591 FXUS63 KILX 052337 AFDILX Area Forecast Discussion NATIONAL WEATHER SERVICE LINCOLN IL 537 PM CST Fri Dec 5 2014 .SHORT TERM...(Tonight) ISSUED AT 258 PM CST FRI DEC 5 2014 20z/2pm surface analysis shows 1015mb low over northwest Oklahoma, with stationary frontal boundary extending northeastward into the Ohio River Valley. Widespread rain has been occurring along/north of this system throughout the day and is expected to continue through the evening. Latest radar mosaic is showing a large area of moderate/heavy rain with a few embedded thunderstorms across southeast Missouri into southern Illinois. Based on its E/NE trajectory, this area of precip will impact the SE KILX CWA over the next few hours. Have therefore decided to include isolated thunder mention south of I-70 this evening. Further north, a much lighter band of rain associated with the deformation zone of the system extends across central Illinois back across northern/central Missouri into eastern Kansas. This precip area will shift eastward and will ensure continued rain chances across the remainder of the CWA through the evening. As low pressure tracks into northern Kentucky by 06z, the rain will begin to come to an end from northwest to southeast after midnight. Have dropped PoPs entirely for locations west of the I-55 corridor after midnight, but have continued with categorical PoPs through the entire night along/south of I-70. Despite winds shifting to the north behind the departing system, persistent cloud cover will keep overnight low temperatures a few degrees above guidance numbers, ranging from around 30 northwest of the Illinois River to the lower 40s far southeast around Lawrenceville. && .LONG TERM...(Saturday through Friday) ISSUED AT 258 PM CST FRI DEC 5 2014 High pressure will build into the Midwest on Saturday, bringing cool and dry weather. Skies will initially be cloudy, but will clear from northwest to southeast as the day progresses. Even the usually more pessimistic NAM clears things out across most of the area by afternoon as strong synoptic subsidence/drying arrives behind exiting wave. The exception will be the far SE CWA, where clouds will likely hang on throughout the day. Given the morning cloudiness and a stiff northerly breeze, have gone slightly below guidance, with afternoon highs in the upper 30s to around 40 degrees. Skies briefly clear across the entire region Saturday night before clouds once again increase ahead of the next fast-moving system embedded within the prevailing zonal flow pattern. The system in question is currently evident on water vapor imagery off the coast of Oregon and is handled differently by the models as it moves across the country late in the weekend. The 12z NAM tracks the upper vort max eastward across the Northern Rockies Sunday morning, then dives it southeastward into the lower Ohio River Valley by Monday evening. Meanwhile, the GFS/ECMWF/GEM all keep the wave much further north across the Upper Midwest/Great Lakes. With the NAM being the odd model out, its solution has been rejected in favor of the model consensus. As a result, am expecting strongest lift to remain north of central Illinois as the feature skirts by to the north Sunday night into Monday. Forecast soundings are initially quite dry at all levels on Sunday, with only modest moistening from the top-down noted Sunday night. Ample dry air remains in place below 700mb through the entire period, so am skeptical about precip chances. Have cut back on the PoPs accordingly, with only slight chances across the northern CWA late Sunday night into Monday morning. If precip can overcome the low-level dry airmass and reach the ground, a light rain/snow mix can be expected. Once this system passes, another shot of cooler air arrives for Tuesday and Wednesday, resulting in highs only in the 30s. After that, all signs are pointing to a deep trough digging across the western CONUS by the end of next week. Corresponding downstream ridging across the Plains/Midwest will lead to a warming trend with highs climbing well into the 40s by Friday and perhaps even higher next weekend. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) ISSUED AT 525 PM CST FRI DEC 5 2014 IFR/LIFR conditions with some local VLIFR cigs/vsbys are expected to continue thru the overnight hours before we see a very slow improvement in cigs on Saturday as the storm system shifts off to our east. A large band of rain continues to track east northeast into our area this evening and we really don't see much change in that overnight as the storm approaches from the south. Further north towards Peoria, there may be some tempo breaks in the IFR cigs to MVFR but at this time am not expecting it to last. Forecast soundings off the short term models not very optimistic with respect to clearing on Saturday in the wake of the storm system and with boundary layer winds still forecast to be out of the north to northeast during the day, that may be the way to go so will continue to keep at least MVFR cigs going into the afternoon hours. Surface winds will be out of the east and then trending more northeast later tonight and during the day on Saturday with speeds increasing a bit to 10 to 15 kts with a few gusts near 20 kts, especially near BMI and CMI. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Barnes LONG TERM...Barnes AVIATION...Smith