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| #1108242 (Received by flhurricane at: 4:51 PM 21.Sep.2022) TCDAT2 Hurricane Fiona Discussion Number 30 NWS National Hurricane Center Miami FL AL072022 500 PM EDT Wed Sep 21 2022 Fiona continues to have a fairly impressive presentation on satellite images, although the eye has become partially cloud- filled. The central convection continues to have very cold cloud tops to near -80 deg C, and the Central Dense Overcast is surrounded by numerous banding features, especially over the eastern semicircle. Upper-tropospheric outflow is strong over the northern and eastern portions of the circulation. The current intensity is held at 115 kt, i.e. Category 4, in agreement with a subjective Dvorak estimate from SAB. The hurricane should remain over warm waters for the next 48 hours, and in a moist and unstable air mass. Some strengthening is still possible within the next day or so. Eyewall replacement cycles could cause some intensity fluctuations, but these are difficult to predict. Fiona is expected to interact with a strong mid-tropospheric trough moving off the northeastern United States coast in around 60 hours. This interaction should lead to the system transforming into an intense extratropical cyclone, with hurricane-force winds, before it reaches Atlantic Canada. Fiona`s motion is beginning to show signs of a turn toward the north-northeast as the eye has been leaning toward the right over the past few hours. The initial motion is just east of north or about 010/8 kt. There are no significant changes to the track forecast or its reasoning. During the next 12 to 24 hours, the hurricane is expected to move northward to north-northeastward along the western periphery of a mid-level subtropical high pressure area. Thereafter, Fiona is forecast to gradually accelerate northeastward to north-northeastward in the flow ahead of the aforementioned trough. The official track forecast remains close to both the simple and corrected dynamical model consensus, TVCN and HCCA, respectively. Based on an earlier ASCAT overpass, the wind radii have been expanded. The model guidance indicates that Fiona will grow even larger in size during the next few days. Key Messages: 1. Hurricane conditions are possible, and tropical storm conditions are expected, on Bermuda by late tomorrow. 2. Fiona is expected to affect portions of Atlantic Canada as a powerful hurricane-force cyclone late Friday and Saturday, and could produce significant impacts from high winds, storm surge, and heavy rainfall. Interests in these areas should closely monitor the progress of Fiona and updates to the forecast. FORECAST POSITIONS AND MAX WINDS INIT 21/2100Z 25.6N 71.5W 115 KT 130 MPH 12H 22/0600Z 27.0N 71.0W 120 KT 140 MPH 24H 22/1800Z 29.5N 69.6W 120 KT 140 MPH 36H 23/0600Z 32.6N 66.9W 115 KT 130 MPH 48H 23/1800Z 37.4N 63.0W 110 KT 125 MPH 60H 24/0600Z 43.5N 61.1W 90 KT 105 MPH...POST-TROP/EXTRATROP 72H 24/1800Z 47.0N 61.0W 75 KT 85 MPH...POST-TROP/EXTRATROP 96H 25/1800Z 52.5N 60.5W 45 KT 50 MPH...POST-TROP/EXTRATROP 120H 26/1800Z 60.0N 59.1W 35 KT 40 MPH...POST-TROP/EXTRATROP $$ Forecaster Pasch |
