Expires:No;;350754 FXUS63 KILX 280403 AFDILX Area Forecast Discussion...Updated Aviation National Weather Service Lincoln IL 1003 PM CST Sat Dec 27 2025 .KEY MESSAGES... - Tonight into early Sunday morning, another round of fog may (30-50% chance) bring visibilities under 1/2 mile to portions of central IL. Those venturing out should allow extra travel time and stopping distance. - Scattered showers and thunderstorms will shift east across the area Saturday night into Sunday. There is a level 1 of 5 (marginal) risk for damaging winds with a line of storms near and east of I-55 between 2 and 7pm. - Expect an abrupt return to winter behind a cold front Sunday evening, with wind chills dropping below 0 by early Monday morning. This rapid plunge in temperatures may result in a flash freeze (icy conditions) on untreated sidewalks and roadways. - Strong west-northwest winds Sunday evening into Monday will make for difficult travel conditions for high profile vehicles. There is a 30-50% chance winds gust over 50 mph, potentially resulting in downed tree branches and localized power outages. && .UPDATE... Issued at 823 PM CST Sat Dec 27 2025 Updates this evening to temperatures and some transient patchy dense fog in the vicinity of a warm front lifting through central IL at this time. Have seen temperatures rise 4 to 5 degrees since sunset at Jacksonville, Springfield, Decatur, and Effingham along with a brief period of half mile visibilities that have gradually improved. Expecting sites along the I-74 corridor to see similar conditions later this evening. Otherwise, forecast is on track, as low pressure centered over western KS approaches, which will generate increasing showers and eventually thunderstorms Sunday morning. Temperatures will continue to trend upward overnight, with 60-65 degree readings from I-72 southward by morning, and mid to upper 50s to the north. 37 && .DISCUSSION... Issued at 212 PM CST Sat Dec 27 2025 ***** PATCHY FOG, SHOWERS TONIGHT ***** An expansive upper level ridge of high pressure over the nation's midsection will become increasingly amplified as it shifts east in advance of a deep trough tonight into tomorrow. Early Saturday afternoon, temperatures ranged from the mid 40s along the I-74 corridor to the low 50s south of roughly I-70. Conditions are much warmer south of the warm front, but that is progged to take until late this evening into the overnight time period to overtake central IL. As a result, daily high temperatures will likely be achieved just before midnight tonight for most of the area, with additional warming through Sunday morning, by which time temperatures are forecast to range from the low-mid 50s west of the IL River to low- mid 60s elsewhere. Complicating the temperature forecast somewhat, however, will be isolated (20-30% coverage) showers formed via isentropic upglide in the warm advection regime tonight. In addition, the moisture advection with the warm front should foster another round of (potentially dense) fog. 30-50% of HREF members forecast visibilities less than 1/2 mile from roughly 7pm to 5am, with dramatic improvement behind the warm front early Sunday morning; the one exception might be along I-74 where a few models (i.e., NAMNest, ARW) hold the warm front, and hence the fog, through most/all the morning. ***** STRONG STORMS SUNDAY ***** Between roughly 6 and 11am tomorrow morning, we'll also need to keep a close eye on radar, as both the HRRR and various REFS members are showing a couple feisty thunderstorms near the triple point and along the warm front across areas near and north of roughly I-72 (I- 74 east of Champaign). Though instability will be meager with poor mid level lapse rates (~6.5 C/km), the 0-3km SRH maximum of 400-600 m^2/s^2 near the sfc low and along the warm front could increase updraft strength and result in hail approaching severe limits in the strongest cells. Wind and tornado risks appear low with this activity given forecast soundings from virtually every model depict the instability as elevated, rooted around 800mb, but heavy rain could result in localized nuisance ponding of water in urban areas with various HREF/REFS members showing 1h rainfall over 1 inch in the heaviest cell(s). Despite cloud cover, continued warm advection via increasing south winds will ensure temperatures south and east of this convective activity will continue to climb through the morning. HREF suggests the highest chance (60-80%) for temperatures 65+ degF will be south of roughly a Springfield to Hoopeston line, where dewpoints will likewise surge into the low 60s to foster 500-1000 J/kg of (potentially uncapped) MLCAPE. This is the area of greatest concern for severe thunderstorms along the cold front during the afternoon and early evening, but it wouldn't take much for the instability to shift a little further west - hence, the marginal risk for severe weather extends back to roughly the IL River. Wherever that instability sets up, the high environmental shear (40- 50 kt in the 0-3km layer) will prove sufficient to sustain showers and storms. Given this shear is largely parallel to the line of storms (SW-NE) and the forcing for ascent along the cold front is exceptionally strong, we should have a solid line carrying mainly a 50-60+ mph wind gust risk. However, we can't completely rule out a brief QLCS tornado, especially with the richer low level moisture in southeast IL. Timing for this fast-moving, high-shear, low-CAPE (HSLC) line of showers/storms would be roughly 2pm along I-55 to 7pm along the IL/IN state line. ***** TURNING WINDY AND SHARPLY COLDER ***** Guidance is in strong agreement there will be rapid sfc cyclogenesis in the left exit region of the 125-140 kt 500mb jet Sunday evening into Monday morning, with general consensus in min pressures dropping from around 1000mb at noon to sub 980 in the wee hours of the morning Monday morning (approaching 20mb in 12 hours). As a consequence, the surface pressure gradient will quickly tighten across our area resulting in intense cold advection. Forecast soundings from various CAMs suggest that with the sharp pressure rises immediately following the cold front during the evening, mean PBL winds will increase to 30-40+ mph with top of channel winds anywhere from 45-55 mph area-wide - resulting in at least 1-3 hours of Wind Advisory-level winds at any given location. Then, the gradient will drive sustained 25-35 mph winds with sporadic gusts of 45+ mph through early Monday afternoon; some models even advertise some potential for a couple gusts approaching 60 mph Monday morning- early afternoon, with the highest chances (~20%) northeast of a Galesburg to Mattoon line. It's a bit early, but with guidance in agreement on the strong winds, we felt confidence was high enough (80-90%) in 45+ mph gusts to go ahead and issue a Wind Advisory today for areas north of a roughly Beardstown to Paris line; areas further south may need one too, but we'll wait until confidence increases before issuing there just yet. The other thing will be the abrupt drop in temperatures behind the cold front Sunday evening, with apparent ("feels like") temperatures dropping by as much as 20-30 degrees in under an hour in any given location. Wind chills will likely fall to anywhere between 0 and 10 below by sunrise Monday morning north of I-70, where they aren't forecast to climb out of the single digits until mid-late Tuesday morning. The rapid drop in temperatures following the cold front could result in a flash freeze on untreated surfaces, though the strong winds might help the recent rain to evaporate before freezing in most spots. We might also have some snow showers Monday morning, with forecast soundings showing a (near) saturated DGZ, steep low level lapse rates, and even some weak instability; we would be more concerned about snow squall potential, but at this time it appears the waning low level moisture should preclude anything heavy enough to cause major problems. Tuesday into Wednesday, global models and their respective ensembles are in general agreement that ridging in the Plains will attempt to nudge its way into the Midwest, but uncertainty increases in the forecast Thursday (New Year's Day) and beyond as another push of arctic air across the Great Lakes attempts to spill southward into our neck of the woods. It also appears a clipper system will impact some portion of the Midwest/Lower Great Lakes Regions Wednesday night into Thursday, but probabilities for measurable snowfall are highest to our north - only running 15-30% (highest along the I-74 corridor) in our area. Bumgardner && .AVIATION... (For the 06z TAFs through 06z Sunday Night) Issued at 1003 PM CST Sat Dec 27 2025 A warm front draped across the area will continue to lift north tonight, promoting LIFR cigs and LIFR to IFR vsbys initially, followed by subtle improvements in cigs/vsbys as the front moves farther north. Scattered showers will develop overnight as well, with a chance of thunderstorms mainly after 14Z until a cold front sweeps through around 20Z-23Z. Cigs expected to improved gradually after the cold frontal passage. Winds S 8-12 kts, shifting to W around 20 kts gusting over 30 kts developing by 20-23Z. West winds continuing to increase after 00Z, becoming 25 kts with gusts around 40 kts. 37 && .ILX WATCHES/WARNINGS/ADVISORIES... Wind Advisory from 3 PM Sunday to 6 PM CST Monday for ILZ027>031- 036>038-040>048-053>057. && $$