FXUS64 KHUN 021547 CCA AFDHUN Area Forecast Discussion...CORRECTED National Weather Service Huntsville AL 1047 AM CDT Fri May 2 2025 ...New NEAR TERM... .NEAR TERM... (Rest of Today and This Evening) Issued at 1038 AM CDT Fri May 2 2025 Bottom line up front: severe thunderstorms are forecast to mainly bring the potential for damaging wind gusts (60 mph or greater) and hail (an inch or greater) between 1-9PM today. A Severe Thunderstorm Watch has been issued for Lauderdale, Limestone, Colbert, Franklin (AL), and Lawrence counties in northwest Alabama as well as our three Tennessee counties (Lincoln, Franklin, and Moore) until 5PM. An upper level shortwave is shown to swing over the Tennessee Valley later this afternoon through tonight. Guidance indicates a 50-55 knot upper jet this afternoon decreasing to around 35 knots this evening. Additionally, a low level jet around 35 knots looks to be present this afternoon and into this evening as well. At the surface, a low pressure system over the ArkLaTex and cold front will gradually shift east/northeast through tonight. As for thermodynamics, temperatures are forecast to rise into the upper 70s to lower 80s this afternoon with dew points in the 60s. This, in addition to sufficient breaks in clouds, will lead to plentiful surface-based instability (model guidance shows values potentially reaching around 2800-3500 J/kg this afternoon). Bulk shear values range between 30-35 knots, definitely sufficient for thunderstorm and especially severe thunderstorm development. Low level lapse rates are also shown to be between 7.0-7.5 deg C/km this afternoon. Overall, anticipating a cluster of storms to move into the Tennessee Valley and progress over northwest with strong to severe storms over northwest Alabama between 1-3PM, north-central AL between 4-6PM, and over NE AL between 6-9PM. A few, isolated storms are possible later this morning ahead of the main cluster of storms forecast this afternoon/evening that are the reason for the Enhanced Risk (level 3 of 5) of severe weather outlooked by the Storm Prediction Center. This is evident by the ongoing activity to our west and northwest at present (we'll need to keep an eye on outflow boundaries from these). As for hazards, we have highest confidence in damaging wind gusts from storms this afternoon, with medium confidence in hail, and very low confidence in a tornado or two. Make sure to have multiple ways to receive warning information this afternoon and this evening! Furthermore, these storms will be efficient rainfall producers (PWAT values are between the 75th to 90th percentile when looking at BMX sounding climatology). Thus, these storms could produce a quick 1-2 inches of rain leading to flooding of urban and low-lying areas. Turn Around, Don't Drown if you encounter flooded roads! && .SHORT TERM... (Tonight through Sunday night) Issued at 1034 PM CDT Thu May 1 2025 Convection from Friday afternoon will spread southeastward early Friday evening, with a risk for strong-severe winds and large hail likely to continue for the southeastern portion of the CWFA during this timeframe. In the wake of this feature, models suggest that surface pressures will begin to fall across southern AR late tomorrow afternoon, as the northern stream trough digs further southeastward, with a weak surface low expected to form and lift northeastward into western KY by 12Z Saturday as an amplifying wave within the base of the trough shifts across MO with an increasing neutral tilt. Rain and embedded thunderstorms will redevelop across the local area early Saturday morning as this occurs and stronger mid-level height falls begin to spread across the region. Although mid-level flow will begin to back to SW and strengthen to 40-45 knots in advance of the trough to our northwest, the improvement in deep-layer shear will be negated by a convectively-overturned airmass featuring CAPE less than 500 J/kg. Thus, lightning and locally heavy rain will be the main impacts from storms early Saturday morning. Present indications are that the surface low to our north will track very slowly northeastward across central KY and into the Upper OH Valley Saturday, as the mid-level cyclone becomes increasingly cutoff from the polar westerlies and drifts eastward into the Lower OH Valley. Widespread rain and thunderstorms will persist across our region ahead of the trailing surface cold front, which should spread slowly southeastward through our CWFA late Saturday afternoon/early Saturday evening. Although SW flow aloft will continue to gradually strengthen (improving deep-layer shear) throughout the day Saturday, extensive clouds and precipitation ahead of the front will limit diurnal warming and destabilization. That said, if limited breaks in morning clouds and precip do occur, shear will support a limited risk for updraft organization during the afternoon. Precipitation will finally end for the southeastern portion of the forecast area early Saturday evening, with light NW flow at the surface advecting a drier and slightly cooler airmass into the region from Saturday night-Sunday night. Although a few wrap- around showers will be possible Sunday (mainly to our north), we will only include a 10-20% POP at this time. Lows will be in the u40s-l50s, with highs of 65-70F Sunday. && .LONG TERM... (Monday through Thursday) Issued at 1034 PM CDT Thu May 1 2025 Latest extended range guidance suggests that a cutoff upper low in the vicinity of the Lower OH Valley on Monday morning will drift east-northeastward and away from the region by Tuesday, as an amplified ridge translates northeastward ahead of a weaker cutoff low over the southern Rockies. Dry conditions will prevail during this period, with a surface ridge maintaining light/variable winds. Highs will warm back into the mid 70s by Tuesday, with lows remaining in the u40s-l50s. During the period from Tuesday night-Thursday, the unorganized cutoff upper low over the southern Rockies will weaken and spread northeastward into the southern Plains, perhaps including multiple embedded circulations. At the surface, a trough of low pressure will become established from south TX into the Mid-South region, focusing extensive development of rain and thunderstorms to our southwest. It is unclear at this time how much of a lingering influence we will receive from the preceding dry continental airmass, but in general we expect a gradual increase in chances for showers and thunderstorms into the 30-50% range on Wednesday/Thursday (especially across the western portion of the CWFA). && .AVIATION... (12Z TAFS) Issued at 644 AM CDT Fri May 2 2025 A system developing over the eastern Great Plains nearing this region will cause conditions to become inclement as we go into the afternoon and tonight. As of TAF issuance, scattered convection forming over northern MS and adjacent TN should for the most part remain just north of the KMSL terminal early in the TAF. As the system nears, chances for showers/storms will increase from west to east - mainly starting this afternoon into the evening. VSBY/CIG values should be reduced to to MVFR, at times lower in and near stronger/heavier convection. Did not go below MVFR range this issuance given uncertain confidence further into the future. Have kept a VCTS in for the evening, as enough of the guidance indicated this potential into the overnight, as more disturbances move over the region. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...None. TN...None. && $$ NEAR TERM...26 SHORT TERM....70 LONG TERM....70 AVIATION...RSB