Area Forecast Discussion
Issued by NWS Huntsville, AL

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000 FXUS64 KHUN 150409 AFDHUN Area Forecast Discussion National Weather Service Huntsville AL 1109 PM CDT Fri Aug 14 2020 .UPDATE... For 06Z TAFS. && .NEAR TERM...(Rest of tonight) Issued at 942 PM CDT Fri Aug 14 2020 Warm upper level ridging remained over the Desert SW, while upper troughing was amplifying over eastern CONUS. A weak upper level low within the troughing over the IN/OH border had trough extending towards the Tennessee Valley. A vorticity maxima over western Tennessee featured an area of showers and thunderstorms, moving to the SE. This activity per the new NAM, along with hourly updates from the RAP and HRRR had it gradually dissipating as it nears the forecast area - with it generally gone after 2-3 AM. Given uncertainty with this convection, left rain chances as is for tonight. Will revisit this and raise rain chances for our NE areas if the storms and other newer guidance keeps it going. The rest of the forecast output looked okay for now. .SHORT TERM...(Saturday through Sunday night) Issued at 242 PM CDT Fri Aug 14 2020 Much of the central and western part of the forecast area may be completely dry on Saturday in the wake of the trough passage. Our eastern counties may experience a few more showers and thunderstorms, mainly through early afternoon. However, coverage should not be widespread. With afternoon mixing, dew points should lower below 70 degrees in many areas. The more noticeably airmass change will occur after a cold front drops southeast on Sunday. So, one more muggy day is expected just ahead of the front Sunday. Isolated thunderstorms are possible, but with a more limited deep moisture profile and generally weak QG forcing, will keep PoPs/coverage more limited. Will not rule out a strong storm or two, but this doesn`t appear to be a linear/widespread convective event. Noticeably drier air will arrive by Monday morning when lows should dip into the 60s areawide except near the larger lakes still retaining warmth. Went 1-2 degrees above suggested blends for highs Saturday and Sunday. .LONG TERM...(Monday through Thursday) Issued at 242 PM CDT Fri Aug 14 2020 General pattern of ridging over the western CONUS will lead to general troughiness over the eastern CONUS. This will lead to northwesterly flow bringing drier air into the Tennessee Valley through the first half of next week. This will limit the shower and thunderstorm potential, with mostly dry weather Monday and Tuesday. Both the GFS and ECMWF show a secondary wave developing, bringing a low pressure system down out of Oklahoma into the Mississippi River Delta region midweek. This will lift a warm front north and southerly flow will bring back moisture to the Tennessee Valley maybe as early as Wednesday, but more likely on Thursday. This will lead to increasing shower and thunderstorm chances again later next week. && .AVIATION...(For the 06Z TAFS through 06Z Saturday night) Issued at 1109 PM CDT Fri Aug 14 2020 An area of showers moving SE over Middle TN could impact the KHSV terminal at the start of the TAF. The showers should diminish during the overnight. Tracking of this activity keeps it just east of KMSL. Light winds and moisture remaining could become low clouds and/or fog in the overnight. Have reduced CIG/VIS values for both terminals until 14-16Z, when mixing from daytime heating should bring in VFR conditions. Light and variable winds overnight, should become NW in the 5-7kt range a few hours after sunrise. Winds should increase into 10-20kt range in the afternoon, as a front moves across the area. A few showers and t-storms are possible Sat afternoon, but did not include them this issuance given too much uncertainty. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...NONE. TN...NONE. && $$ NEAR TERM...RSB SHORT TERM...17 LONG TERM...McCoy AVIATION...RSB For more information please visit our website at weather.gov/huntsville.

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