501 FXUS64 KHUN 110718 AFDHUN Area Forecast Discussion National Weather Service Huntsville AL 218 AM CDT Thu Oct 11 2018 .NEAR TERM...(Today) Issued at 218 AM CDT Thu Oct 11 2018 A deformation band of heavy rain associated with TC Michael was nearly stationary over NW GA into eastern TN. Although close to the AL border, it will remain just east early this morning. Lighter narrow shower bands over north AL and middle TN will continue early this morning, mainly east of I-65. Water vapor imagery shows a sharp boundary between mid-high level moisture associated with Michael near and east of I-65 while a trough axis and dry mid-upper level air to the west. RGB imagery shows clearing entering middle TN and far northwest AL behind the cold front which is somewhat masked by the pressure field influenced by Michael. The short range models bring the trough axis, front and clearing east through the area early this morning, with upper level ridging following quickly behind by midday into the afternoon. With daytime mixing, gusty north-northeast winds are expected to develop this morning, with gusts above 20kt, especially in the higher terrain of our eastern counties. Temperatures and especially dew points will be much lower today, so it will feel much more Fall-like today. .SHORT TERM...(Tonight through Saturday) Issued at 218 AM CDT Thu Oct 11 2018 A more or less zonal 5h flow pattern will develop over the southern U.S. while a vigorous shortwave drops southeast through the upper Midwest on Friday, and through the OH valley Friday night into Saturday. Another cold front will drop southeast bringing light showers just to our north and northwest Friday night into Saturday. However, strong subsidence behind the shortwave will likely dry the atmosphere sufficiently eroding clouds and rain chances this far southeast. The 5h pattern rapidly becomes zonal again by afternoon. After chilly lows in the m40s-a50 Saturday morning, afternoon highs will only reach the m60s atop the Cumberland Plateau with l70s in valley locations. .LONG TERM...(Saturday night through Wednesday) Issued at 218 AM CDT Thu Oct 11 2018 The brisk zonal 5h flow across the southern U.S. will result in rapid progression of minor shortwaves that eject from the cutoff low that develops over So Cal. This results in moderate overrunning/isentropic ascent across the mid South Saturday night into Sunday. Elevated instability, LLJ of 40-50kt at 850 mb and resulting moisture transport will likely help to form one or more MCS clusters across AR moving into western TN and north MS. Instability and drier air to the east and the best convergence located just northwest of our forecast area brings some uncertainty to how far southeast precipitation will occur. Will go with likely PoPs north and northwest to lower chance southeast from Sunday into Sunday night. On Monday, a shallow cold air mass will drop southeast into the area. With the low level jet weakening, and lack of upper QG forcing, PoPs will go down Monday into Monday night. The shallow nature of the cold air and it's progression will certainly make temperature forecasting difficult for highs Monday. For now, will side above the suggested blend with midday max temps likely to occur. Will go with lower 70s north and west areas with u70s to near 80 likely further southeast before the front arrives. In fact, raw EC and GFS values indicate l80s in our central and southeast areas, so future updates may be needed depending on the speed of the shallow cold layer moving in. Will carry just a slight chance of light showers through Tue morning before drying the forecast out. Lows Tuesday and Wednesday morning will be back down into the 40s to a50 as high pressure at the surface shifts east from the Plains into the OH/TN valleys. Afternoon highs will only recover into the 60s. && .AVIATION...(For the 06Z TAFS through 06Z Thursday night) Issued at 1131 PM CDT Wed Oct 10 2018 Showers have moved east of KMSL and some 4000 foot cigs are still in place. However, this should quickly push quickly east and by 08Z become scattered in nature. Left VCSH in at predominantly between 06Z and 09Z with a tempo for -SHRA during that time. at KHSV. Some MVFR vsbys or cigs are possible with any -SHRA activity. As a front moves east tonight, winds should pick up behind it ~ 08Z at KMSL and 09Z at KHSV. Expect a return to VFR conditions at KHSV by 09Z. Otherwise, winds should remain gusty from the northwest up to 18 knots until sunset on Thursday. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...NONE. TN...NONE. && $$ NEAR TERM...17 SHORT TERM...17 LONG TERM...17 AVIATION...KTW For more information please visit our website at weather.gov/huntsville.