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#1152857 (Received by flhurricane at: 5:03 PM 14.Sep.2023) TCDAT3 Hurricane Lee Discussion Number 38 NWS National Hurricane Center Miami FL AL132023 500 PM AST Thu Sep 14 2023 There has been little overall change to the satellite presentation of Lee since the previous advisory. Deep convection continues to develop near the center, but it is primarily confined to the northern portion of the circulation. Southwesterly shear and dry air entrainment is disrupting the convective banding over the southern portion of the storm. The initial intensity was lowered to 75 kt on the 1800 UTC intermediate advisory, and was based on data from the Air Force Reserve reconnaissance aircraft that was in the storm through midday. The initial wind speed remains at that value for this advisory. The next reconnaissance mission is scheduled to investigate Lee this evening. The early aircraft data along with a couple of fortuitous ASCAT overpasses showed that the wind field of Lee has continued to expand. The 50-kt wind radii extend outward up to 170 n mi over the eastern semicircle of the storm. NOAA buoy 41048 located about 75 miles (120 km) west of the center of Lee has recently reported a peak one-minute sustained wind of 58 kt and a gust to 76 kt and wave heights of around 30 ft. Bermuda, located more than 220 miles east-northeast of the center has also reported sustained tropical-storm force winds today. Lee is moving northward at about 13 kt, which is slightly faster than before. Lee should continue to pick up some forward speed as it moves northward around the western side of a mid-level ridge over the central Atlantic during the next 12-24 hours. After that time a slight bend to the north-northwest is likely late Friday or early Saturday, and this motion should bring the center of Lee near or over southwestern Nova Scotia late Saturday. After that time, Lee is forecast to turn northeastward over Atlantic Canada. The track guidance is still in good agreement, and no significant changes to the previous official forecast were required. Increasing southwesterly vertical wind shear and dry air entrainment could cause some additional weakening, but baroclinic forcing during the early stages of Lee`s extratropical transition may help to maintain the cyclone`s intensity through Friday. By Friday night Lee will be moving over significantly cooler sea surface temperatures, and gradual weakening is expected after that time. Lee is forecast to complete its transition into an extratropical cyclone when it nears Atlantic Canada. Regardless of Lee`s designation when it approaches New England and Atlantic Canada, it will remain a very large and dangerous cyclone through landfall. KEY MESSAGES: 1. Tropical storm conditions, heavy rainfall, and high surf will continue to impact Bermuda through Friday morning, and a Tropical Storm Warning is in effect for the island. 2. Hurricane conditions and coastal flooding are possible in portions of eastern Maine, southern New Brunswick, and western Nova Scotia on Saturday, and a Hurricane Watch is in effect for that area. Tropical storm conditions and coastal flooding are expected to begin in southern New England on Friday afternoon, and spread northward along the coast of New England through Saturday where Tropical Storm warnings are in effect. 3. Heavy rainfall from Lee may produce localized urban and small stream flooding across eastern New England and into portions of New Brunswick and Nova Scotia from Friday night into Saturday night. FORECAST POSITIONS AND MAX WINDS INIT 14/2100Z 31.7N 68.3W 75 KT 85 MPH 12H 15/0600Z 33.8N 67.9W 75 KT 85 MPH 24H 15/1800Z 37.0N 66.9W 75 KT 85 MPH 36H 16/0600Z 40.3N 66.6W 70 KT 80 MPH 48H 16/1800Z 43.3N 66.4W 60 KT 70 MPH...POST-TROP/EXTRATROP 60H 17/0600Z 46.0N 65.0W 45 KT 50 MPH...POST-TROP/EXTRATROP 72H 17/1800Z 48.6N 61.4W 40 KT 45 MPH...POST-TROP/EXTRATROP 96H 18/1800Z 53.7N 48.0W 35 KT 40 MPH...POST-TROP/EXTRATROP 120H 19/1800Z...DISSIPATED $$ Forecaster Brown |