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Hurricane Larry Forecast Discussion Number 20
2021-09-05 16:45:32| National Hurricane Center (Atlantic)
Issued at 1100 AM AST Sun Sep 05 2021 000 WTNT42 KNHC 051445 TCDAT2 Hurricane Larry Discussion Number 20 NWS National Hurricane Center Miami FL AL122021 1100 AM AST Sun Sep 05 2021 Larry continues as a large and intense hurricane this morning, with a 40 n mi diameter eye surround by cloud tops to near -80 deg C. There are, however, some breaks in the cold tops over the northern portion of the circulation. The current intensity is adjusted slightly to 110 kt, based on a blend of subjective Dvorak estimates from TAFB and SAB along with objective ADT estimates from UW-CIMSS. Upper-level outflow remains somewhat restricted over the southwestern quadrant of the system, indicative of at least slight vertical shear. This shear is probably being caused by the flow to the east of an upper-level low to the north of Puerto Rico. The low is forecast to move northwestward over the next few days, possibly lessening the shear over Larry. The hurricane is moving northwestward at a slightly slower speed, or 310/11 kt. Larry is likely to continue its northwestward trek along the southwestern periphery of a mid-tropospheric anticyclone during the next 2-3 days, with only a slight reduction in forward speed. Around 96 hours, the hurricane is forecast to turn toward the north-northwest and north while rounding the western side of the ridge. By the end of the forecast period, Larry is expected to begin its recurvature into the mid-latitude westerlies. The new official forecast track essentially follows the previous one, and is also very close to the latest NOAA corrected consensus and Florida State University Superensemble guidance. Larry's large eye suggests that no rapid changes in strength are likely during the short term. Since vertical shear is not expected to increase and the system will be traversing warm waters, the hurricane should be able to more or less maintain its intensity during the next few days. One inhibiting factor is the presence of relatively dry mid-level air in the environment. The official intensity forecast is on the high side of the model guidance and keeps Larry as a major hurricane through 72 hours. Key Messages: 1. Large swells generated by Larry are expected to reach the Lesser Antilles today and will spread to portions of the Greater Antilles, the Bahamas, and Bermuda on Monday and Tuesday. Significant swells will likely reach the east coast of the United States and Atlantic Canada by midweek. 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 advice of lifeguards and local officials this week. 2. Larry is forecast to approach Bermuda during the next several days, likely as a major hurricane, bringing a risk of strong winds, heavy rainfall, and coastal flooding to the island by the middle of this week. While it is too soon to determine the magnitude of these hazards and potential impacts on Bermuda, interests there should closely monitor the latest forecast updates during the next several days. FORECAST POSITIONS AND MAX WINDS INIT 05/1500Z 19.5N 49.7W 110 KT 125 MPH 12H 06/0000Z 20.5N 51.1W 110 KT 125 MPH 24H 06/1200Z 21.9N 52.7W 110 KT 125 MPH 36H 07/0000Z 23.0N 54.0W 110 KT 125 MPH 48H 07/1200Z 24.3N 55.4W 105 KT 120 MPH 60H 08/0000Z 25.7N 56.7W 105 KT 120 MPH 72H 08/1200Z 27.3N 58.1W 105 KT 120 MPH 96H 09/1200Z 31.1N 61.1W 95 KT 110 MPH 120H 10/1200Z 37.4N 60.6W 85 KT 100 MPH $$ Forecaster Pasch
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