897 FXUS63 KDVN 302345 AAA AFDDVN Area Forecast Discussion...UPDATED National Weather Service Quad Cities IA IL 545 PM CST Tue Dec 30 2025 .KEY MESSAGES... - Light snow and probably patchy freezing drizzle in and near far northwest Illinois this evening, potentially resulting in slippery surfaces. - A clipper system will impact the area Wednesday mainly during the afternoon and early evening. Snow accumulations look to be an inch or less mainly north of I-80. - A slow warming trend will commence late this weekend and into early next week with temperatures trending above normal. && .UPDATE... Issued at 540 PM CST Tue Dec 30 2025 Between the two main clipper systems (the one earlier today and the one on Wednesday) there are a couple other weak upper disturbances traversing the same elevated baroclinic zone from Minnesota through northern Illinois. One such wave is just east of the Twin Cities early this evening and moving southeast, resulting in an enhanced area of low level warm air advection aloft (WAA) / isentropic ascent over southwest Wisconsin. Areas of light snow and patchy freezing drizzle have been observed upstream with this per obs including mPING reports. This forcing and attendant light precipitation will clip far northwest Illinois and likely immediate adjacent areas of eastern Iowa this evening, especially prior to 10 PM. Patchy slick surfaces are the concern and have handled with an SPS for now. Impacts in NWS La Crosse's area thus far have been minor, but keeping a vigilant watch on that and road conditions, and while unlikely it's not impossible that a short-lived Advisory is needed in the WI/IL border region area if impacts ratchet up. && .SHORT TERM /THROUGH WEDNESDAY/... Issued at 126 PM CST Tue Dec 30 2025 he first clipper system will exit the area this evening but clouds will be slow to break up overnight. Overall accumulations will be one half inch or less. Return flow developing ahead of the next system will help keep temperatures elevated overnight. Dry conditions are expected through the morning commute on Wednesday. Snow from the next clipper system should begin developing by late morning across the northern half of the area and overspread most areas along/north of I-80 during the afternoon. Snowfall amounts look to be under an inch across northwest Illinois with a dusting as far south and west as a Vinton, IA to Aledo, IL line. Given the timing of the snow on Wednesday, some minor impacts are possible during the evening commute for areas along/north of I-80. && .LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/... Issued at 126 PM CST Tue Dec 30 2025 Wednesday night Assessment...high (70-80%) confidence on colder than normal temperatures Lingering light snow from the Wednesday clipper system will end in the early evening followed by slowly clearing skies. The clearing skies and fresh snow for the areas that see it will allow temperatures to drop to colder than normal by sunrise Thursday. Thursday through Tuesday Assessment...low to medium (30-50%) confidence on mainly dry conditions. Medium to high (60-80%) confidence on a warming trend. The model consensus continues to show dry conditions with the main storm track north of the area. However, there are at least two weak upper level disturbances progged to move through the area; one Saturday and the other Sunday into Monday (depending upon the model solution). The Saturday disturbance has the better chance at only seeing an increase in clouds given the limited moisture. The Sunday/Monday disturbance is more questionable. Return flow develops on Sunday and continues into Monday. Some deterministic solutions are still hinting at very light precipitation developing while others do not. Most ensemble members continue to be dry which is pushing the model consensus to remain dry. Interestingly, the ECMWF-AIFS develops very light QPF side- swiping the area on Saturday while Sunday into Monday is dry. The AIGFS is the opposite; Saturday is dry with very light QPF Sunday into Monday. As mentioned yesterday, the signal is barely above the background error noise. We will need to observe the trend as the week progresses to see if the signal gets stronger or weakens. && .AVIATION /00Z TAFS THROUGH 00Z THURSDAY/... Issued at 540 PM CST Tue Dec 30 2025 The primary concern for the TAFs are light wintry precipitation this evening, light snow Wednesday, and gusty winds Wednesday. A minor upper level disturbance will traverse over very far eastern Iowa and northwest Illinois this evening, likely resulting in intermittent light snow and probably some light freezing drizzle for DBQ. There is a chance of this light wintry precipitation reaching as far south as MLI. Another more pronounced upper disturbance will move over the area mid-late morning Wednesday through the afternoon, again favoring DBQ and MLI, this time for light to briefly moderate snow. IFR conditions are probable at DBQ and possible at MLI. Light accumulations of one inch or less are presently expected. With that Wednesday system, winds from the west-northwest will increase with gusts over 20 kt in the afternoon (some 25+ kt gusts are possible mid-afternoon through early evening). && .DVN WATCHES/WARNINGS/ADVISORIES... IA...None. IL...None. MO...None. && $$ UPDATE...Friedlein SHORT TERM...08 LONG TERM...08 AVIATION...Friedlein