232 FXUS64 KHUN 100146 AFDHUN Area Forecast Discussion National Weather Service Huntsville AL 846 PM CDT Tue Apr 9 2019 .NEAR TERM...(Tonight) Issued at 845 PM CDT Tue Apr 9 2019 Regional satellite imagery shows almost all of the remaining cloud cover exiting NE AL as of 0130Z, as the parent upper low moves off the Atlantic coast. Very weak high pressure is building in its wake, with the next system of interest already beginning taking shape over the Plains. A weak front, marked primarily by a dewpoint gradient, is moving across the region from north to south. Clear to mostly clear conditions should continue overnight. A few cirrus are already beginning to spill into the Memphis metro area so some high clouds may manage to enter the region by sunrise. Fog is unlikely due to the drier air entering the region, but otherwise northerly winds will be light. Low temperatures in the mid 50s, with a few cooler spots, look to be in good shape. .SHORT TERM...(Wednesday through Thursday) Issued at 255 PM CDT Tue Apr 9 2019 Upper ridging will slide eastward through the day on Wednesday as a strong upper trough digs into the Plains. Winds initially to the north will quickly veer south by the afternoon and high pressure builds along the Gulf. The combination of rising heights, mostly clear skies and southerly flow will send temps into the upper 70s to lower 80s by Wednesday afternoon. The axis of the ridge will shift east of the TN Valley late Wednesday night, with southwesterly flow strengthening through the vertical column. This will make for a very mild night, with lows only falling into the lower 60s early Thursday morning. The aforementioned upper low and its surface cyclone will lift to the northeast and into the Northern Mississippi Valley during the day Thursday. Southerly flow will continue to strengthen as the pressure gradient tightens. The moisture return ahead of the associated cold front will be fairly sufficient and dewpoints will climb into the upper 50s by Thursday night. The timing of the actual cold front keeps precip west of the area during the day. Although clouds will increase slightly, temps will still warm into the upper 70s to lower 80s once again on Thursday. Showers will increase after sunset on Thursday as the cold front moves east of the Mississippi River. Given the northward extent of the upper low, height falls will be slow initially, keeping lapse rates from steepening too much. As the system continues its eastward progression, lapse rates will steepen some, and provide enough evaluated instability for embedded thunderstorms to move into the area. The kinematics and thermodynamics are not impressive with this system, so if anything, we will see a weakening light of showers moving through late Thursday night. The system continues to move through on Friday, with more details below. Temperatures overnight will be mild, as the clouds and rain prevent much cool, so lows will be in the upper 50s to lower 60s. .LONG TERM...(Thursday night through Monday) Issued at 255 PM CDT Tue Apr 9 2019 Models continue to show a strong storm system moving northeast from Iowa into the western Great Lakes region on Friday morning. This transports the bulk of the best moisture convergence and forcing north of the area on Friday in most models. The exception is the ECMWF, which seems to be the outlier and is much wetter than other guidance. With decent return flow only developing Thursday into Thursday night across northern Alabama, think the drier model trends may be more correct. A warm day is expected though despite some high cloud cover developing and some at least light precipitation moving into the area on the southern portion of the storm system. Highs in the lower to middle 70s look reasonable. Kept 30 to 50 pop in the forecast on Friday. Some isolated thunderstorms look possible but are not expected to be very strong. Most guidance pushes this front through northern Alabama and into central Georgia/Alabama Friday night. The exception again is the ECMWF, which stalls the front and precipitation over northern Alabama northeast into Virginia. Keeping with drier solution again during this period, but keeping a 20 percent chance of precipitation in the forecast Friday night. Lows should be cooler in the lower to mid 50s. Most models do move the front northward back over northern Alabama during the day on Saturday. Increase rainfall chances significantly to between 40 and 60 percent due to instability and the frontal boundary being draped over/near the area. At the same time a very strong upper low moves into Texas/Oklahoma late in the day on Saturday. During this period most guidance pushes the front just north of the area into central Tennessee. This might give northern ALabama a short break from shower and isolated thunderstorm activity. Both ECMWF and GFS phase this energy with a longwave trough axis moving towards the Upper Midwest/western Great Lakes region on Saturday night as it approaches and moves into eastern MS and western AL. This system could produce some strong to severe thunderstorm activity. Likely a QLCS type of setup, but still very far out to be very certain. Heavy rainfall between 1 to 2 inches (maybe locally higher amounts around 3 inches look possible). Some lighter lingering rainfall looks possible behind the front on Sunday along with cooler temperatures in the mid to upper 60s. Drier and slightly cooler temperatures are shown by models early next week as high pressure builds back over the area. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 642 PM CDT Tue Apr 9 2019 VFR conditions with mostly clear skies are expected thru 00Z/11. Winds will be light and out of the north overnight. There is a small chance of fog formation, but the humidity is not expected to be high enough to be included in the TAF. Winds will pick up out of the SE tomorrow; KMSL will become more SW after midday. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...NONE. TN...NONE. && $$ NEAR TERM...BCC SHORT TERM...73 LONG TERM...KTW AVIATION...BCC For more information please visit our website at weather.gov/huntsville.