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Area Forecast Discussion
Issued by NWS Huntsville, AL
Issued by NWS Huntsville, AL
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943 FXUS64 KHUN 162315 AFDHUN Area Forecast Discussion National Weather Service Huntsville AL 615 PM CDT Fri Aug 16 2024 ...New AVIATION... .NEAR TERM... (Tonight) Issued at 106 PM CDT Fri Aug 16 2024 Active afternoon of weather is on tap for the Tennessee Valley as a cold front approaches the area from the north and west. This feature will serve as a lifting mechanism for showers and thunderstorms later this afternoon and into the early portions of the evening hours. Good heating this morning has warmed temperatures into the low to mid 90s as of 18z and they will continue to climb another 2-4 degrees this afternoon. SBCAPE values of 2500-3500 J/kg have evolved, with no capping inversion. Mid-level dry air and an inverted-v sounding profile would favor an environment favorable wet microbursts or line segments (though bulk and effective shear values remain fairly modest and around 20-30 kts at most). Main timing of this still appears to be 19-01z this evening, with PoPs generally in the medium category (40-60%) through 01-02z. Precipitation chances will wane quickly with the setting sun, but would think that cloud cover may be slower to clear this evening, resulting in a mostly cloudy sky. Some partial clearing may allow for localized patchy fog in areas that see locally heavier downpours. Otherwise, it`ll just be a warm/humid night with lows in the mid 70s. && .SHORT TERM... (Saturday through Monday) Issued at 106 PM CDT Fri Aug 16 2024 We remain in an active pattern as the cold front will be slow to move across the Tennessee Valley and another shortwave rotates around the parent low over the meandering over Great Lakes. Hi-Res guidance continues to highlight the next impulse and associated convection to move through the region mid/late morning into the early afternoon (14-18z). Instability parameters won`t be quite as high given the morning cloud cover, but would anticipate at least 1000-2000 J/kg of SBCAPE to go along with 20-30 kts of bulk shear, allowing for a marginal threat for a few strong to severe storms. Low confidence in an additional round of convection late Saturday afternoon and evening -- all dependent on the timing of the first round and how quickly we can recover. The aforementioned boundary will sag further to the south into central Alabama on Sunday, but with yet another shortwave traversing the area, low to medium chances (20-40%) for afternoon showers and storms seemed warranted once again. A few of these storms could be locally strong to severe during the peak heating of the afternoon. The upper trough will pivot into the central Appalachians and Mid Atlantic on Monday, with northerly flow ushering in a cooler and drier air mass bringing an end to the rain chances and a break from 90s temperatures as highs Monday will only peak in the mid to upper 80s. && .LONG TERM... (Sunday through Thursday) Issued at 357 AM CDT Fri Aug 16 2024 Consensus guidance from the 16/00Z suite of global models suggests that a mid-level longwave trough will become established across eastern North America early in the period, with moderately strong NNW flow aloft predicted to remain in place across the TN Valley through the middle of next week. At the surface, an area of low pressure will shift east-northeastward across southern Quebec and into western New England on Sunday/Sunday night, with the trailing cold front expected to cross the CWFA at some point Sunday afternoon. Thus, a low-medium (20-40%) chance for showers and a few thunderstorms has been maintained in the grids through late Sunday morning. Although some wrap-around stratus clouds may impact the northeastern portion of the region on Sunday night/Monday (in the wake of the departing cyclone), probabilities for any light rain showers or sprinkles remain very low (5-10%). Light-moderate N-NE flow will advect a cooler/drier continental airmass southward early next week, with highs falling into the m-u 80s for most of the region beginning Monday, and lows dropping into the u50s-l60s Tuesday morning (and perhaps m-u 50s Wednesday morning). Present indications are that low- level ESE flow will return Wednesday night as a subtle surface trough retrogrades westward across the region, and this will allow for a minor increase in both low-level moisture and chances for showers on Thursday. && .AVIATION... (00Z TAFS) Issued at 615 PM CDT Fri Aug 16 2024 Lingering clusters of shra/tsra have moved S/E of the two main terminals heading into the evening hrs this Fri. This should translate into VFR conds prevailing into the morning period Sat, with mid/high clouds remaining in place over much of the area. Sct to perhaps num shra/tsra are then possible later in the day Sat, as additional upper disturbances traverse SE over parts of the region. Timing and strength of these additional waves are somewhat uncertain heading more into the day Sat and a PROB30 group has been maintained later in the TAF period. Light SSW winds near 5 MPH will also become more west near 7-8kt Sat morning. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...None. TN...None. && $$ NEAR TERM...AMP SHORT TERM....AMP LONG TERM....70 AVIATION...09