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| #1094225 (Received by flhurricane at: 5:06 AM 05.Jun.2022) TCDAT1 Tropical Storm Alex Discussion Number 11 NWS National Hurricane Center Miami FL AL012022 500 AM EDT Sun Jun 05 2022 After the previous advisory, data from the Air Force Reserve Hurricane Hunters and GOES-16 Proxy-Vis satellite imagery indicated that a well-defined center had formed in association with what is now Tropical Storm Alex. With that said, the satellite structure of the storm is hardly classical, with the coldest convective cloud tops all shunted east of the low-level center which is still occasionally reforming northeastward where the strongest convection is located. Earlier, the reconnaissance aircraft found 850-mb flight-level winds up to 72 kt in the southeast quadrant of the circulation. A nearby released dropsonde, however, suggested that these flight-level winds were not mixing down to the surface at the standard reduction factor, and the highest SFMR winds were only between 35-40 kt. Thus, the initial intensity was set to only 45 kt at 0600 UTC and that remains the intensity this advisory. Another reconnaissance aircraft will sample the storm later today. Alex`s general motion continues off to the northeast at 065/19 kt. This motion, with some further acceleration, is expected during the next day or two as the system remains well embedded in the mid-latitude westerly flow off the eastern US coastline. The current track continues to indicate that Alex will make its closest approach to Bermuda Monday afternoon or evening while the cyclone`s track gradually bends eastward. Thereafter, both the GFS and ECMWF suggest Alex`s surface circulation will decouple from the dwindling convection and slow down as it becomes a shallow and stretched-out vortex. The new NHC track maintains the slowdown trend made from the previous advisory after 48 hours following this general shift in the consensus track aids. Some additional short-term strengthening is possible over the next 12 hours as long as Alex remains closely tied to the deep convection. This convection is being aided by strong upper-level difluent flow over the anomalously warm Gulf Stream. However, nearby dry air combined with more than 30 kt of vertical wind shear is forecast to disrupt this convective structure, and the global model guidance suggests the convection could separate from the low-level circulation after 24 hours. Thus, weakening is anticipated to start on Monday. Continuing the trend from the previous forecast cycle, the latest round of guidance suggests that Alex will complete extratropical transition sooner as its circulation loses fidelity in an increasingly baroclinic environment. The latest NHC forecast now indicates the cyclone becoming post-tropical by 48 hours with complete dissipation by 120 hours. However, the latest GFS and ECMWF suggest Alex`s remnant circulation could open up into a trough even sooner than the current forecast. KEY MESSAGES: 1. Alex is forecast to pass near or just north of Bermuda on Monday, and tropical storm conditions are expected on the island on Monday. FORECAST POSITIONS AND MAX WINDS INIT 05/0900Z 29.1N 76.3W 45 KT 50 MPH 12H 05/1800Z 30.5N 74.0W 50 KT 60 MPH 24H 06/0600Z 32.0N 70.0W 50 KT 60 MPH 36H 06/1800Z 33.2N 65.3W 45 KT 50 MPH 48H 07/0600Z 34.0N 60.5W 40 KT 45 MPH...POST-TROP/EXTRATROP 60H 07/1800Z 34.3N 56.4W 35 KT 40 MPH...POST-TROP/EXTRATROP 72H 08/0600Z 34.2N 52.6W 30 KT 35 MPH...POST-TROP/EXTRATROP 96H 09/0600Z 34.7N 49.0W 30 KT 35 MPH...POST-TROP/EXTRATROP 120H 10/0600Z...DISSIPATED $$ Forecaster Papin/Blake |
