312 FXUS64 KHUN 020353 AFDHUN Area Forecast Discussion National Weather Service Huntsville AL 953 PM CST Tue Feb 1 2022 .NEAR TERM...(Rest of tonight) Issued at 953 PM CST Tue Feb 1 2022 Southwesterly flow aloft across the TN Valley will continue to strengthen overnight, downstream from an amplifying mid-level trough shifting east-southeastward across the Rockies. Although a weak disturbance in the southern stream is predicted to lift northeastward over the region during the early morning hours on Wednesday, it appears as if its contribution to synoptic scale ascent will be negligible, with the evolving precipitation regime more closely tied to an increase in southerly flow and moisture advection in the 850-700 mb layer. Boundary layer dewpoints will continue to gradually rise from W-to-E through the early morning hours as precipitation production aloft increases, with chances for measurable surface precipitation expanding most notably in the 9-12Z timeframe. Aside from minor adjustments to POP/weather grids, we have increased winds based on latest guidance, with sustained speeds around 15 MPH and gusts to 20-25 MPH anticipated in lower elevations for much of the 6-12Z timeframe (both sustained winds and gusts will be higher in elevated terrain). Lows will likely range from the mid 40s in the east to the lower 50s in the west, as some evaporative cooling will occur as precipitation begins to reach the surface. .SHORT TERM...(Wednesday through Thursday) Issued at 238 PM CST Tue Feb 1 2022 The upper level trough currently across the Lower Mississippi River Valley will move into the Tennessee Valley early Wednesday. This system will bring in a surge of moisture to the area. Latest models show better low-level convergence and moisture than at this time yesterday. All the models are in fairly good agreement with widespread showers throughout the day. It may not rain all day with some breaks at times, but everyone should see rain tomorrow with amounts ranging from 0.25-0.75 inches. Not expecting to see any flooding on Wednesday but this widespread rainfall will act to saturate the ground. Highs on Wednesday will continue to be mild with persistent warm air advection. Highs will climb into the mid to upper 50s for most locations. The northern stream trough will race eastward on Wednesday and Wednesday night with the arctic front racing across the Great Lakes. Closer to home, upper level flow will be from the southwest with a positively tilted trough located across the Desert Southwest and an upper ridge along the Atlantic Seaboard. The arctic front will become parallel to the upper level flow Wednesday and into Wednesday night and will slow as it sluggishly moves southeastward across the Mid- Mississippi River Valley and Southern Plains. Widespread showers will continue across the forecast area Wednesday night as the front does begin to nudge into northwestern portions of the forecast area early Thursday morning. The front will take most of the day Thursday into Thursday night before clearing the area. Models depict several weak shortwave troughs rotating through the area on Thursday. A strong 300 mb jet develops on Thursday with a broad area of 140-160 kt winds stretching from the Southern Plains into the Great Lakes. This puts the forecast area in the favored right entrance region for divergence aloft. Models also indicate PW values surging into the 1.5-1.7 inch range late Thursday. These values are astronomically high for early February, therefore, expect widespread heavy rainfall late Thursday. Model soundings also indicate some weak elevated instability and there could be a few embedded thunderstorms. Overall storm total rainfall amounts will be around 2.5-3.5 inches with locally higher amounts. This rainfall will lead to rises on area rivers, creeks, and streams and localized flash flooding, especially in areas of poor drainage. .LONG TERM...(Friday through Monday) Issued at 238 PM CST Tue Feb 1 2022 The shallow arctic airmass will move into the forecast area early Friday morning. There could be a brief period of freezing rain on the back edge of the precipitation early Friday morning. Do not expect there would be any snow with 850 mb temperatures well above freezing. For now, believe that the precipitation will exit to the east before temperatures become cold enough for freezing rain. Shallow cold air advection and cloudy skies will keep high temperatures down in the upper 30s to low 40s on Friday. These high temperatures may be a little too warm based on the latest guidance. The arctic airmass is rather short-lived across the area as another upper level low approaches from the west over the weekend. Low-level flow quickly shifts around to the east and then southeast by Saturday afternoon. The GFS shows an inverted surface trough that leads to a few showers late Saturday into Sunday. There are some signals for this in the ECMWF but the precipitation is much further to the south and east. For now, have continued with some slight chances for precipitation late Saturday into early Sunday with drier and seasonal temperatures forecast for Monday. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 657 PM CST Tue Feb 1 2022 VFR conditions will continue at the terminals this evening and thru the early morning hours on Wednesday, with an increasing coverage of As/Cs anticipated ahead of a developing storm system to our west. Although echoes currently seen in radar imagery will initially occur as virga, we have introduced VCSH by 05Z/MSL and 08Z/HSV to indicate increasing probs for lgt showers prior to sunrise. A broader axis of heavier showers will begin to shift slowly eastward approximately 3 hours after the initial onset of light precipitation, with SHRA and MVFR cig/vsby reductions noted by 08Z/MSL and 11Z/HSV. Current indications are that this axis will shift gradually southeastward and away from the terminals by the end of the TAF period. Southeasterly flow will strengthen overnight, with sustained speeds arnd 14 knots (gusts to 22 knots) expected until the pressure gradient begins to relax late tomorrow morning. Regardless, an intense low-level jet will result in LLWS during the period from 03Z thru 13-16Z. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...NONE. TN...NONE. && $$ NEAR TERM...70/DD SHORT TERM...MA LONG TERM...MA AVIATION...70/DD For more information please visit our website at weather.gov/huntsville.