Area Forecast Discussion
Issued by NWS Huntsville, AL
Issued by NWS Huntsville, AL
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871 FXUS64 KHUN 050648 AFDHUN Area Forecast Discussion National Weather Service Huntsville AL 1248 AM CST Wed Feb 5 2025 ...New AVIATION... .NEAR TERM... (Tonight) Issued at 904 PM CST Tue Feb 4 2025 A dense mid level stratus deck will continue to expand east across the area tonight with overcast conditions expected area wide by the morning. This cloud cover will help keep temperatures well above normal tonight, with lows only dropping into the low to mid 50s. Reduced visibilities could become an issue overnight given the amount of low level moisture, but a Dense Fog Advisory is not planned at this time. Low rain chances (20-30%) will move from west to east during the early morning hours, but most locations should remain dry tonight. Only minor changes were made to cloud cover during the evening update, but otherwise the previous forecast remains on track. && .SHORT TERM... (Wednesday through Thursday night) Issued at 157 PM CST Tue Feb 4 2025 An amplifying shortwave will shift from the southern Plains into the Mid-Mississippi/lower Ohio Valley Wednesday into Wednesday night, forcing the aforementioned boundary to creep back northward into the Tennessee Valley as a warm front. Additionally, deep layer forcing from the deepening shortwave and the northward advancing front should lead to more widespread development of convection from the mid/late morning hours through the afternoon and early evening. An initial glance at model soundings indicates some meager CAPE values aloft which will allow for some elevated convection through the early afternoon. With limited surface heating and relatively poor lapse rates, it is uncertain exactly what the thermodynamic profile will be by the afternoon hours on Wednesday across the region. However, deep southerly flow aloft will aid in moisture transport and the advection of a warmer air mass -- with highs in the upper 60s to lower 70s being common once again. Probabilistic guidance is hinting at medium to high chances of at least a couple hundred J/kg of SBCAPE -- mainly along/west of I-65 by the mid/late afternoon and early evening. With convection continuing to develop with the advancing warm front, and a 35-40 kt LLJ pushing northward enhancing the bulk shear values, think some organized clusters of storms may be in the cards during this late day/peak heating timeframe. If this surface-based instability is realized, a few storms may be locally strong to perhaps marginally severe with gusty/damaging winds being the main concern. By the early evening, precipitation should be tapering off as the front lifts northward toward the TN/KY border area and despite the boundary layer remaining surface- based, convection (and the primary severe threat) will remain displaced further to the north along/north of I-40. Deep southerly flow will reinforce this warm/moist air mass on Thursday, and with a few breaks in the clouds temperatures will be able to climb into the low to mid 70s by the afternoon. The aforementioned boundary to the north will then drop back to south as a weak cold front late Thursday afternoon/evening into Thursday night, bringing high chances (70-90%) for showers/storms. With very limited instability Thursday night, feel like most of the convection will be elevated in nature and threat for anything strong will be low. && .LONG TERM... (Friday through Monday) Issued at 432 AM CST Tue Feb 4 2025 The extended portion of the forecast period will begin on Friday, with a stalled front likely to bisect the local area in an E-to-W fashion. Latest extended range model data suggests that the boundary will retreat northward on Friday afternoon/evening, as the eastward motion of a broader longwave upper trough (across the northwestern CONUS) initiates development of another lee cyclone across eastern CO. Present indications are that the forecast area will be entrenched within the warm sector of this cyclone on Saturday, with low clouds and some light showers possible at times. However, higher probabilities for additional showers (and perhaps a few thunderstorms) will come from late Saturday night- early Sunday morning as the surface low ejects northeastward into IN/OH, sending a stronger cold front southeastward into the TN Valley. Given the orientation/location of the broader longwave trough on Sunday, lift above the shallow postfrontal inversion will support widespread/cold anafrontal rainfall late Sunday morning, which should gradually dissipate from NW-to-SE Sunday afternoon as the depth of the cool/dry airmass increases. Lows on Monday morning will fall back into the mid 30s, with a moderately strong north wind providing wind chills in the u20s-l30s. Chances for rain may begin to increase once again by Monday afternoon as yet another area of low pressure forms over the southern High Plains, but this is highly uncertain at this time range. && .AVIATION... (06Z TAFS) Issued at 1248 AM CST Wed Feb 5 2025 VFR conditions exist at the HSV/MSL terminals at the present time, featuring calm winds and broken layers of stratus btwn 3.5-6 kft AGL. As a warm front begins to lift northward thru the region later this morning, lgt SHRA will become more prevalent and both cigs and vsby should fall into the MVFR range. Occasional periods of IFR conditions will be possible during the day as clusters of warm sector SHRA/TSRA spread northeastward across the region, and AWWs may be required for lightning. Afternoon precipitation will spread northeastward and out of the region this evening, with SSW flow expected to gradually strengthen thru 6Z Thursday. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...None. TN...None. && $$ NEAR TERM...25 SHORT TERM...AMP LONG TERM...AMP AVIATION...70/DD