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| #1149141 (Received by flhurricane at: 5:06 PM 23.Aug.2023) TCDAT3 Tropical Storm Franklin Discussion Number 13 NWS National Hurricane Center Miami FL AL082023 500 PM EDT Wed Aug 23 2023 Franklin is in the process of emerging off the northern coast of the Dominican Republic, where surface observations recently showed a subtle wind shift in the past couple of hours. Earlier, a NOAA reconnaissance mission flew a counterclockwise route around the eastern portion of Hispaniola, finding a peak 700-mb wind of 51 kt at about the time of the prior advisory. An ASCAT-B pass at around the same time also showed a decent swath of tropical-storm-force winds along the southern coast of the Dominican Republic. While Franklin has been inland for some time now, given the lack of much other data, its winds will remain 35 kt for this advisory. An Air Force Reserve Reconnaissance mission is soon set to take off and should provide more data this evening. Franklin`s motion is now estimated to be north-northeastward at 015/11 kt. A large weakness in the flow north of Franklin should allow the storm to be steered by mid-level ridging nosing back into the eastern Caribbean in the short-term, leading to a rather unusual east-northeastward motion over the next 24-48 hours. Then, after the remnants of Emily move out of the way, additional ridging should build back east of Franklin, blocking it from an immediate track out to sea. The track guidance all show the cyclone bending back northward for the remainder of the forecast period. While the track guidance generally agree on this evolution, the details on when and how sharply this turn is remain to be ironed out. Ultimately, the consensus aids have changed little this afternoon, even if the spread in the ensemble guidance is larger than normal, and the NHC track is very similar to the prior one throughout the forecast period. The biggest hindrance limiting Franklin`s initial prospects for reintensification is continued moderate westerly vertical wind shear between 15-25 kt for the next 24-48 hours. However, sea-surface temperatures will be very warm along the forecast track, so this shear should not be enough to preclude slow intensification during that time span. Afterwards, an upper-level trough is expected to cutoff to the southwest of Franklin as the cyclone begins to pivot northward, and the storm should find itself in a more favorable upper-level environment. Thus, a faster intensification rate is anticipated between 72-96 h and Franklin is still expected to become a significant hurricane by the end of the forecast period. The intensity forecast is in good agreement with the consensus aids, but remains lower than some of the more aggressive hurricane-regional models (HWRF, HAFS-A/B). KEY MESSAGES: 1. Heavy rainfall from Franklin is expected across much of Hispaniola into Thursday, which is expected to produce significant and potentially life-threatening flash and urban flooding as well as mudslides, particularly over the central Dominican Republic. 2. Franklin is bringing tropical storm conditions to portions of the Dominican Republic, where Tropical Storm Warnings remain in effect, and tropical storm conditions are expected to begin within the Turks and Caicos Islands tonight. FORECAST POSITIONS AND MAX WINDS INIT 23/2100Z 19.8N 70.6W 35 KT 40 MPH...ON THE COAST 12H 24/0600Z 21.4N 70.1W 40 KT 45 MPH 24H 24/1800Z 22.5N 68.8W 45 KT 50 MPH 36H 25/0600Z 23.0N 67.5W 50 KT 60 MPH 48H 25/1800Z 23.3N 66.3W 55 KT 65 MPH 60H 26/0600Z 23.8N 65.6W 60 KT 70 MPH 72H 26/1800Z 24.6N 65.5W 65 KT 75 MPH 96H 27/1800Z 28.0N 67.0W 85 KT 100 MPH 120H 28/1800Z 31.6N 67.4W 90 KT 105 MPH $$ Forecaster Papin |
