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| #1060526 (Received by flhurricane at: 11:00 PM 06.Sep.2021) TCDAT2 Hurricane Larry Discussion Number 26 NWS National Hurricane Center Miami FL AL122021 1100 PM AST Mon Sep 06 2021 Larry has changed little in geostationary satellite imagery since the NOAA P-3 aircraft left the storm after 2130 UTC. Data from the mission showed that the hurricane possessed a very large wind field, and there were occasional hints in the flight-level wind data of an outer wind maxima trying to develop. The most recent passive microwave imagery from a 2148 UTC SSMIS pass showed some evidence of secondary bands forming away from the primary eyewall, though the inner eye remains large and distinct. Whether or not this will be the start of another eyewall replacement cycle (ERC) remains to be seen. For now, both the subjective Dvorak estimates from SAB and TAFB remain unchanged from earlier today, so Larry`s intensity has been maintained at 110 kt for this advisory. The hurricane continues to move to the northwest at 325/9 kt, guided along the southwestern periphery of a prominent subtropical ridge. Larry will reach the westward extent of this ridge in 60-72 hours as a large deep-layer trough approaches from the northeastern United States. The latest guidance now shows this trough capturing Larry towards the end of the forecast period, resulting in an abrupt acceleration to the northeast as the hurricane is steered by the strong westerly flow ahead of the mid-latitude trough. The track guidance continues to be in great agreement with Larry`s forecast track, and only a few minor adjustments were needed to the most recent forecast, staying near the middle of the track guidance envelope. This latest forecast continues to show Larry passing to the east of Bermuda on Thursday. However, given Larry`s large size, some impacts could still be felt even if the center passes well east, and a tropical storm watch could be needed for the island as soon as tomorrow morning. The intensity forecast for Larry over the next few days is likely to be controlled by changes to its inner-core structure. If another ERC begins soon, this could result in a short-term drop off in maximum sustained winds as the hurricane`s wind field expands. As mentioned last night, the broadening wind field, in combination with Larry`s slow motion currently at 9 kt, could also result in more ocean upwelling closer to Larry`s inner core. While the latest SHIPS guidance depicts warm sea-surface temperatures along the track of Larry over the next 2-3 days, the oceanic heat content in this part of the Atlantic basin is not very high. This might explain why the atmosphere-ocean coupled models (COAMPS-TC, HWRF, HAFS-B) show more significant weakening with a gradually decaying inner-core over cooler upwelled waters. The latest NHC intensity forecast is lower than the previous one, giving a bit more weight to the dynamically coupled hurricane models versus the statistical-dynamical guidance. However, even this latest forecast is higher than the reliable HFIP Corrected Consensus Approach (HCCA). Regardless of these intensity details, Larry is expected to remain a large and powerful hurricane over the next few days. Key Messages: 1. Large swells generated by Larry are affecting the Lesser Antilles and will spread to portions of the Greater Antilles, the Bahamas, and Bermuda tonight and tomorrow. Significant swells should reach the east coast of the United States and Atlantic Canada by midweek and continue affecting these shores through the end of the week. These swells will likely cause life-threatening surf and rip current conditions, and beachgoers and other interests along these coasts are urged to follow the guidance of lifeguards and local officials this week. 2. Larry is forecast to approach Bermuda during the next few days as a large and powerful hurricane, bringing a risk of strong winds, heavy rainfall, and coastal flooding to the island by the middle of this week. Interests in Bermuda should closely monitor the latest forecast updates during the next few days, and tropical storm watches could be needed for the island as soon as tomorrow. FORECAST POSITIONS AND MAX WINDS INIT 07/0300Z 23.1N 54.4W 110 KT 125 MPH 12H 07/1200Z 24.1N 55.5W 105 KT 120 MPH 24H 08/0000Z 25.6N 56.8W 100 KT 115 MPH 36H 08/1200Z 27.3N 58.2W 95 KT 110 MPH 48H 09/0000Z 29.2N 59.9W 95 KT 110 MPH 60H 09/1200Z 31.6N 61.3W 90 KT 105 MPH 72H 10/0000Z 34.6N 61.8W 90 KT 105 MPH 96H 11/0000Z 44.0N 55.7W 80 KT 90 MPH 120H 12/0000Z 55.5N 43.4W 65 KT 75 MPH...POST-TROP/EXTRATROP $$ Forecaster Papin |