244 FXUS64 KHUN 251745 AFDHUN Area Forecast Discussion National Weather Service Huntsville AL 1145 AM CST Tue Feb 25 2020 .UPDATE... For 18Z TAFS. && .NEAR TERM...(Rest of Today) Issued at 1002 AM CST Tue Feb 25 2020 Most of the central Tennessee Valley started off with generally clear skies. An exception was our more southeastern areas (Cullman, Marshall, DeKalb counties) under the northern edge of a +115kt subtropical jet moving from a source region southwest of the Baja. Other clouds also were noted over parts of far NE Alabama and adjacent southern middle Tennessee. A brief period of sun to start the day unfortunately will be short lived, as more lower clouds move in from the west. This stratus, with bases above 3kft AGL were over spreading much of NW AL. But from upstream observations, expect cloud bases/ceilings to be reduced below 3kft for the late morning and afternoon for much of the forecast. Despite the increase in clouds, a steady SW-W flow will help boost high temperatures close to seasonable norms (which are around 59 degrees for much of the Valley). Given more clouds to the west, cooler highs in the mid and upper 50s are expected, with lower 60s over the more sunny eastern areas. Unlike yesterday, dry weather will also continue today. An area of low pressure that in part brought rain to the Valley yesterday, should continue moving eastward, reaching the Mid Atlantic this evening. The low moving to the east will induce a more westerly, then NW flow in the late afternoon and evening - ahead of another system set to impact the region later tonight and on Wednesday. .SHORT TERM...(Tonight through Thursday night) Issued at 346 AM CST Tue Feb 25 2020 An upper level trough will deepen and amplify and it lifts into the Midwest tonight. As southwesterly flow aloft increases ahead of the system, we will see an increase in cloud cover, moisture and overnight lows only falling into the lower 40s. As the previously mentioned sfc low lifts through the OH Valley, it will pull an arctic front into the Lower MS Valley and develop a few showers out ahead and along it. Isolated to scattered showers will spread west to east overnight and into Wednesday with light QPF amounts. CAA and breezy northwesterly sfc winds of 10-15kts and gusts of 20-25kts will make sure we feel the colder air arrive behind the front. Daytime highs will only reach the upper 40s to lower 50s. Drier air behind the front will bring precip to an end from west to east during the afternoon to evening. A little bit of snow is possible in our higher elevations in Southern Middle TN and NE AL Wednesday night into Thursday morning if cold air beats the drier air. Model soundings are cold enough with temps in the upper 20s, but show the race against time with enough moisture being in place for it to happen. If it does occur, little to no accumulation and minimal impacts are expected. Winds remain elevated overnight which will provide a wind chill in the teen to lower 20s by Thursday morning, so be sure to bring pets inside and bundle up before heading out to the bus stop or out the door for the morning commute. Cloud cover will slowly decrease through the day on Thursday, but don't let the sunshine fool you, cooler conditions will be in place. Temps will be below normal with daytime highs in the lower 40s with overnight lows around 30 degrees. .LONG TERM...(Friday through Monday) Issued at 346 AM CST Tue Feb 25 2020 Models have been a bit wonky during the Friday-Saturday time frame, just now with the 00Z runs changing to bringing more precip with the first clipper Friday, and little-to-nothing with the now much weaker shortwave on Saturday. First, I'd like to state that the National Blend of Models tool that we use essentially blends a large grouping of models and gives the percentage chance of precipitation based on all these different models. The final result is only around a 20-30 percent chance of precipitation on Friday night into Saturday morning, so nothing is guaranteed as of right now. However, if precipitation does occur, here's how it may play out based on the current blend of models. Precipitation would start out as all rain Friday evening, as temperatures will be several degrees too warm for snow. However, this will change as the night progresses and temperatures start to fall. Around 10 PM to midnight appears to be the time when we really start to see temperatures get cold enough for snow to start to mix in. As temperatures continue to slowly drop overnight to the eventual lows around 28-32 degrees, expect we will see a transition to all snow overnight. QPF appears to be fairly light through this event, so if we do get snow, amounts should be light and accumulations should be minimal. We will still have a fairly dry layer in place through the lower-levels which will also hinder much precipitation from even making it to the ground without evaporating. Then, snow will also be fighting ground and low-level temperatures, which won't reach below freezing until closer to sunrise. The mostly likely places to see any snow actually accumulate will probably be in higher elevations and more rural areas across NE Alabama and south Middle Tennessee. A lot can change with this forecast, so keep an eye on this time frame if you have any travel plans. Saturday, any snow will change back over to rain as temperatures start to rise back up during the day. Precip chances finally come to an end Saturday evening as the shortwave as well as the broad upper- level trough finally eject off to the east. An upper-level ridge will be building over the Southeast on Sunday, and with the aid of strong WAA out ahead of a developing strong low pressure system over the southern Great Plains, temperatures will climb rapidly going into early next week. On Monday, as the low pressure system starts to develop into a mature cyclone, we see the warm front lift northward through the Tennessee Valley, bringing more widespread rain. && .AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon) Issued at 1145 AM CST Tue Feb 25 2020 An area of mostly MVFR (1-3kft AGL) stratus was overspreading much of the area from the west. This was partially in response to the formation of a storm system between the Ozarks and Ohio Valley. A WNW flow rounding this system should keep the stratus in place for areas near and north of the Tennessee River into the evening. The late morning high resolution visible satellite view indicated some erosion on the SE side of the encroaching stratus. More cold air filtering in should result in the stratus resuming greater coverage over the area tonight. Rain associated with this system should begin affecting the terminals in the overnight; starting at KMSL around 26/0800Z and KHSV at 1000Z. Stayed optimistic with CIGs, reducing them into the low MVFR range (near 1kft AGL). More cold rain and deeper moisture could bring IFR CIGs late in the TAF. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...NONE. TN...NONE. && $$ NEAR TERM...RSB SHORT TERM...JMS LONG TERM...McCoy AVIATION...RSB For more information please visit our website at weather.gov/huntsville.