Tropical Storm Gordon Discussion Number 8

Tropical Storm Gordon Discussion Number 8 NWS National Hurricane Center Miami FL AL072018 400 AM CDT Tue Sep 04 2018 Gordon has changed little in organization on geostationary satellite images or on the WSR-88D radar presentation over the past several hours. The storm has a small CDO with convective banding features primarily over the eastern semicircle of the circulation. Overall the cloud pattern is indicative of moderate westerly shear over the system, likely associated with an upper-level trough near the central Gulf of Mexico. An Air Force Reserve Unit Hurricane Hunter aircraft investigated Gordon a few hours ago and reported maximum SFMR-measured surface winds of 54 kt. On this basis the intensity had been adjusted to 55 kt, which is somewhat above the latest Dvorak estimates. It is assumed that the shear will not be strong enough to inhibit at least some strengthening before landfall, so the tropical cyclone is still forecast to become a hurricane later today. The official forecast, prior to landfall, is close to the latest LGEM intensity guidance, and near the upper end of the guidance suite. Gordon should weaken rapidly after landfall in the lower Mississippi Valley region. The motion continues west-northwestward, or 300/15 kt. There is little or no change to the NHC track prediction or forecast reasoning from the previous advisory. Gordon is expected to move along the southwestern periphery of a mid-level high pressure area and make landfall along the north-central Gulf of Mexico coast within 24 hours. After landfall, the cyclone is forecast to move northwestward, along the western side of the high, at a reduced forward speed. Late in the forecast period Gordon, or its post-tropical remnant, should turn northward to north-northeastward as it approaches the mid-latitude westerlies. The official track forecast is near the model consensus and very close to the previous NHC track. Key Messages: 1. Gordon is expected to bring life-threatening storm surge and hurricane conditions to portions of the central Gulf Coast where a Storm Surge Warning and Hurricane Warning are in effect. Residents in these areas should listen to advice from their local officials. All preparations to protect life and property should be rushed to completion, as tropical storm conditions are expected to arrive in the warning areas this afternoon. 2. Heavy rainfall from Gordon will affect the western Florida Panhandle, southern Alabama, southern Mississippi and Louisiana, where totals could reach as high as 12 inches. This rainfall could cause flash flooding.