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| #1197369 (Received by flhurricane at: 5:09 AM 09.Sep.2024) TCDAT1 Potential Tropical Cyclone Six Discussion Number 3 NWS National Hurricane Center Miami FL AL062024 400 AM CDT Mon Sep 09 2024 Satellite imagery shows that the disturbance is producing considerable deep convection with cloud tops colder than -70 deg C. However, the cloud pattern is still in the organizing stage with not much evidence of banding features at this time. Upper-level outflow is becoming established over the area. Observations from an Air Force reconnaissance aircraft, data buoy 42055, and a partial ASCAT overpass suggest that the system has not yet developed a well- defined center of circulation. The intensity is held at 45 kt for this advisory with the assumption of some undersampling of the winds over the western part of the circulation. However, this could be generous. Since the center is still not well defined, the initial motion is a rather uncertain, but slow, 340/4 kt. During the next day or so, the system is expected to move along the western side of a mid-level ridge over the Gulf of Mexico. This motion should keep the core of the system off the coast of northeastern Mexico and southern Texas for the next 24-36 hours. Then, a shortwave trough over Texas is expected to induce a turn toward the northeast with an increase in forward speed, which would take the center of the system near and across the northwestern or northern Gulf coast late Wednesday. The official track forecast has again been nudged eastward in the 48-72 hour period, but not quite as far east as the ECMWF and corrected consensus model predictions. It should be noted that confidence in the track forecast is lower than normal since the system lacks a well-defined center. Since the system is still not very well-organized and lacks an inner core structure, only slow strengthening is expected through this morning. However, the disturbance is expected to soon become better organized while remaining over very warm waters, with high low- to mid-tropospheric humidity, and low vertical shear for the next 48 hours. Therefore steady strengthening is likely to begin by later today. This is also shown by most of the numerical guidance. When the system nears landfall, the global models show increasing upper-level westerlies near the northwestern Gulf coast, and this could lead to stronger vertical wind shear over the cyclone. Therefore the rate of strengthening could at least level off as the center nears the coast. The official intensity forecast is similar to the previous NHC prediction, close to the Decay-SHIPS guidance, and continues to show the system as a hurricane at landfall. KEY MESSAGES: 1. The system is forecast to become a tropical storm today as it moves near the western Gulf of Mexico coast. Tropical Storm Watches are in effect for northeastern Mexico and extreme southern Texas. 2. The system is forecast to become a hurricane before it reaches the northwestern Gulf Coast by the middle of the week. While it is too soon to pinpoint the exact location and magnitude of impacts, the potential for life-threatening storm surge and damaging winds are increasing for portions of the Louisiana and Upper Texas coastlines beginning Tuesday night. Hurricane and Storm Surge Watches will likely be issued for a portion of that area later today, and residents should ensure they have their hurricane plan in place. 3. Potential Tropical Cyclone Six is expected to bring heavy rainfall and the risk of considerable flash flooding along the coast of far northeast Mexico, portions of southernmost Texas, southern Louisiana, and southern Mississippi into Thursday morning. A risk of flash and urban flooding exists across portions of the Mid-South from Wednesday into Friday morning. FORECAST POSITIONS AND MAX WINDS INIT 09/0900Z 22.2N 94.8W 45 KT 50 MPH...POTENTIAL TROP CYCLONE 12H 09/1800Z 23.0N 95.3W 45 KT 50 MPH...TROPICAL CYCLONE 24H 10/0600Z 24.1N 95.9W 55 KT 65 MPH 36H 10/1800Z 25.2N 95.7W 60 KT 70 MPH 48H 11/0600Z 26.8N 94.8W 65 KT 75 MPH 60H 11/1800Z 28.5N 93.3W 70 KT 80 MPH 72H 12/0600Z 30.7N 91.8W 50 KT 60 MPH...INLAND 96H 13/0600Z 34.9N 90.2W 30 KT 35 MPH...POST-TROPICAL 120H 14/0600Z 37.5N 89.0W 20 KT 25 MPH...POST-TROPICAL $$ Forecaster Pasch |
