Area Forecast Discussion
Issued by NWS Huntsville, AL
Issued by NWS Huntsville, AL
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210 FXUS64 KHUN 251724 AFDHUN Area Forecast Discussion National Weather Service Huntsville AL 1224 PM CDT Sat May 25 2024 ...New AVIATION... .NEAR TERM... (Rest of Today) Issued at 927 AM CDT Sat May 25 2024 The early morning system prompting a severe thunderstorm warning has decreased in intensity and continued east beyond the AL border. In its wake, current satellite and surface obs indicate significant clearing with morning temps already rising into the high 60s to low 70s. Partly cloudy to mostly clear skies will likely develop through the next several hours yielding high temps in the mid to high 80s. The sunny, warm, and moist conditions developing throughout the day will prime out local environment for the potential for additional strong to severe storms this afternoon. The severe threat will be highly conditional as it will be contingent on several small elements and how they evolve throughout the day. Storms will be diurnally driven meaning stronger surface heating throughout the day will create a better environment for storms to live in. The uncertainty remains in exactly when, where, and if, storms will initiate. A likely scenario right now appears that afternoon storms will initiate along lingering outflow boundaries from morning convection. Where those outflow boundaries set up will give us a better idea as to if our CWA will remain mostly clear or see isolated strong to severe storms. Any storms that do initiate or drift into our area will pose a threat for damaging winds, hail, and frequent lightning. Damaging wind will be our primary threat as the afternoon environment looks favorable for downbursts. Fortunately the tornado threat will greatly diminish throughout the afternoon as our shear will steadily decrease throughout the day. Regardless of confidence in threats, make sure to have multiple ways to receive warnings and remain weather aware as even small storms can produce frequent lighting. && .SHORT TERM... (Tonight through Tuesday) Issued at 359 AM CDT Sat May 25 2024 The potential for microbursts will continue into the evening hours before subsiding with the loss of diurnally driven instability around sunset. Overnight, a break in rainfall will take place for most of the TN Valley. However, low chances (around 30% or less) have been kept in due to lingering showers. Sunday into Monday, high sfc pressure off the southern coast of Florida will cause southerly winds to advect moisture from the Gulf to the Tennessee Valley. This will support increased dew points and subsequently an increased heat risk (to be discussed at the end of this short term section) ahead of a cold front. A slight risk (level 2/5) is in place for most of the area (primarily north of the TN River). Timing continues to shift later, however, it is looking like storms will move in from the NW around 1 AM CDT and continue southeastward through noon. These storms will bring risks of damaging winds (medium confidence), heavy rainfall/localized flash flooding (medium confidence), hail (medium confidence), and one or two tornadoes (low confidence). Forecast soundings currently have us capped overnight, however, there is sufficient shear in place as well as low level streamwise vorticity to support a relatively higher tornado risk if that cap is broken. Steep mid level lapse rates (7-8 C/km) and MUCAPE around 1700-1900 J/kg will also support a hail risk. DCAPE around 900-1100 J/kg also exists in these model soundings, accompanied by sufficient shear to warrant a damaging wind risk. We will continue to monitor this system closely. As mentioned previously, high dew points will contribute to an increased, moderate heat risk with high temperatures forecast to reach the low 90s Sunday. During this time, heat will affect individuals most sensitive to heat, especially those without effective cooling and/or adequate hydration. Max heat indices during this period will be around 95-99 degrees F. Overnight Monday into Tuesday, dry weather returns (PoPs 10% or less) as high pressure filters in from the northwest and lows drop into the 60s before rising back into the low to mid 80s during Tuesday afternoon. && .LONG TERM... (Tuesday night through Friday) Issued at 359 AM CDT Sat May 25 2024 Sfc high pressure allows for dry weather to settle over the region through the mid week. Upper level shortwaves will allow a very low chance of showers (10% or less) during this time, however, confidence is low in this occurring. High temperatures during this period are forecast to be in the 80s with overnight lows in the 50s/60s. && .AVIATION... (18Z TAFS) Issued at 1224 PM CDT Sat May 25 2024 There will be two periods of concern that will pose a threat to otherwise VFR conditions. This afternoon there will be a chance for scattered thunderstorm development. With very low confidence on location and timing, TS has been left out of the TAF for now. Tomorrow morning there are some indicators of fog and or low clouds. This is shown in the TAF as the ceilings are lowered significantly however confidence on the development of MVFR conditions is also low at this time and thus it has been left out of the TAF for now. Both TS chances and MVFR chances will be refined in further TAF issuances. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...None. TN...None. && $$ NEAR TERM...RAD SHORT TERM....HC LONG TERM....HC AVIATION...RAD