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Hurricane Laura Forecast Discussion Number 26
2020-08-26 10:58:21| National Hurricane Center (Atlantic)
Issued at 400 AM CDT Wed Aug 26 2020 000 WTNT43 KNHC 260858 TCDAT3 Hurricane Laura Discussion Number 26 NWS National Hurricane Center Miami FL AL132020 400 AM CDT Wed Aug 26 2020 Satellite images indicate that Laura has become a formidable hurricane since yesterday evening. Deep convection has intensified and become more symmetric, with an eye now trying to clear out. An earlier Air Force Hurricane Hunter mission found flight-level winds of 104 kt, along with peak SFMR values of 86 kt, which supported the 90-kt intensity on the intermediate advisory. Since that time, however, the cloud pattern has only continued to improve, so the initial wind speed is set to 95 kt for this advisory. Notably, the aircraft also recorded that the extent of the hurricane-force winds have increased substantially northeast of the center. A pair of Hurricane Hunter planes should be in the area within a couple of hours. The hurricane has intensified a remarkable 40 kt during the past 24 hours, and there are no signs it will stop soon, with shear remaining low-to-moderate over the deep warm waters of the central Gulf of Mexico. Guidance is noticeably higher than before, so the new peak intensity will be raised to 115 kt, and some models are even a little higher. Increasing shear is expected to slightly weaken the hurricane close to landfall, so the new forecast keeps the previous 105-kt intensity near the coast. Laura will weaken rapidly after landfall, but it will likely bring hurricane-force winds well inland over western Louisiana and eastern Texas. In the extended range, there is some chance that Laura re-intensifies as a tropical cyclone off the Mid-Atlantic coast, instead of becoming part of a frontal system, but for now the forecast will stay extratropical at 96 hours and beyond. Recent satellite shows that Laura has turned northwestward, now estimated at 13 kt. There are no substantial changes to the track forecast to report. The hurricane should gradually turn toward the northwest and north over the next day or two as it moves around the western periphery of a mid-level high. The models are in very good agreement on the center of Laura moving into extreme southwestern Louisiana or southeastern Texas in about 24 hours, so no changes were made to the previous NHC forecast. Later in the forecast period the weakened cyclone should turn toward the east-northeast and move with increasing forward speed while embedded within the mid-latitude westerlies. The official track forecast is shifted southward at longer range, not too far from the latest consensus track model predictions. It should be mentioned Laura is now a large hurricane, and wind, storm surge, and rainfall hazards will extend far from the center. Do not use the cone graphic for any representation of these hazards, it is just for the center uncertainty. Key Messages: 1. Life-threatening storm surge with large and dangerous waves is expected to produce potentially catastrophic damage from San Luis Pass, Texas, to the Mouth of the Mississippi River, including areas inside the Port Arthur Hurricane Flood Protection system. This surge could penetrate up to 30 miles inland from the immediate coastline in southwestern Louisiana and southeastern Texas. Actions to protect life and property should be rushed to completion as water levels will begin to rise later today. 2. Hurricane-force winds are expected tonight in the warning area from San Luis Pass, Texas, to west of Morgan City, Louisiana, and the strongest winds associated with Laura's eyewall will occur somewhere within this area. Hurricane-force winds and widespread damaging wind gusts are also expected to spread well inland into portions of eastern Texas and western Louisiana early Thursday. 3. Widespread flash flooding along small streams, urban areas, and roadways is expected to begin this afternoon into Thursday from far eastern Texas, across Louisiana and Arkansas. This will also lead to minor to isolated moderate freshwater river flooding. The heavy rainfall threat and localized flash and urban flooding potential will spread northeastward into the middle-Mississippi, lower Ohio and Tennessee Valleys Friday night and Saturday. FORECAST POSITIONS AND MAX WINDS INIT 26/0900Z 26.1N 90.7W 95 KT 110 MPH 12H 26/1800Z 27.4N 92.4W 115 KT 130 MPH 24H 27/0600Z 29.7N 93.5W 105 KT 120 MPH...NEAR COAST 36H 27/1800Z 32.4N 93.7W 50 KT 60 MPH...INLAND 48H 28/0600Z 34.8N 92.9W 30 KT 35 MPH...INLAND 60H 28/1800Z 36.4N 91.0W 25 KT 30 MPH...INLAND 72H 29/0600Z 37.3N 87.3W 30 KT 35 MPH...INLAND 96H 30/0600Z 38.0N 74.5W 35 KT 40 MPH...POST-TROP/EXTRATROP 120H 31/0600Z 44.0N 60.0W 45 KT 50 MPH...POST-TROP/EXTRATROP $$ Forecaster Blake
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