294 FXUS64 KHUN 101100 AFDHUN Area Forecast Discussion National Weather Service Huntsville AL 600 AM CDT Thu Sep 10 2020 .UPDATE... For 12Z TAFS. && .NEAR TERM...(Today) Issued at 306 AM CDT Thu Sep 10 2020 High pressure over the Southeast this morning will break down through the day today as a weak tropical disturbance currently over Florida makes its way westward along the Gulf Coast. This disturbance will enhance easterly flow and moisture advection into the Tennessee Valley from the Atlantic, allowing for a few showers and thunderstorms to develop this afternoon, mainly east of I-65. Skies, mostly clear this morning, will start to cloud up over Northeast Alabama and southern Middle Tennessee this afternoon, which will show this breakdown occurring of the pattern that's been overhead for the last several days. Even through we will see more clouds and a chance for a few showers, highs today will still reach up into the upper 80s to lower 90s. .SHORT TERM...(Tonight through Saturday) Issued at 306 AM CDT Thu Sep 10 2020 We will continue to see easterly flow bring additional moisture into the Tennessee Valley on Friday, which will spread the chance for showers and thunderstorms westward across all of Northern Alabama and southern Middle Tennessee. Meanwhile, a large upper-level trough moving across the Midwest starts its approach. With the approaching trough and a building broad region of high pressure centered off the coast of the Carolinas, flow will turn more southerly on Saturday. This will bring in greater amounts of moisture and a more unstable air mass for Saturday afternoon and evening showers and thunderstorms. Expect greater coverage and heavier rain with showers and thunderstorms on Saturday. Also, with more rain and higher humidity, temperatures may actually be a couple degrees cooler on Saturday, though it may not feel that way. .LONG TERM...(Saturday night through Wednesday) Issued at 306 AM CDT Thu Sep 10 2020 At the start of the extended period, a somewhat amplified pattern over the lower-48 will become more zonal along the United States and Canadian border. An upper low current over the 4-Corners region, will by Sunday morning be a flattening trough transitioning to the east across the Great Lakes region. Another item of interest is a tropical system nearing Bermuda from the SE. All model output was in agreement with the flattening trough picking up that system, keeping away from the East Coast. An upper low over far northern Canada, part of a general vortex of other lows rotating around Greenland, will move SSE towards the Hudson Bay by the middle of next week. During this time, inter-model disagreement becomes very noticeable in the development of this low, and another system moving across the western states during this time. This leads to a rather low confident forecast far as details for the first half of next week. Stayed with blends for the most part to smooth out any peaks and/or minimal values the deterministic models were coming out with. Regarding features, the models were in generally agreement bringing a weak cold front across the area late Sunday into Monday. The passage of this boundary, along with high precipitable water amounts (averaging over 2 inches from Sun-Mon) will bring numerous showers and thunderstorms. High moisture levels could yield locally heavy rainfall in some of the showers. This rain along with possible heavy amounts on Sat may produce minor flooding and/or hydrological issues early next work week. Our eastern areas would be more prone for flooding as they should get the higher rain totals into early next week. With the passage of the front, temperatures will cool off more as we go into the new week. Daily highs in the upper 80s on Sun, should cool down into the lower 80s on Wed. Despite the front moving across the region; it will hang up and become stationary south of the area. More upper level disturbances moving to the NE from the northern Gulf, will bring more showers and thunderstorms, creating a rather unsettled work week. Model differences really show after the midweek. The ECMWF had deepened the Canadian low more than the GFS, with it hinting at another stronger front and a northerly flow late in the week, while the GFS stayed with a southerly flow. Better solutions will come from later runs closer to this timeframe. && .AVIATION...(For the 12Z TAFS through 12Z Friday morning) Issued at 600 AM CDT Thu Sep 10 2020 VFR conditions expected through the TAF period. Clear skies this morning, but expect a few clouds to develop mainly over northeast and north-central Alabama this afternoon. May see a couple showers in these areas as well, but probability is very low that a shower or thunderstorm will impact either HSV or MSL this afternoon, so not in TAF. Winds light and variable this morning will become more northeasterly this afternoon before weakening and becoming variable again this evening. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...NONE. TN...NONE. && $$ NEAR TERM...McCoy SHORT TERM...McCoy LONG TERM...RSB AVIATION...McCoy For more information please visit our website at weather.gov/huntsville.