950 FXUS64 KHUN 230834 AFDHUN Area Forecast Discussion National Weather Service Huntsville AL 334 AM CDT Fri Apr 23 2021 .NEAR TERM...(Today) Issued at 334 AM CDT Fri Apr 23 2021 High pressure will slide off to the east today as a deepening upper- trough approaches the region. Current satellite shows mid to high cloud cover overspreading the region, with ceilings generally running around 10 kft or higher as of 08z. Weak isentropic lift has generated some light returns on radar, and its certainly possible a few sprinkles of rain may be felt early this morning, especially in northwest Alabama. However, do not think this will be widespread enough to warrant a mention and will keep a silent 10 PoP for the daytime period. This cloud cover will serve to limit heating somewhat, but with a stronger southerly fetch of wind advecting in a warm, moist air mass front the south we still should be able to outperform yesterdays highs and have temperatures peaking in the upper 60s to lower 70s by this afternoon. .SHORT TERM...(Tonight through Sunday) Issued at 334 AM CDT Fri Apr 23 2021 The aforementioned upper-trough will quickly swing eastward across the Deep South Friday night into Saturday as surface low develops over the ArkLaTex and shifts into the Mid South region. This will result in a period of widespread showers and isolated to scattered thunderstorms as strong dynamic lift from the upper trough and frontogenetic forcing from a cold front will tap into this moist environment, resulting in multiple rounds of rainfall during this window. After a dry start to the evening, showers will increase substantially by Midnight (from west to east) and overspread the entire area late tonight into early Saturday morning. This shower activity will be locally heavy at times, but given how dry its been of late do not foresee any flooding issues. A couple more rounds of showers and storms are possible during the day on Saturday -- with their intensity tied to much much destabilization can occur. The initial round of moderate to heavy rain should be tapering off by mid Saturday morning, with a second, decaying line of showers/storms moving in by the late morning and early afternoon along another piece of outflow/prefrontal trough. Instability will be fairly meager during this window, so expect this round to remain sub-severe (if it even can hold together at all). Uncertainty lies with a third round of storms during the afternoon and evening. If the environment can recover via heating during the 16-20z window, the potential for some surface based clusters of storms may exist along/ahead of the surface cold front. Think the extended CAMs are way overdoing the recovery/thermodynamics with this and have leaned more on the global models and their ensembles for this part of the forecast. Current thinking is that there will likely be sufficient destabilization (combined with some favorable deep layer shear) to support some scattered, semi-organized convection during the afternoon. However, parameters will be much more favorable for border-line strong to marginally severe activity, than any roubust, severe convection. This will be a conditional threat and dependent on what the environment is like on Saturday, which is still somewhat uncertain at this time. Cold front will sweep through the area Saturday night, with a drier air mass moving in early next week. Morning cloud cover on Sunday should dissipate by the afternoon, allowing for some decent heating and highs in the 70s. .LONG TERM...(Sunday night through Thursday) Issued at 334 AM CDT Fri Apr 23 2021 Upper high pressure ridge will move into the Deep South region early to mid week, resulting in a substantial warm up as we enter a period of deep southerly flow. With a mostly sunny sky and a strong warm air advection regime, expect highs to warm into the low to mid 80s each day. Very late in the period (Wednesday evening/night into Thursday), an intense upper low digging out of the Desert Southwest will shift onto the southern Plains and eventually into the Mid-Mississippi Valley. This will drag a cold front into the Tennessee Valley late Wednesday night into Thursday. Some considerable uncertainty exists between the global models and their ensembles regarding this timing of this system. Latest model trends continue to be slower with this system and for this reason, PoPs have been capped at 40-50 percent, per the NBM for Day 7. Given the favorable dynamics with this system, we'll have to watch for the possibility of strong to severe storms by the middle to end of next week across the Tennessee Valley/Mid South. && .AVIATION...(For the 06Z TAFS through 06Z Friday night) Issued at 1109 PM CDT Thu Apr 22 2021 No changes to previous aviation forecast reasoning, as developing WSW flow ahead of a storm system over the southwestern CONUS will lead to an increase in altostratus clouds thru the early morning hours. Overcast cigs will become established arnd FL080 by 6-7Z, and should remain at this level before lifting/scattering later Friday morning. Sfc winds will shift to lgt ESE overnight, before veering further to SSE and strengthening by 16Z. The leading edge of more widespread rainfall associated with the approaching storm system may begin to impact MSL btwn 24/4-6Z, and -RA has been included in the prevailing weather group during this period. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...NONE. TN...NONE. && $$ NEAR TERM...AMP.24 SHORT TERM...AMP.24 LONG TERM...AMP.24 AVIATION...70/DD For more information please visit our website at weather.gov/huntsville.