...THROUGH 7 DAYS...THE CHANCE OF FORMATION ARE 30 PERCENT FOR AL94...AND ALSO 30 PERCENT FOR THE AREA OF LOW PRESSURE IN THE WESTERN CARIBBEAN. THE LATEST GUIDANCE SUGGESTS THAT THE STRONGEST SHOWERS AND THUNDERSTORMS ASSOCIATED WITH AL94 WILL BE TO THE NORTH OF THE NORTHEAST CARIBBEAN ISLANDS FRIDAY INTO SATURDAY...BUT COULD AFFECT THE TURKS AND CAICOS AS WELL AS THE SOUTHERN BAHAMAS FROM SATURDAY INTO SUNDAY. THE SYSTEM IN THE WESTERN CARIBBEAN COULD PRODUCE SIGNIFICANT RAIN OVER PORTIONS OF NORTHERN CENTRAL AMERICA AND SOUTHERN MEXICO ON FRIDAY THROUGH THE WEEKEND. ACROSS THE ATLANTIC AND EASTERN TROPICAL REGION...OTHER THAN THE TWO SYSTEMS TO MONITOR FOR POSSIBLE TROPICAL CYCLONE FORMATION AND ITS RAINFALL IMPACTS OVER LAND AREAS...THERE IS A BROAD HIGH PRESSURE ACROSS THE EASTERN ATLANTIC...AS WELL AS A LOW PRESSURE IN THE WESTERN ATLANTIC...NEAR 37N/69W. ANOTHER HIGH PRESSURE OVER THE EAST CENTRAL USA THAT IS EXTENDING INTO THE GULF OF MEXICO. THE MONSOON TROUGH IS EXTENDING FROM THE PACIFIC INTO IN THE SOUTHERN CARIBBEAN...WHICH COMBINED WITH THE BROAD LOW PRESSURE IN THE CARIBBEAN...IS CURRENTLY CAUSING SHOWERS AND THUNDERSTORMS ACROSS PORTIONS OF CENTRAL AMERICA AND THE CARIBBEAN SEA. THERE IS ALSO A COLD FRONT THAT IS EXTENDING FROM THE AFOREMENTIONED LOW PRESSURE OVER THE WESTERN ATLANTIC...SOUTHWEST INTO THE BAHAMAS...THEN THE FRONTAL BOUNDARY IS STATIONARY AS IT EXTENDS FROM THE BAHAMAS INTO THE SOUTHERN GULF OF MEXICO. SATELLITE IMAGERY IS CURRENTLY INDICATING CONVECTION OCCURRING ALONG THE FRONTAL BOUNDARY...WHICH IS BEING ENHANCED BY BROAD MID AND UPPER LEVEL LOWS CENTERED OVER THE EASTERN US...BUT THE ASSOCIATED TROUGH AND STRONG MID AND UPPER LEVEL WINDS EXTEND SOUTH INTO THE GULF OF MEXICO AND THE WESTERN TROPICAL ATLANTIC. THIS FRONTAL BOUNDARY IS EXPECTED TO REMAIN STATIONARY FROM THE BAHAMAS TO AROUND THE YUCATAN PENINSULA TODAY AND FRIDAY...WHILE THE COLD FRONT WILL CONTINUE TO THE EAST OF THE BAHAMAS. HOWEVER...BY SATURDAY INTO SUNDAY...A PORTION OF THE FRONTAL BOUNDARY FROM THE BAHAMAS INTO THE EASTERN GULF OF MEXICO WILL TRANSITION TO A COLD FRONT AND WILL START TO DRIFT SOUTH INTO NORTHERN CUBA AND ALONG THE SOUTHERN BAHAMAS...BUT REMAINING STATIONARY OVER THE CENTRAL GULF OF MEXICO. SHOWERS AND THUNDERSTORMS WILL BE EXPECTED ALONG THE FRONTAL BOUNDARY OVER CUBA AND THE BAHAMAS FOR THE REST OF THE WEEK...AS IT INTERACTS WITH THE MID AND UPPER LEVEL TROUGHS...AS WELL AS ALLOWING FOR MOISTURE TO POOL JUST AHEAD OF THE FRONTAL BOUNDARY. IN TERMS OF RAINFALL ACROSS THE REGION...THE MODELS CONTINUE WITH SOME DISAGREEMENTS...BUT COMPARING THE MODEL GUIDANCE AND HOW IT IS INITIALIZING WITH THE CURRENT OBSERVATIONS...THE GFS MODEL SEEMS TO BE CAPTURING THE DEEPER CONVECTION A BIT BETTER...THOUGH THE OVERALL RAINFALL COVERAGE IS BEST BEING CAPTURED BY OTHER MODELS. UNSETTLED AND DISORGANIZED SHOWER AND THUNDERSTORM ACTIVITY IS EXPECTED ACROSS THE TROPICAL REGION OVER THE NEXT FEW DAYS...WITH THE EXCEPTION OF THE THUNDERSTORM ACTIVITY THAT IS EXPECTED TO AFFECT NORTH CENTRAL AMERICA INTO SOUTHERN MEXICO...WHICH IS FORECAST TO BE IN A LARGE CLUSTER OF THUNDERSTORM ACTIVITY MOVING IN...THOUGH THE GFS SHOWS MUCH MORE ORGANIZATION OF THESE THAN THE ECMWF MODEL. THAT BEING SAID...DUE TO THE LOCALIZED CONVECTION EXPECTED ACROSS DIFFERENT SECTIONS OF THE TROPICS...EACH DAY FROM TODAY THROUGH SUNDAY MORNING...DIFFERENT AREAS OF THE TROPICAL REGION WILL HAVE MAX DAILY AMOUNTS REACHING 50MM OR HIGHER. ACCORDING TO THE LATEST GUIDANCE...THE COMBINED 3-DAY RAINFALL FORECAST INDICATES THAT THE AREAS WITH MOST CUMULATIVE RAIN WILL BE SOME SECTORS OF CENTRAL AMERICA FROM BELIZE TO PORTIONS OF SOUTHERN MEXICO. THAT BEING SAID...OUR FORECAST WENT ABOVE THE MODEL RAINFALL SOLUTIONS FOR A FEW SECTORS OF CUBA AND THE BAHAMAS DUE TO THE PROXIMITY TO THE FRONTAL BOUNDARY AND INTERACTING WITH THE MID AND UPPER LEVELS...ESPECIALLY FOR CUBA WHERE IT COULD ALSO INTERACT WITH THE LOCAL TERRAIN EFFECTS. EASTERLY/TROPICAL WAVES INITIALIZED AT 12 UTC TYPE SOF INT 18/00 18/12 19/00 19/12 20/00 20/12 21/00 21/12 TW 21N 55W 58W 62W 66W 68W 71W 73W 75W 76W A TROPICAL WAVE IS INITIALIZED AT 55W AND TO THE SOUTH OF 21N. THIS WAVE IS EXPECTED TO MOVE WEST NORTHWEST. MOST OF ITS CONVECTION AND MOISTURE IS FORECAST TO MOVE NORTH OF THE NORTHEASTERN CARIBBEAN ISLANDS BY THE WEEKEND. HOWEVER...THE WAVE AXIS WILL MOVE THROUGH THE CARIBBEAN OVER THE NEXT FEW DAYS...AND WILL HAVE A BAND OF DEEPER MOISTURE MOVE THROUGH THE LEEWARDS AND INTO THE GREATER ANTILLES THIS WEEKEND. THE NATIONAL HURRICANE CENTER IS MONITORING THIS SYSTEM FOR TROPICAL CYCLONE FORMATION...CURRENTLY WITH A 30 PERCENT CHANCE OF FORMATION THROUGH 7 DAYS. ALAMO...(WPC) $$