000 WTNT41 KNHC 100841 TCDAT1 Hurricane Earl Discussion Number 30 NWS National Hurricane Center Miami FL AL062022 500 AM AST Sat Sep 10 2022 Earl is in the first stages of extratropical transition. The convective cloud pattern is becoming stretched east to west, and the eye is rapidly losing definition while an extensive cirrus shield radiates northward away from the hurricane. Scatterometer data from last evening showed that Earl's wind field continues to expand and was beginning to merge with the strong winds behind an approaching frontal boundary. Maximum winds are still estimated to be 90 kt based on a blend of Dvorak data-T and Current Intensity numbers from TAFB and SAB, as well as the UW-CIMSS ADT. The hurricane continues to accelerate just ahead of a shortwave trough and is estimated to be moving rapidly northeastward (035 degrees) at 30 kt. However, Earl will be merging with this trough within the next 6 to 12 hours, which will cause it to slam on the brakes southeast of Newfoundland, slowing to speeds of 5 kt or less beginning tonight and continuing through Monday. After Monday, a less amplified upper-level pattern should cause the system to turn eastward and pick up some speed. The updated NHC track forecast has been shifted a bit northwestward during the first couple of days of the forecast and lies within the tightly packed guidance envelope. The NHC prediction then comes back in line with the previous forecast on days 3 through 5. The northwestward shift of the track, along with Earl's large wind field, is expected to lead to strong winds occurring over the Avalon Peninsula of Newfoundland beginning this afternoon and continuing through Sunday. For additional information on impacts in Newfoundland, please monitor forecasts and warnings from Environment Canada. Global model fields show Earl's center migrating into the cold side of the nearby frontal zone today, with extratropical transition forecast to be complete this afternoon. This process, along with Earl now crossing the tight sea surface temperature gradient north of the Gulf Stream, is expected to induce a weakening trend, with the cyclone's winds likely falling below hurricane force by tonight. Continued weakening at a more gradual pace is anticipated from Sunday onward into the middle of the week. The NHC intensity forecast most closely follows the GFS and ECMWF solutions given that Earl will soon be extratropical. KEY MESSAGES: 1. Strong winds are expected over the Avalon Peninsula of Newfoundland beginning this afternoon and continuing through Sunday, after Earl becomes a post-tropical low. 2. Large swells generated by Earl will affect Bermuda, portions of the U.S. East Coast, and Nova Scotia and Newfoundland during the next several days. These swells are likely to cause life-threatening surf and rip current conditions. Please consult products from your local weather office. FORECAST POSITIONS AND MAX WINDS INIT 10/0900Z 41.2N 53.5W 90 KT 105 MPH 12H 10/1800Z 43.2N 52.1W 75 KT 85 MPH...POST-TROP/EXTRATROP 24H 11/0600Z 44.1N 51.3W 60 KT 70 MPH...POST-TROP/EXTRATROP 36H 11/1800Z 44.5N 50.6W 50 KT 60 MPH...POST-TROP/EXTRATROP 48H 12/0600Z 44.7N 50.1W 45 KT 50 MPH...POST-TROP/EXTRATROP 60H 12/1800Z 44.8N 48.8W 40 KT 45 MPH...POST-TROP/EXTRATROP 72H 13/0600Z 44.7N 46.4W 35 KT 40 MPH...POST-TROP/EXTRATROP 96H 14/0600Z 44.9N 41.5W 35 KT 40 MPH...POST-TROP/EXTRATROP 120H 15/0600Z 45.3N 37.4W 35 KT 40 MPH...POST-TROP/EXTRATROP $$ Forecaster Berg