Area Forecast Discussion (AFD)
Issued by Huntsville, AL (HUN)
000 FXUS64 KHUN 142330 AFDHUN Area Forecast Discussion National Weather Service Huntsville AL 530 PM CST Wed Nov 14 2018 .UPDATE... For 00Z TAFS. && .NEAR TERM...(Tonight) Issued at 315 PM CST Wed Nov 14 2018 An early winter wx event is occurring mainly to our west across northern MS and western TN. An upper level system remains parked over central AR but should begin to shift NE overnight tonight. A surface low was moving across central AL E/NE into NE AL and southern middle TN. What looks to be unfolding is a strong low/mid jet is advecting warmer temps (+3C) into northern AL and central TN. This WAA has kept much of the precip in liquid form across our area and latest radar CC data would suggest this should stay that way. However, just over the state line in MS and TN we are seeing stronger CAA near the surface and this has resulted in some of the liquid precip refreezing into sleet. The thinking for the rest of the evening is that as the upper level system starts to shift NE this almost trowal that exists just to the west will pivot N/NE. Drier air shown in latest water vapor imagery will advect in behind this feature and can be seen in latest radar imagery. Where you have a sharp gradient between light to moderate precip along the state line and little to no precip west of that. Even though we may start to see radar returns diminish think we will still have enough forcing/lift to support some light drizzle/rain tonight into tomorrow morning. Have held onto PoPs a little longer out west and as the cooler/drier air starts to spread into the area we could see a change over to a mix of freezing drizzle/rain. Maybe even some snow grains mixed in as well. But believe that surface temperatures will be warm enough that we are not expecting any accumulations on road surfaces. We could see some light accums of ice on powerlines and trees overnight but it shouldn't amount to much. .SHORT TERM...(Thursday through Friday) Issued at 315 PM CST Wed Nov 14 2018 Early Thursday morning we may still have enough moisture near the surface and lift for some rain/drizzle. But, models have been a little quicker in ending precip across the area and we will let the next shift see if they need to pull back on precip end times. With temps at freezing to slightly below anything that is falling could freeze. However, as mentioned in the near term section believe that road temperatures should stay on the warmer side and prevent any accumulations on road surfaces. Also, any lingering moisture on the ground should undergo some evaporation as the drier moves in overnight, so that should limit any possible situation where moisture on the surfaces freeze. Forecast soundings show some weakening of an inversion just above the surface but we will still remain overcast for much of the day. This should keep temps in the mid to upper 30s for highs, well below our normal highs 65 degrees. It probably won't be until Friday morning before we are able to see the clouds break out and the sun start to shine. Sunny skies on Friday will allow temps to rebound into the mid 50s. Lows Friday night into Saturday will be in the upper 20s. .LONG TERM...(Friday night through Tuesday) Issued at 315 PM CST Wed Nov 14 2018 Friday night into Saturday, the 5h flow pattern temporarily becomes more zonal across the southern CONUS, with 8h and surface highs building over the southeast. Although low level temperature advection will be more or less neutral Saturday, highs should still reach u50s-l60s. On Sunday, 8h temperature advection becomes slightly cold as flow becomes west-northwest. However, the next trough axis over dropping rapidly southeast from the Rockies into the mid South Sunday afternoon will bring limited mid and high level moisture. The associated weak cold front has only limited rainfall potential. Will keep a Slight Chance going Sunday night into early Monday morning. Yet another shortwave trough drops Southeast through the central corn belt and lower OH valley on Tuesday, arriving in the central and eastern TN valley Tuesday evening. Again, this will be a moisture starved system, with limited precip potential for north AL and south TN. There may be some upslope along the cold front along the northern Cumberland Plateau and Smoky Mtns to our northeast, but will keep a dry forecast here. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 530 PM CST Wed Nov 14 2018 Restricted flying conds continue at both main airports this Wed evening, as a weak sfc wave continues to lift nwd across the cntrl TN Valley. Lower cigs near/just below 1K ft remain in place across the area, and these conds should persist into Thu morning. Light precip also continues to spread newd across the area, with most of this being -ra in nature. However, a brief mixture of -plra is possible near the KMSL airport over the next hr, as cooler air begins to spread ewd into the region. The light precip should taper off to the NE later tonight, with cigs perhaps lifting closer to 2K ft late Thu morning. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...NONE. TN...NONE. && $$ NEAR TERM...Stumpf SHORT TERM...Stumpf LONG TERM...17 AVIATION...09 For more information please visit our website at weather.gov/huntsville.