Area Forecast Discussion (AFD)
Issued by Huntsville, AL (HUN)
000 FXUS64 KHUN 200126 AFDHUN Area Forecast Discussion National Weather Service Huntsville AL 726 PM CST Sat Jan 19 2019 .NEAR TERM...(Tonight) Issued at 725 PM CST Sat Jan 19 2019 The cold front is now completely east of the area but winds behind the front have ramped up quickly. RAP analysis shows the pressure gradient across the area tightened quickly and resulted in wind gusts of 35mph to 37mph. These stronger gusts should continue through the rest of the overnight period and we will continue the Wind Advisory. Temperatures are falling a bit quicker than the previous forecast and most model guidance had advertised and have made adjustments to reflect these cooler temps. With continued cloud cover overnight and based on temperatures to our north think that our forecast for lows in the upper 20s is reasonable. May end up having to nudge values down a degree or so but we are on track. The combination of these low temps and the breezy conditions will send Wind Chill values into the teens Sunday morning. The strong winds and drier air rushing into the area will really help to evaporate moisture off of the roads. We can probably expect some patchy black ice where water has pooled but most road/concrete surfaces should be okay. The focus then turns to the potential for any wintry precipitation overnight. Current radar, satellite, and observations indicate a narrow band of snow is occurring on the back side of the strong upper low. This low is currently north of Nashville and moving fairly quickly E/NE away from the area. Because the system will be pulling away from the area we should start to lose some of the lift that is supporting these light snow showers near Memphis, TN. In addition to the loss of lift, drier air working in above this shallow moisture layer may result in a shrinking band of precip as it moves towards northern Alabama and southern middle Tennessee. With that in mind have reduced PoPs a bit overnight but think we'll still end up with some flurries or light snow showers. We do not expect any accumulations for much of the area. The exception to that is in the higher terrain across southern middle TN and far NE AL where a light dusting is possible on grassy and elevated surfaces. We will be monitoring the radar trends closely to see if the current band of light snow in western TN holds on as it moves towards the area. Another update before midnight is possible if that were to occur. .SHORT TERM...(Sunday through Monday) Issued at 325 PM CST Sat Jan 19 2019 With the upper low/trough axis lifting newd into the OH Valley Sun morning, some very limited moisture may result in a few flurries tomorrow morning, but this should only last a couple of hrs. Clouds will then begin to diminish later in the day, as strong high pressure builds into the Midwest/OH Valley states. With lingering NW winds around 10-15 mph coupled with perhaps higher gusts, temps may struggle to get much higher than the lower 30s across srn mid TN and the mid 30s over north AL. Wind chill values only look to climb into the mid/upper 20s for most of the area later in the day Sun. Quiet and cold wx conditions are then xpcted Sun night into Martin Luther King Jr Day, under mostly clr skies. Lows Sun night look to fall well into the lower 20s, with temps then perhaps rebounding into the lower/mid 40s during the day Mon, as the sfc high north of the area begins to translate ewd. .LONG TERM...(Monday night through Friday) Issued at 325 PM CST Sat Jan 19 2019 A moderating trend in the wx/temps is then xpcted to gradually begin Mon night into Tue, as the sfc high moves into the nrn/mid Atlantic states. This should allow low level flow to veer more to the ESE, and allow moisture to begin spreading back into the area. Rain chances also look to return later in the day Tue, as another deep upper trough axis moves into the Plains states. A potent sfc low associated with this next upper trough looks to lift into the Great Lakes, with an attendant cold front stretching swwd into the srn Plains/west Gulf Coast. There remains some spread in the latest global model runs with the handling of this next system, with the 12Z ECMWF still the more progressive solution. In any case, the lead cold front should sweep thru the area during the day Wed, with rainfall then beginning to taper off from the west Wed night. Total rainfall amounts with this next system look to be around 2-2.5 inches. Colder air spreading into the region with this next system following the passage of the front Wed coupled with some lingering moisture may result in a wintry mix or changeover to light snow late Wed night into Thu. Some light accum around a quarter inch or so are possible, but this will be dependent on the influx of drier air into the region as the upper trough moves across the Gulf states and a potential second sfc wave lifts newd away from the area with the passing front. High pressure out of the srn/mid Plains will then build into the region late in the work week, with quiet and seasonably cool conditions xpcted Thu/Fri. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 520 PM CST Sat Jan 19 2019 The cold front has pushed through both terminals with winds shifting to the W/NW. Expect wind gusts between 25 to 30 kts overnight. Winds begin to diminish after 12z Sunday with gusts dropping below 20kts. Cigs have lowered in the wake of the front with bases down to 1,000 to 1,500ft. Brief lowerings to 800ft are possible through 02z. There is still some uncertainty but a brief change over to a rain/snow mix is possible after midnight. No accumulations are expected. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...Wind Advisory until 7 AM CST Sunday for ALZ001>010-016. TN...Wind Advisory until 7 AM CST Sunday for TNZ076-096-097. && $$ NEAR TERM...Stumpf SHORT TERM...09 LONG TERM...09 AVIATION...Stumpf For more information please visit our website at weather.gov/huntsville.