ZCZC MIATCDAT3 ALL TTAA00 KNHC DDHHMM Hurricane Lee Discussion Number 39 NWS National Hurricane Center Miami FL AL132023 1100 PM AST Thu Sep 14 2023 Observations from an Air Force Reserve Unit Hurricane Hunter aircraft indicate that Lee's eyewall is not well defined, and this is also suggested by geostationary satellite and microwave imagery. Although the peak 700 mb flight-level winds reported by the plane were near 93 kt, the highest SFMR-observed surface winds were 72 kt. Thus the winds aloft in the hurricane are not being transported very effectively to the surface. This is not surprising, since the central deep convection is no longer very strong. The current intensity is kept at 75 kt based on the aircraft data, which is well above the Dvorak satellite estimates. Lee wobbled a bit to the northeast early this evening, but the longer-term motion appears to be just east of north, or around 010/12 kt. The system should move generally northward at a faster forward speed, on the west side of a mid-level ridge, during the next day or so. A slight bend to the left is likely late Friday as the cyclone interacts with a mid-level trough. By late Saturday, Lee should begin to turn toward the north-northeast with the center passing near or over western Nova Scotia. Then, Lee is forecast to turn northeastward over Atlantic Canada. The track guidance remains in good agreement through 72 hours, and the official forecast is basically an update of the previous one. South-southwesterly shear is predicted to increase significantly over Lee during the next couple of days. This, along with cooler SSTs, particularly after the system moves north of 40N latitude, should result in weakening. However, baroclinic processes could help the cyclone maintain its intensity, or at least slow the weakening rate. The official intensity forecast is above the model guidance for this reason. In 48 hours, simulated satellite imagery shows an asymmetric cloud structure characteristic of an extratropical cyclone. Regardless of when extratropical transition actually occurs, however, Lee should 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 and over portions of Atlantic Canada 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 15/0300Z 32.9N 67.6W 75 KT 85 MPH 12H 15/1200Z 35.0N 67.3W 75 KT 85 MPH 24H 16/0000Z 38.4N 66.6W 75 KT 85 MPH 36H 16/1200Z 41.6N 66.6W 65 KT 75 MPH 48H 17/0000Z 44.3N 66.0W 60 KT 70 MPH...POST-TROP/INLAND 60H 17/1200Z 47.0N 63.6W 45 KT 50 MPH...POST-TROP/EXTRATROP 72H 18/0000Z 49.6N 59.1W 40 KT 45 MPH...POST-TROP/EXTRATROP 96H 19/0000Z 54.5N 42.5W 35 KT 40 MPH...POST-TROP/EXTRATROP 120H 20/0000Z...DISSIPATED $$ Forecaster Pasch NNNN