Area Forecast Discussion (AFD)
Issued by Huntsville, AL (HUN)
314 FXUS64 KHUN 102308 AAA AFDHUN Area Forecast Discussion...UPDATED National Weather Service Huntsville AL 608 PM CDT Thu Aug 10 2017 .UPDATE... For 00Z TAFS. && .NEAR TERM...(Tonight) Issued at 228 PM CDT Thu Aug 10 2017 A couple features and concerns will linger through tonight given the continued progressive pattern. Heavy rainfall, which caused widespread flooding across portion of northern and southeastern Madison County, have primed the saturated grounds for potentially more flooding if rainfall from today's activity again trains over impacted areas. Flooded areas from early this morning will only need around 0.25" or less from a shower/storm to cause more flooding problems. At the moment, scattered showers are being observed, mainly south of the TN River from Colbert Co. through southern Marshall Co. With both 12z soundings from OHX and BMX showing favorable instability, expect shower and thunderstorm coverage to increase through the afternoon. However, with the BMX profile similar to yesterday (same with model profiles), not expecting enhanced coverage of thunderstorms so only mentioned a slight chance for this afternoon/tonight. Rain chances will again favor the southern and eastern zones through this evening with a better shot of seeing a thunderstorm east of I-65 and south of HWY 72. Regardless, any scattered shower/storm could potentially have rain rates exceeding 1"/hr. We're also watching the progression of an complex of thunderstorms moving out of central MS. Hi-res guidance from HRRR, NMM, and ARW show a few showers/storms moving through portions of the TN Valley overnight tonight. As such, have kept chance PoPs in the forecast through the night. .SHORT TERM...(Friday through Saturday) Issued at 228 PM CDT Thu Aug 10 2017 While the pattern will remain fairly active and progressive, we will get somewhat of a transition beginning tomorrow as the warm front shifts out of the area ahead of an approaching cold front swinging into the Mid MS Valley. Ahead of this frontal system, a couple short waves will continue to migrate around the southern fringe of the mid level trough tomorrow. With the added addition of some shear, this extra support will give us a better shot of seeing a stronger thunderstorm or two tomorrow afternoon. While not expecting widespread strong or severe storms, cannot rule out a few storms producing gusts to 40-50mph with small hail. Additionally, any extra rainfall with stress areas with previous flood impacts. By Saturday, we'll still be watching the progression of the cold front moving through the Ohio Valley. Current forecast slows, maybe stalls, the front north of the CWA. With this scenario, we'll continue to see much of the same with humid conditions and daily scattered shower/thunderstorm chances. With the lingering cloud cover and enhanced rain chances, expect temps to continue to run a few degrees below normal during the afternoon and range from the upper 60s to low 70s overnight. .LONG TERM...(Sunday through Wednesday) Issued at 228 PM CDT Thu Aug 10 2017 Majority of the extended forecast sounds like a broken record at this rate and can probably be summed up in one sentence! A series of disturbances will track through the base of a broad upper-level trough and into the TN Valley through early next week. A sfc front will stall to just to our north on Sunday and southerly flow will bring additional moisture in. With PWATs hovering around 2 inches and multiple rounds of showers and thunderstorms on top of soils receiving rainfall from the short term, will need to keep an eye on additional flooding potential. On Monday, an upper-level trough digs out of the Northern Plains and a sfc front departing for the east coast will send a cold front into the TN Valley on Tuesday. Will finally see a decrease in POP values on Tuesday and Wednesday behind the front as some drier air filters in and sfc high pressure tries to build southward into the region. As for temps, daytime highs for the forecast period will continue to be a little below normal reaching the mid/upper 80s. Overnight lows will be near normal, around 70 degrees. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 615 PM CDT Thu Aug 10 2017 Scattered heavy showers and a few thunderstorms will persist this evening into the overnight hours, especially for areas near and east of the KHSV vicinity. At this time, have kept the forecast VFR through 10Z, but if showers or thunderstorms affect the terminal, conditions could easily deteriorate to IFR due to low visibility in heavy rainfall. Mist and possibly fog are expected to develop by 10Z along with at least scattered clouds less than 010agl. It is conceivable that ceilings could also develop and will assess that further this evening. On Friday, more showers and thunderstorms should develop by midday into the afternoon, and have included VCTS at KHSV where the probability is a bit higher than KMSL. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...NONE. TN...NONE. && $$ NEAR TERM...Barron SHORT TERM...Barron LONG TERM...JMS AVIATION...17 For more information please visit our website at weather.gov/huntsville.