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| #1105535 (Received by flhurricane at: 5:00 AM 03.Sep.2022) TCDAT5 Tropical Storm Danielle Discussion Number 9 NWS National Hurricane Center Miami FL AL052022 900 AM GMT Sat Sep 03 2022 Convection associated with Danielle has continued to decrease this morning, with a corresponding decrease in satellite intensity estimates. Based on this decrease, it is estimated that Danielle has weakened to a tropical storm with an initial intensity of 60 kt. While it is not known why the storm has weakened, one possibility is that the slow motion has allowed the cyclone to upwell cold water underneath it. Danielle is essentially stationary with a 12-h motion of 270/1 kt. The cyclone is still caught south of a blocking high over the North Atlantic. This pattern is expected to hold firm for a couple of days, with the system forecast to drift westward and then drift northward. After 48-60 h, the block will weaken and allow the southern edge of the mid-latitude westerlies to steer Danielle generally northeastward at a faster forward speed. There are no significant changes to the forecast track for the first 48-60 h. After that, the forecast has been nudged eastward due to a shift in the guidance envelope. The intensity guidance is still calling for Danielle to strengthen for 72 h or so. Given the possibility of upwelling and the forecast continued slow motion, the guidance might be a bit optimistic on that. The new intensity forecast calls for little change in strength for 12 h or so, followed by slow strengthening on the premise that the storm will move over somewhat warmer water. After 72 h, the storm is likely to interact with an upper-level trough, which could help maintain the intensity even as Danielle moves toward much colder water in the North Atlantic. This trough will also start extratropical transition, although this will likely not be complete by 120 h. FORECAST POSITIONS AND MAX WINDS INIT 03/0900Z 38.0N 43.8W 60 KT 70 MPH 12H 03/1800Z 38.0N 44.1W 60 KT 70 MPH 24H 04/0600Z 38.1N 44.7W 65 KT 75 MPH 36H 04/1800Z 38.5N 44.7W 70 KT 80 MPH 48H 05/0600Z 39.1N 44.3W 75 KT 85 MPH 60H 05/1800Z 39.9N 43.6W 75 KT 85 MPH 72H 06/0600Z 40.7N 42.6W 75 KT 85 MPH 96H 07/0600Z 43.0N 39.5W 70 KT 80 MPH 120H 08/0600Z 46.5N 35.5W 65 KT 75 MPH $$ Forecaster Beven |
