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| #1061064 (Received by flhurricane at: 4:59 PM 10.Sep.2021) TCDAT2 Hurricane Larry Discussion Number 41 NWS National Hurricane Center Miami FL AL122021 500 PM AST Fri Sep 10 2021 Even though Larry is crossing the north wall of the Gulf Stream Current, the hurricane remains well organized and has changed little during the past several hours. Satellite images and radar data indicate that Larry still has an inner core, though the southern side has eroded some. Large curved bands surround the inner core region, with dry slots noted between the core and bands. The initial intensity is held at 70 kt based mostly on the ASCAT data from earlier today, which showed peak winds of around 65 kt to the east of the center. It should be noted that this intensity value is above the Dvorak estimates, which are often not as reliable for high latitude storms like Larry. The earlier ASCAT data confirmed that Larry is a large cyclone with hurricane-force and tropical-storm-force winds extending outward up to 90 n mi and 220 n mi from the center, respectively. Larry is rapidly approaching southeastern Newfoundland, and weather conditions are expected to begin to deteriorate there in a few hours. The hurricane continues to accelerate to the north-northeast, and the latest initial motion estimate is 020/30 kt. An even faster north-northeast to northeast motion is expected during the next day or so as the hurricane moves in the fast flow between a mid- to upper-level trough over the northeastern U.S./eastern Canada and a mid-level ridge over the central Atlantic. This motion should take Larry across southeastern Newfoundland tonight. Larry is then expected to merge with a large extratropical low over the Labrador Sea on Sunday. The NHC track forecast is largely an update of the previous one and near the middle of the tightly clustered models. Larry is expected to maintain its intensity through landfall in Newfoundland tonight. However, a combination of land interaction, much cooler SSTs, and an increase in shear are expected to promote weakening shortly after landfall. Larry should be fully extratropical early Saturday morning when it is forecast to be exiting Newfoundland and moving over the cold waters of the Labrador Sea. The NHC intensity forecast remains close to the GFS model, which often performs well for hurricanes that transition to extratropical cyclones. Key Messages: 1. Larry is forecast to move over portions of southeastern Newfoundland tonight as it undergoes transition to a hurricane-force post-tropical cyclone. Hurricane conditions, a dangerous storm surge, and heavy rainfall are expected in portions of southeastern Newfoundland where a Hurricane Warning in effect. 2. Large swells generated by Larry will continue to affect the Bahamas, Bermuda, and the east coast of the United States and Atlantic Canada through Saturday night. These swells will 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. FORECAST POSITIONS AND MAX WINDS INIT 10/2100Z 43.5N 58.2W 70 KT 80 MPH 12H 11/0600Z 48.6N 53.3W 65 KT 75 MPH...POST-TROP/EXTRATROP 24H 11/1800Z 54.9N 46.9W 60 KT 70 MPH...POST-TROP/EXTRATROP 36H 12/0600Z 58.6N 42.4W 60 KT 70 MPH...POST-TROP/EXTRATROP 48H 12/1800Z...DISSIPATED $$ Forecaster Cangialosi |