Issued at 1000 AM EST Fri Nov 17 2023
763 WTNT42 KNHC 171434 TCDAT2 Potential Tropical Cyclone Twenty-Two Discussion Number 4 NWS National Hurricane Center Miami FL AL222023 1000 AM EST Fri Nov 17 2023 First-light visible satellite images indicate that the disturbance is still a surface trough of low pressure with nearly all of the deep convection to the east of the trough axis streaming northward across Jamaica, Haiti, and eastern Cuba. Surface pressures remain low--about 1004 mb--but the center of circulation is ill defined. Maximum winds are still estimated to be 30 kt, primarily within the deep convection. The system appears to be accelerating northeastward with an initial motion of 045/12 kt. A continued northeastward acceleration is anticipated during the next day or two as the disturbance moves ahead of a mid-level trough moving across Florida and the far northwestern Caribbean Sea. With the circulation being so broad, however, global model wind fields suggest the system may jump discontinuously rather than move seamlessly across the Greater Antilles during the next 24 hours. The NHC track forecast favors the faster model solutions and is generally a blend of the previous forecast with the latest GFS solution. The prospects for the disturbance to become a tropical cyclone appear to be decreasing. The system is already battling strong southwesterly shear and mid-level dry air, and none of the global models any longer depicts the development of a well-defined circulation. The new NHC forecast therefore keeps the system as a disturbance through tonight, with some possibility (albeit decreasing) of the system becoming a tropical depression or tropical storm after it passes the mountainous terrain of Jamaica and southeastern Cuba. In whatever form the system emerges over the western Atlantic over the weekend, it is likely to become extratropical or merge with a front over the weekend. Despite the decreasing chance of tropical cyclone formation, there is high confidence that heavy rainfall and flooding will remain a distinct and serious threat across Jamaica, southeastern Cuba, and Hispaniola. Additional rainfall amounts of 4 to 8 inches, with isolated areas as high as 16 inches, are forecast in these areas and are likely to produce life-threatening flash flooding and mudslides. KEY MESSAGES: 1. Potential Tropical Cyclone Twenty-Two could produce tropical storm conditions, especially in areas of heavy rainfall, across Jamaica, southeastern Cuba, Haiti, the southeastern Bahamas, and the Turks and Caicos Islands through Saturday, and tropical storm watches are in effect for these areas. 2. Heavy rains will impact portions of Jamaica, southeastern Cuba, and southern Hispaniola through Sunday. This rainfall is likely to produce flash flooding, along with mudslides in areas of higher terrain. Lighter amounts across the southeastern Bahamas as well as the Turks and Caicos Islands may lead to flash flooding in urban areas. FORECAST POSITIONS AND MAX WINDS INIT 17/1500Z 17.5N 79.1W 30 KT 35 MPH...POTENTIAL TROP CYCLONE 12H 18/0000Z 19.3N 76.8W 30 KT 35 MPH...POTENTIAL TROP CYCLONE 24H 18/1200Z 21.9N 73.3W 35 KT 40 MPH...TROPICAL STORM 36H 19/0000Z 25.2N 68.9W 35 KT 40 MPH 48H 19/1200Z 28.3N 64.8W 40 KT 45 MPH...POST-TROP/EXTRATROP 60H 20/0000Z 31.8N 61.0W 40 KT 45 MPH...POST-TROP/EXTRATROP 72H 20/1200Z...ABSORBED BY A FRONT $$ Forecaster Berg
