{"id": "1217359894665396231", "title": "Tropical Cyclone Discussion", "adv_date": "2026-10-09T21:00:00Z", "msg": "981\nWTNT44 KNHC 092052\nTCDAT4\n \nHurricane Isaias Discussion Number  13\nNWS National Hurricane Center Miami FL       AL092026\n400 PM CDT Fri Oct 09 2026\n \nDeep-layer shear from the southwest has increased to 30-40 kt, and\nthe hurricane's structure is responding accordingly. WSR-88D radar\ndata shows that the structure is becoming increasingly asymmetric,\nwith very intense convection mainly confined to the northern\neyewall. Tail Doppler radar data from the NOAA P-3 has also shown\nthat the circulation is becoming tilted with height. That said,\nsome impressive winds were measured at flight-level--136 kt by the\nAir Force Reserve at 10,000 feet and 126 kt by NOAA at 8,000 ft.\nWhile these winds themselves would normally support a higher\nintensity, several dropsondes released in the eyewall showed that\nthere is a sharp drop-off of winds at the ocean surface, with\nlayer-averaging suggesting a surface intensity of 90-95 kt. In\naddition, recent Doppler radar data from Mobile show winds of\n100-110 kt at about 10,000 feet in the northern eyewall. Combining\nall this data together, the maximum surface winds appear to be\naround 100 kt, although it's very likely that Isaias will be a\ngustier-than-normal hurricane when it makes landfall.\n \nIsaias has turned northward and is accelerating with a current\nmotion of 010/15 kt. The track guidance has honed in on a landfall\nover the western Florida Panhandle near the Pensacola area sometime\nthis evening. A northward motion is expected to continue through\nSaturday, bringing Isaias's center through Alabama, followed by a\nnortheastward trajectory across the Tennessee and the central\nAppalachians on Sunday. The circulation is expected to dissipate by\nhour 60.\n \nThe high-resolution hurricane regional models (HAFS-A, HAFS-B, and\nHWRF), as well as the statistical-dynamical models (SHIPS and LGEM)\nindicate that Isaias is likely to be at or near major hurricane\nstrength at landfall this evening. After landfall, fast weakening\nis expected, with some caveats. As mentioned previously, Isaias is\nlikely to be a gusty hurricane, and its fast motion could bring\nstrong hurricane-force gusts well inland. Simulated satellite\nimagery from global model guidance indicates that Isaias is likely\nto transition to a post-tropical cyclone over Alabama by Saturday\nafternoon, although it could still be producing\ntropical-storm-force gusts, especially in areas of higher terrain.\n \n \nKey Messages:\n \n1. A life-threatening storm surge is expected from the Mouth of the\nMississippi River to Suwannee, Florida. Residents under evacuation\norders should leave immediately and follow advice from local\nofficials.\n \n2. Extremely dangerous and damaging hurricane force-winds are\nexpected over portions of the Florida Panhandle, southern Alabama,\nand southern Mississippi where a Hurricane Warning is in effect.\nResidents in these areas should have a safe room to ride out the\nstorm and prepare for long-duration power outages.\n \n3. Damaging wind gusts are likely over a large portion of the\nsoutheastern United States from western and northern Georgia and the\nsouthern Appalachians, westward over much of central and northern\nAlabama, southern middle Tennessee, and Mississippi, especially in\nareas of higher terrain. Residents should secure loose outdoor\nitems, avoid driving high-profile vehicles, prepare for power\noutages, and be aware of the potential for falling trees.\n \n4. Isaias will bring areas of heavy rainfall to the central U.S.\nGulf coast and much of the Southeast through the weekend.\nConsiderable flash and urban flooding, along with significant river\nflooding, will be possible. Landslides are also possible across the\nSouthern Appalachians.\n \n5. The tornado potential will continue through tonight. The greatest\nrisk will be east of the center, particularly across the Florida\nPanhandle into southern Georgia. This risk will continue spreading\nnorth-northeast across parts of the Southeast on Saturday.\n \n \nFORECAST POSITIONS AND MAX WINDS\n \nINIT  09/2100Z 29.2N  87.0W  100 KT 115 MPH\n 12H  10/0600Z 31.2N  86.8W   75 KT  85 MPH...INLAND\n 24H  10/1800Z 33.4N  87.2W   40 KT  45 MPH...POST-TROP/INLAND\n 36H  11/0600Z 35.6N  86.1W   30 KT  35 MPH...POST-TROP/INLAND\n 48H  11/1800Z 38.1N  82.5W   25 KT  30 MPH...POST-TROP/INLAND\n 60H  12/0600Z...DISSIPATED\n \n"}