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Hurricane Larry Forecast Discussion Number 24
2021-09-06 16:56:02| National Hurricane Center (Atlantic)
Issued at 1100 AM AST Mon Sep 06 2021 000 WTNT42 KNHC 061455 TCDAT2 Hurricane Larry Discussion Number 24 NWS National Hurricane Center Miami FL AL122021 1100 AM AST Mon Sep 06 2021 Larry currently has an annular structure, with a 60 n-mi diameter eye and a relatively thick eyewall. High-resolution visible imagery shows several meso-vortices rotating within the eye, which is typically observed in strong hurricanes. The upper-level outflow has become better defined over the western portion of the circulation, indicative of decreased shear in comparison to yesterday. The advisory intensity is kept at 105 kt, in reasonable agreement with the latest Dvorak estimates from TAFB and SAB. Larry has slowed its forward speed a bit, and is now moving northwestward near 9 kt. There are no important changes in the track forecast or reasoning from the previous advisory. During the next few days, the hurricane is expected to move around the western periphery of a subtropical anticyclone over the central Atlantic, turning northward and northeastward. At this time, Larry is forecast to pass east of Bermuda and make its closest approach to the island on Thursday. Given Larry's large size, some impacts could be felt even if the center remains well east of the island as forecast. In 3-5 days, the cyclone should accelerate northeastward ahead of a large mid-tropospheric trough moving through the northeastern United States. The official track forecast follows the latest dynamical model consensus, and remains close to the previous one. Since the model guidance is in good agreement, this continues to be a high-confidence track forecast. Vertical shear is expected to remain low and the system will continue to traverse warm SSTs for the next few days. However, the presence of dry mid-level air and the broad nature of the hurricane's inner core will probably mitigate against significant restrengthening. Some fluctuations in intensity are possible for the next 48 hours or so. In 3-5 days, cooler waters and increasing shear should cause gradual weakening. Around the end of the forecast period, the global models show the system beginning to merge with a frontal zone near Newfoundland. The official forecast is on the high side of the model guidance suite and close to the latest Decay-SHIPS prediction. Key Messages: 1. Large swells generated by Larry are affecting the Lesser Antilles and will spread to portions of the Greater Antilles, the Bahamas, and Bermuda today through Tuesday. Significant swells should reach the east coast of the United States and Atlantic Canada by midweek and continue affecting these shores through the end of the week. These swells will likely cause life-threatening surf and rip current conditions, and beachgoers and other interests along these coasts are urged to follow the guidance of lifeguards and local officials this week. 2. Larry is forecast to approach Bermuda during the next few days as a large and powerful hurricane, bringing a risk of strong winds, heavy rainfall, and coastal flooding to the island by the middle of this week. While it is too soon to determine the magnitude of these hazards and potential impacts on Bermuda, interests there should closely monitor the latest forecast updates during the next several days. FORECAST POSITIONS AND MAX WINDS INIT 06/1500Z 22.1N 52.9W 105 KT 120 MPH 12H 07/0000Z 23.1N 54.0W 110 KT 125 MPH 24H 07/1200Z 24.5N 55.3W 110 KT 125 MPH 36H 08/0000Z 25.9N 56.6W 105 KT 120 MPH 48H 08/1200Z 27.5N 58.0W 100 KT 115 MPH 60H 09/0000Z 29.3N 59.6W 100 KT 115 MPH 72H 09/1200Z 31.6N 61.2W 95 KT 110 MPH 96H 10/1200Z 38.6N 60.0W 85 KT 100 MPH 120H 11/1200Z 49.0N 49.0W 70 KT 80 MPH...POST-TROP/EXTRATROP $$ Forecaster Pasch
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