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| #1148689 (Received by flhurricane at: 4:56 AM 21.Aug.2023) TCDAT3 Tropical Storm Franklin Discussion Number 3 NWS National Hurricane Center Miami FL AL082023 500 AM AST Mon Aug 21 2023 Franklin`s cloud pattern has not become significantly better organized overnight. The system is producing several clusters of bursting very deep convection, but convective banding features are not well defined at this time. Based on microwave imagery, the cyclone center is apparently located near the western edge of the overall convective mass. The current intensity is held at 45 kt in agreement with a subjective Dvorak satellite classification from TAFB. This value is also supported by objective intensity estimates from UW-CIMSS. The storm continues moving generally westward, with a motion estimate of 270/10 kt. Franklin`s forecast track is somewhat problematic. A weakness in the subtropical ridge is expected to cause the tropical cyclone to turn northward in 24 hours or so. This should result in Franklin crossing Hispaniola in the 48 hour time frame. After moving into the Atlantic, Franklin should turn northeastward while interacting with a mid-level cyclonic circulation. By late in the forecast period, the mid-level cyclone lifts out which could allow Franklin to turn more to the left. However there is more than the usual amount of uncertainty in the 3-5 day track prediction, with lots of spread in the model guidance. The official forecast, like the previous one, is near the middle of the guidance envelope and close to the model consensus. The flow on the south side of a broad upper-level trough to the northwest of Franklin is causing moderate southwesterly vertical wind shear over the storm. Dynamical guidance such as the SHIPS model indicate that Franklin will remain in an environment of moderate shear for the next several days, and the interaction with the mountainous land mass of Hispaniola should temporarily disrupt Franklin`s circulation. The current thinking is that the shear will not be strong enough to prevent the system from eventually becoming a hurricane over the southwest Atlantic. The official intensity forecast follows the model consensus. KEY MESSAGES: 1. Heavy rainfall from Franklin is expected across portions of Puerto Rico and Hispaniola through the middle of the week. The heavy rainfall may produce areas of flash and urban flooding as well as river rises and mudslides. Across Hispaniola, significant and potentially life-threatening flash flooding is possible Tuesday into Wednesday. 2. Franklin is expected to bring tropical storm conditions to portions of the Dominican Republic and Haiti beginning on Tuesday where Tropical Storm Warnings are in effect. FORECAST POSITIONS AND MAX WINDS INIT 21/0900Z 15.0N 69.2W 45 KT 50 MPH 12H 21/1800Z 15.0N 70.4W 50 KT 60 MPH 24H 22/0600Z 15.3N 71.1W 50 KT 60 MPH 36H 22/1800Z 16.7N 71.2W 55 KT 65 MPH 48H 23/0600Z 18.8N 70.9W 45 KT 50 MPH...INLAND 60H 23/1800Z 20.9N 70.2W 45 KT 50 MPH...OVER WATER 72H 24/0600Z 22.5N 69.0W 55 KT 65 MPH 96H 25/0600Z 24.5N 66.0W 60 KT 70 MPH 120H 26/0600Z 26.0N 64.0W 70 KT 80 MPH $$ Forecaster Pasch |
