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| #1105972 (Received by flhurricane at: 4:41 AM 06.Sep.2022) TCDAT5 Hurricane Danielle Discussion Number 21 NWS National Hurricane Center Miami FL AL052022 900 AM GMT Tue Sep 06 2022 Danielle`s cloud pattern has degraded further this morning by shedding its curved bands in the eastern semicircle. The remaining outer bands have become more fragmented with cloud top temperatures of only -47C. Dvorak final-T numbers are on the decline, and a compromise of both TAFB`s and SAB`s intensity estimates, along with the UW-CIMSS objective assessment, supports lowering the initial intensity to 65 kt for this advisory. Although Danielle is currently moving over relatively warm (25C) oceanic surface temperatures, the cyclone should begin to lose its tropical characteristics soon as it traverses cooler SSTs of less than 22C during the next day or two. Guidance continues to indicate that Danielle will complete its extratropical transition on Thursday, although the vertical thermal structure shows the system sustaining its warm core above 600 mb. Over the weekend, deterministic cyclone phase analyses, and simulated IR predictions show Danielle, as the dominant system, merging with a baroclinic system approaching from the west. A warm seclusion structure develops while the system occludes, or is cut-off north of the mid-latitude westerlies. The NHC intensity forecast is similar to the previous advisory and continues to lean toward the IVCN intensity consensus model. The initial motion is estimated to be northeastward at 7 kt, and Danielle should continue moving in this heading through this evening. Afterward, a turn toward the east-northeast by early Wednesday, while accelerating, is anticipated. By the early weekend, the cyclone is expected to interact with a baroclinic system by rotating cyclonically north of the westerlies and becoming a vastly larger extratropical low well west of the British Isles. Once merged into one large, storm-force extratropical low, the system should commence a general motion toward the east-southeast on Sunday. Danielle is producing huge seas over the central-north Atlantic. Complete information on the High Seas Forecasts can be found at the Ocean Prediction Center under AWIPS header NFDHSFAT1, WMO header FZNT01 KWBC, and online at ocean.weather.gov/shtml/NFDHSFAT1.php. FORECAST POSITIONS AND MAX WINDS INIT 06/0900Z 42.1N 41.9W 65 KT 75 MPH 12H 06/1800Z 42.5N 40.7W 65 KT 75 MPH 24H 07/0600Z 43.3N 38.4W 65 KT 75 MPH 36H 07/1800Z 44.7N 35.6W 60 KT 70 MPH 48H 08/0600Z 46.5N 32.9W 60 KT 70 MPH 60H 08/1800Z 48.6N 31.4W 55 KT 65 MPH...POST-TROP/EXTRATROP 72H 09/0600Z 50.3N 31.6W 50 KT 60 MPH...POST-TROP/EXTRATROP 96H 10/0600Z 49.1N 32.4W 45 KT 50 MPH...POST-TROP/EXTRATROP 120H 11/0600Z 46.5N 25.4W 40 KT 45 MPH...POST-TROP/EXTRATROP $$ Forecaster Roberts |
