Area Forecast Discussion (AFD)
Issued by Huntsville, AL (HUN)
782 FXUS64 KHUN 150307 AFDHUN Area Forecast Discussion National Weather Service Huntsville AL 907 PM CST Thu Dec 14 2017 .NEAR TERM...(Tonight) Issued at 907 PM CST Thu Dec 14 2017 Mid/high cloud cover continues to gradually work its way nwd into more of the cntrl TN Valley this Thu evening. This cloud cover is embedded within a broad WSW flow regime in place across the wrn/cntrl Gulf regions, that should continue to inch further to the N into the early morning hrs Fri. Most of this cloud cover is also overspreading a reinforcing cold front that is now making its way into cntrl AL/GA. Other than possibly some lower level stratus developing shortly after daybreak Fri, no sig impacts are xpcted from this surge of mid level moisture to the ENE. Current temp trends range from around 30F across srn mid TN to predom the mid/upper 30s over N AL. Even with the mid level cloud cover, light sfc flow out of the NNW in the wake of the frontal passage should allow temps to fall near/just below the 30F mark across most of the area well after midnight. Other than adjusting overnight lows a couple of degrees based on the latest trends and increasing cloud cover just a bit, no major changes are needed to the ongoing forecast attm. .SHORT TERM...(Friday through Saturday) Issued at 307 PM CST Thu Dec 14 2017 Not much weather to speak of in the short term. A shortwave will move through the region during the day Friday, with a slightly cooler airmass building southeastward through the day. Cloud cover will persist through at least early afternoon and prevent some diurnal heating. Thus, temperatures will be a few degrees cooler than those observed today, with highs in the mid to upper 40s. Skies will clear overnight providing another cold night across the area, with lows on Friday dropping into the upper 20s once again. These cool conditions will be short-lived, however, as a weak ridge tries to build northward on Saturday as a shortwave moves ashore the west coast of Mexico. Meanwhile, high pressure will develop along the Gulf of Mexico, with surface winds shifting the south. The combination of southerly flow and height rises will help temperatures warm into the lower to mid 50s by Saturday afternoon. .LONG TERM...(Saturday night through Wednesday) Issued at 307 PM CST Thu Dec 14 2017 A pattern of ridging west, troughing east will change somewhat by the weekend and early next week, as a cut-off low off of the southwest coast induces troughing over the western third of the lower-48. This upper low situated across the southern Arizona border late Saturday night, will send a few upper level disturbances towards the north and east. It will bring unsettled weather across the Tennessee Valley, after midnight Saturday night. Temperatures, even over our far northern areas of Franklin and Moore in Tennessee should remain above freezing, so will keep the precipitation all liquid for now. More showers will overspread the Tennessee Valley during Sunday and Sunday night, with the best rain chances during Sunday morning, especially across northwest Alabama. General atmospheric instability parameters suggest it will be too stable for thunder, so am keeping the precip character as showers. As a few disturbances move across the region, scattered showers should continue on Monday and Tuesday. Shower activity should end Tuesday night as a cold front finally passes across the region, bringing drier air back into the region. Unlike the past few cold fronts, the air behind this one is not as cold, with lows "only" in the mid/upper 30s. The dry trend continues into Wednesday night. Another surge of moisture from the south should bring isolated showers on Thursday. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 540 PM CST Thu Dec 14 2017 VFR conds prevail for now at both main terminals, although mid/high clouds are approaching in a large swath from the S. Cigs in the 10-12K ft range look to develop after 06Z, and then lower more into the 5-7K ft range between 14-15Z Fri. Clouds may begin to sct late in the afternoon hrs. Light/var sfc winds will turn more toward the NW near 7-8KT Fri morning. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...NONE. TN...NONE. && $$ NEAR TERM...09 SHORT TERM...73 LONG TERM...RSB AVIATION...09 For more information please visit our website at weather.gov/huntsville.