Area Forecast Discussion (AFD)
Issued by Huntsville, AL (HUN)
000 FXUS64 KHUN 172359 AFDHUN Area Forecast Discussion National Weather Service Huntsville AL 659 PM CDT Mon Sep 17 2018 .UPDATE... For 00Z TAFS. && .NEAR TERM...(Tonight) Issued at 343 PM CDT Mon Sep 17 2018 Wrap around moisture from former Tropical Depression Florence continued to bring clouds and isolated showers across parts of the Tennessee Valley. The center of Florence's circulation was situated over SW Pennsylvania, with it heading to the northeast. Showers around this system as they moved over nearby southern middle Tennessee and far northern Alabama were for the most part short lived. Otherwise, another very warm to hot late day continued across the region, as summer refuses to give up. High temperatures so far ranged in the mid 80s, with lower 90s in parts of NW Alabama, where solar insolation was less filtered by clouds. The showers should taper off from SW-NE during the course of the early evening, as the local atmosphere becomes more stable due to a loss of daytime heating and a further departure of the tropical system. With a moist atmosphere in place, night time low temperatures will only cool into the upper 60s. The residual moisture, light winds and near saturated relative humidity values will lead to patchy fog formation during the overnight. The fog should be more prevalent within and near sheltered valley locations and near large bodies of water. Left fog as just patchy - but cannot rule out areas or higher coverage if development is more than expected. .SHORT TERM...(Tuesday through Wednesday) Issued at 343 PM CDT Mon Sep 17 2018 With the departure of the tropical system, dry and very warm to hot conditions continue through the midweek. With more sun than clouds, even with a light northerly flow, high temperatures both days should rise into the upper 80s to lower 90s. Have inched temperatures to the mid 90s for Wednesday, as upper ridging builds over the region from the southwest. More unseasonably warm nights with lows in the mid 60s to around 70 are expected. For reference, normal highs this time of year are in the low/mid 80s and lows in the lower 60s. Even with the daytime warmth, enough moisture left over Tuesday night could bring more patchy fog formation during the late night. Given uncertainly on coverage/density, left it as patchy this issuance. .LONG TERM...(Wednesday night through Sunday) Issued at 343 PM CDT Mon Sep 17 2018 One more day of very warm/hot and dry weather continues on Thursday, thanks to strong upper ridging in place across the southeastern CONUS. Highs should warm into the low 90s, with a few mid 90s very possible, especially across northern Alabama west of the I-65 corridor. The upper ridge will shift east of the region for the upcoming weekend, with weak troughing edging closer. E-SE winds on Thursday will become more southerly during Friday and the weekend. This will bring additional and deeper lower level moisture across the region. This moisture and accompanied daytime heating produced instability will return chances of showers and thunderstorms to the forecast - just in time for the weekend. The deeper moisture, along with more clouds than sun should result in slightly cooler temperatures going into the weekend. Stayed on a diurnal trend, with higher rain chances in the day and lesser at night for Saturday and Sunday. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 654 PM CDT Mon Sep 17 2018 VFR conditions will prevail at both terminals thru the period with the exception of some MVFR fog shortly before/around daybreak. Patchy fog will dissipate by 18/14Z, with a SCT deck of clouds developing AOA 4kft by midday tomorrow, lingering thru the end of the TAF period tomorrow evening. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...NONE. TN...NONE. && $$ NEAR TERM...RSB SHORT TERM...RSB LONG TERM...RSB AVIATION...12 For more information please visit our website at weather.gov/huntsville.