|
Show Selection: |
| #1140478 (Received by flhurricane at: 5:06 AM 22.Jun.2023) TCDAT3 Tropical Storm Bret Discussion Number 12 NWS National Hurricane Center Miami FL AL032023 500 AM AST Thu Jun 22 2023 Bret threw some interesting data at us during the couple of hours after the release of the previous advisory. On the last pass of the Air Force Reserve Hurricane Hunter aircraft through Bret`s center, the plane measured SFMR winds as high as 69 kt and a dropsonde surface pressure of 996 mb with 31 kt of wind. Significant mid-level westerly shear is still affecting the system, and a 0539 UTC AMSR2 microwave pass revealed a well-defined mid-level eye feature displaced about a degree to the east of Bret`s low-level center. It appears that the strong SFMR winds were measured beneath the strong convection in the western mid-level eyewall feature, so it`s possible that they were transient and convectively driven. That said, Bret`s initial intensity was raised to 60 kt on the 2 am intermediate advisory out of an abundance of caution, and that remains the current estimate. Another reconnaissance aircraft is scheduled to investigate Bret in a few hours and will hopefully confirm whether or not the storm is still producing winds that strong. Vertical shear is expected to gradually increase over the next couple of days as Bret approaches an upper-level trough located over the eastern Caribbean Sea. The storm could maintain its intensity or fluctuate in intensity through much of today, but it is expected to begin weakening by tonight once it crosses the Lesser Antilles and moves over the eastern Caribbean Sea. Global model fields indicate that Bret should degenerate into a trough over the central Caribbean Sea by day 3, which is shown in the official forecast. There are no changes in the track forecast reasoning. Bret is moving toward the west, or 280/13 kt, steered by a low- to mid-level ridge to its north. An accelerated westward motion is expected during the next few days as Bret weakens, and the NHC track forecast is a little faster than the consensus aids, hedging toward the faster GFS and ECMWF solutions. Users are reminded that NHC`s track forecasts have average errors of about 40 n mi at 24 hours, and there is risk of strong winds and heavy rainfall for several islands within the Lesser Antilles regardless of exactly where the center crosses the island chain. KEY MESSAGES: 1. Bret is forecast to approach the Lesser Antilles today and then move across those islands this evening and tonight as a strong tropical storm. 2. A Hurricane Watch and a Tropical Storm Warning are in effect for St. Lucia, and a Tropical Storm Warning is in effect for Martinique and Dominica. There is a risk of flooding from heavy rainfall, strong winds, and dangerous waves along the coast within the warning area. A Tropical Storm Watch remains in effect for Barbados and St. Vincent and the Grenadines. Additional watches or warnings are possible for some islands in the Lesser Antilles later today. FORECAST POSITIONS AND MAX WINDS INIT 22/0900Z 13.7N 56.6W 60 KT 70 MPH 12H 22/1800Z 13.9N 58.8W 60 KT 70 MPH 24H 23/0600Z 14.1N 61.8W 55 KT 65 MPH 36H 23/1800Z 14.3N 65.2W 50 KT 60 MPH 48H 24/0600Z 14.4N 68.7W 45 KT 50 MPH 60H 24/1800Z 14.6N 72.2W 40 KT 45 MPH 72H 25/0600Z...DISSIPATED $$ Forecaster Berg |
