Post-Tropical Cyclone Elsa Forecast Discussion Number 38
ActuCyclone
9 juillet 2021
000 WTNT45 KNHC 091446 TCDAT5 Tropical Storm Elsa Discussion Number 38 NWS National Hurricane Center Miami FL AL052021 1100 AM EDT Fri Jul 09 2021 The extratropical transition of Elsa is well underway. A frontal boundary located over southern New England nearly wraps into the circulation center, and the primary area of cold cloud tops and heavy rainfall has now shifted to the northwestern portion of the cyclone. Elsa is expected to complete its extratropical transition this afternoon. Buoy and surface observations indicate that the cyclone's intensity has changed little since early this morning. Based on those data, Elsa's peak winds and minimum pressure remain 45 kt and 1000 mb for this advisory, respectively. Elsa continues to move quickly northeastward or 045/27 kt. The post-tropical cyclone is forecast to continue accelerating northeastward over the next day or two as it remains embedded within deep-layer southwesterly flow. After 48 hours, the system is expected to slow before it dissipates over the north Atlantic around day 3. The track guidance remains in good agreement, but has shifted slightly southward after 24 hours and the NHC forecast has been adjusted accordingly. Little change in strength is anticipated in the short-term as Elsa completes its extratropical transition. After that time, gradual weakening is anticipated and the wind speed forecast calls for the system to weaken below gale-force in a couple of days. The global models show the post-tropical cyclone dissipating over the north Atlantic by early next week, and the official forecast follows suit. Key Messages: 1. As Elsa moves near southern and coastal New England today, heavy rainfall could lead to considerable flash and urban flooding. 2. Tropical storm conditions are expected to continue in portions of the warning area in Long Island and southern New England through this afternoon. Gusty winds are expected over portions of Atlantic Canada tonight and Saturday. FORECAST POSITIONS AND MAX WINDS INIT 09/1500Z 41.0N 72.1W 45 KT 50 MPH 12H 10/0000Z 44.0N 67.7W 45 KT 50 MPH...POST-TROP/EXTRATROP 24H 10/1200Z 48.4N 60.3W 40 KT 45 MPH...POST-TROP/EXTRATROP 36H 11/0000Z 52.2N 51.0W 35 KT 40 MPH...POST-TROP/EXTRATROP 48H 11/1200Z 56.5N 41.0W 30 KT 35 MPH...POST-TROP/EXTRATROP 60H 12/0000Z 60.0N 32.5W 30 KT 35 MPH...POST-TROP/EXTRATROP 72H 12/1200Z...DISSIPATED $$ Forecaster Brown