Area Forecast Discussion
Issued by NWS Huntsville, AL
Issued by NWS Huntsville, AL
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599 FXUS64 KHUN 081954 AFDHUN Area Forecast Discussion National Weather Service Huntsville AL 254 PM CDT Wed May 8 2024 ...New NEAR TERM, SHORT TERM... .NEAR TERM... (Tonight) Issued at 254 PM CDT Wed May 8 2024 A dynamic and complex weather event is unfolding across portions of the mid MS and lower OH River Valleys, and will continue to track south closer to the Tennessee Valley this evening. A deepening low over the central US will continue to drive strong southwesterly flow aloft and increasing low level flow will enhance WAA closer to the sfc. A warm and very unstable airmass exists ahead of a cold front, and any thunderstorms that are able to form in this environment will be primed for quick intensification and capable of producing all severe hazards. We believe the initial threat for strong to severe storms will come from supercells progged to develop to our west over western TN and MS. The evolution of these storms has been fairly inconsistent within high-res guidance, with early afternoon trends favoring an initially discrete storm mode at initiation and then congealing into a broken line or line of thunderstorms with embedded supercells. These storms will have the ability to produce large hail and damaging winds due to the favorable combination of instability and shear. A tornado threat will also exist, especially with more isolated supercells that can tap into the stronger low-level helicity. The primary timing for this round will be between 7pm and 2am. This round will be followed by a more organized line of storms later tonight - knocking on the door of NW AL around 2-3am - through the early morning hours. Damaging winds and large hail will be the primary concerns from any storms that form this evening and tonight, but tornadoes and localized flooding are also possible. This remains a low confidence forecast and is largely dependent on the evolution of the mesoscale environment and the amount of thermodynamic support available overnight. Lastly, a flooding threat will linger into the morning hours as storm total rainfall amounts of 1-2" are expected area-wide, with localized amounts up to 3-5" possible. The highest chances for flooding will be in southern middle TN and areas north of the TN River. Confidence in seeing severe weather in the Tennessee Valley tonight is medium to high, while confidence in which round will be the more severe is lower. The degree of instability available overnight will be a critical factor and will be largely dependent on airmass recovery between rounds of thunderstorms. Please check back frequently for updates and have multiple ways to receive warnings that are capable of waking you up. With this being an overnight event, the threat to life and property will be heightened. && .SHORT TERM... (Thursday through Saturday) Issued at 254 PM CDT Wed May 8 2024 Showers and storms will gradually come to an end from north to south Thursday morning, and the severe threat should diminish by 10am at the latest. High pressure will begin to filter into the region Thursday into the weekend, resulting in dry and cooler conditions. A weak shortwave will track across central MS into central AL Thursday night into Friday morning and could result in a few showers/storms mainly south of the TN River, but confidence in this remains low. Highs will be limited to the 70s Friday afternoon with clearing skies and breezy northwesterly winds. && .LONG TERM... (Saturday through Tuesday) Issued at 437 AM CDT Wed May 8 2024 A generally dry weather pattern will continue across the region this weekend. However, a clipper system diving southeastward into the western Great Lakes will send a reinforcing cold front through the region on Saturday, perhaps bringing a few light showers to locations north of the TN River. Chances for rain will begin to slowly return to the region as early as Monday, which is when a series of lower-latitude troughs may initiate the development of one or more areas of low pressure across the western Gulf of Mexico that would shift northeastward early next week. Due to indications of a modifying low-level airmass across the TN Valley, instability will gradually increase as we move forward to Tuesday, with a low chance for thunderstorms apparent as well. && .AVIATION... (18Z TAFS) Issued at 1228 PM CDT Wed May 8 2024 VFR to MVFR cigs have prevailed across the region this morning and are forecast to persist through the majority of the TAF period. Chances for showers and thunderstorms will increase later this evening in the 00-01z timeframe, some of which could be severe. The risk for storms will persist through the morning hours, and reductions to IFR/LIFR conditions will be possible within heavier storms. Frequent lightning, wind gusts up to 50-60kts, and large hail will be the main concerns overnight. Gradient winds sustained at 12-15kts with gusts up to 25kts will also be possible outside of any thunderstorm activity. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...None. TN...None. && $$ NEAR TERM...25 SHORT TERM....25 LONG TERM....70 AVIATION...25