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Tropical Storm Barry Forecast Discussion Number 9
2019-07-12 16:48:43| National Hurricane Center (Atlantic)
Issued at 1000 AM CDT Fri Jul 12 2019 000 WTNT42 KNHC 121448 TCDAT2 Tropical Storm Barry Discussion Number 9 NWS National Hurricane Center Miami FL AL022019 1000 AM CDT Fri Jul 12 2019 Reports from Air Force Reserve and NOAA Hurricane Hunter aircraft indicate that Barry has strengthened during the past several hours. The Air Force plane reported maximum 850-mb flight-level winds of 62 kt and reliable-looking SFMR winds of 50-55 kt in the strong convection that has developed in the southern quadrant. In addition, the data from both planes indicate the central pressure has fallen to near 998 mb. Based on these data, the initial intensity is increased to 55 kt. Data from the NOAA plane, which is flying near 460 mb, shows that the center at that level is south of the low-level center, likely due to ongoing northerly shear. The initial motion is an erratic 290/4. While there is still a larger than normal spread between the UKMET on the left side and the HWRF on the right side, the track guidance has come into better agreement that Barry will turn northwestward later today or tonight, with this motion continuing until the center makes landfall along the Louisiana coast in 24-30 h. After landfall, the system should move northward through a break in the ridge of high pressure over the United States until the 72 h point, after which it should recurve northeastward into the westerlies. The new track forecast has only minor tweaks from the previous forecast, and it lies near the various consensus models. Barry has been strengthening despite an asymmetric convective structure, ongoing northerly shear, and the presence of mid- to upper-level dry air over the northern semicircle. The intensity guidance suggests that, while the environment will be at best marginally favorable, the cyclone will continue to intensify until landfall. Based on this, the new intensity forecast calls for Barry to become a hurricane in 24 h, just before landfall, with this forecast being slightly above the guidance. After landfall, the cyclone should steadily weaken, with decay to a remnant low forecast to occur in about 72 h. Key Messages: 1. There is a danger of life-threatening storm surge inundation along the coast of southern and southeastern Louisiana, portions of Lake Pontchartrain, and portions of coastal Mississippi where a Storm Surge Warning is in effect. Water levels are already beginning to rise in these areas, with the peak inundation expected on Saturday. The highest storm surge inundation is expected between Intracoastal City and Shell Beach. 2. The slow movement of Barry will result in a long duration heavy rainfall and flood threat along the central Gulf Coast, across portions of the Lower Mississippi Valley and north into the Tennessee Valley through the weekend into early next week. Flash flooding and river flooding will become increasingly likely, some of which may be life-threatening, especially across portions of southeast Louisiana into Mississippi. 3. Hurricane conditions are expected along a portion of the coast of Louisiana, where a Hurricane Warning is in effect. Tropical storm conditions are expected elsewhere along much of the Louisiana coast and inland across portions of south-central Louisiana where tropical storm warnings are in effect. FORECAST POSITIONS AND MAX WINDS INIT 12/1500Z 28.2N 90.4W 55 KT 65 MPH 12H 13/0000Z 28.6N 90.9W 60 KT 70 MPH 24H 13/1200Z 29.4N 91.5W 65 KT 75 MPH 36H 14/0000Z 30.5N 92.0W 45 KT 50 MPH...INLAND 48H 14/1200Z 31.8N 92.4W 30 KT 35 MPH...INLAND 72H 15/1200Z 34.4N 92.4W 20 KT 25 MPH...POST-TROP/REMNT LOW 96H 16/1200Z 37.0N 90.5W 20 KT 25 MPH...POST-TROP/REMNT LOW 120H 17/1200Z 39.5N 87.0W 20 KT 25 MPH...POST-TROP/REMNT LOW $$ Forecaster Beven
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