055 FXUS63 KLOT 310831 AFDLOT Area Forecast Discussion National Weather Service Chicago/Romeoville, IL 231 AM CST Wed Dec 31 2025 .KEY MESSAGES... - Another round of accumulating snow expected today, while not much snow will accumulate, it could once again lead to hazardous road conditions. - Turning sharply colder tonight and Thursday, moderating back to near average for the weekend and possibly somewhat above average early next week. && .DISCUSSION... Issued at 231 AM CST Wed Dec 31 2025 Through Wednesday Night: Next clipper will zip across the area today with some more snow (and rain) followed by a fairly strong cold front tonight. Warm air advection has already pushed temps to around or just above freezing across our far southwestern CWA. With cloud cover and continued warm air advection, anticipate temps will remain steady or inch up a bit through sunrise. Temps will likely continue to rise through the morning and until the onset of precipitation with much of the CWA probably getting above freezing today, and likely some mid-upper 30s south of I-80. Dewpoints/wetbulbs are also progged to creep upward, so that may complicate precip type today. Speaking of precipitation, not much change in thinking from previous forecast with strengthening large scale ascent in the left exit region of a strengthening 130kt+ upper level jet likely to result in a blossoming area of precipitation late this morning or early this afternoon. As upper level ascent associated with the jet shifts east of the area later this afternoon, strengthening 900-700mb frontogenesis will likely keep precipitation going, though perhaps in a more banded fashion leading to some variability in precip amounts. Precip may start as rain or rain/snow mix as far north as the I-80 corridor with a race between how quickly temps will fall vs how quickly precip will end. This raises some doubts about how far south measurable snowfall will occur today. The warmer sfc temps should also result in lower snow:liquid ratios and some melting, at least initially, as snow falls. Overall, given the more marginal temps, today could end up being a less impactful snow than Monday's snow, even though amounts could be similar. Snow should end from northwest to southeast late this afternoon into early this evening not too long after cold front moves through. Pretty stout temp drop is expected this evening, but with gusty winds helping dry the pavement and left over treatment on pavement, we may escape any big re-freeze issues. Having said that, it will be something to watch as re-freeze, or black ice, events are notoriously challenging to predict. Winds will ease overnight, but crashing temperatures should still send wind chills plummeting into the single digits above zero to slight below zero at times northern CWA overnight tonight. - Izzi Thursday through Tuesday: As winds remain out of the northwest on Thursday, cold air will continue to funnel in to the area. Thursday will be the coldest of the next 7 days with high temperatures in the low-mid 20s south of I- 80 where some clearing is expected. Meanwhile, the remainder of the area is expected to get to the upper teens trying to get to the low 20s to the north under cloudy skies. With the persistent northwest flow, models are suggesting another weak wave may pass over the area. An isolated flurry is possible, but model soundings show a robust dry layer at the surface and low level subsidence. PoPs were kept well below 10% with the thinking that [if anything] it would likely be virga over in the afternoon. Another mid level trough currently analyzed off the San Diego coast will weaken and lift northward over the California Central Valley through Thursday. Models are suggesting a shortwave to eject from this trough Thursday night and travel eastward over Kansas into Friday morning. This wave is projected to phase with another weak, broad, moisture starved wave coming out of the Dakotas. As surface cyclogenesis develops over the Ozarks and provides precipitation for southern Illinois, winds locally will switch to the southeast and allow for some, relatively speaking, warmer air to lift northward in the morning providing moderate temperatures, before winds switch to the northeast in the late afternoon. Ensemble models continue to project that the upper level low over Ontario/Quebec will weaken and gradually move east, however there is still some disagreement among members in how much of it will weaken and move east. An upper level ridge develops over the Great Plains, there is a chance that broad northwest flow remains over the region. As another short wave trough develops over the weekend, the small adjustments in the Canadian low is keeping any impacts from the wave over Wisconsin. Perhaps a weak snow shower grazes the Wisconsin stateline, but confidence remains low at this distance. Temperatures should moderate nicely through the weekend. As that ridge continues to build early next week, high pressure will spread over the region and high temperatures will continue to gradually climb and become more mild with the chance that areas south of I-80 could see the 40s early next week. As high pressure dominates, we could be in for a quieter stretch in terms of precipition chance. DK && .AVIATION /06Z TAFS THROUGH 12Z THURSDAY/... Issued at 1103 PM CST Tue Dec 30 2025 Forecast concerns include... A period of snow Wednesday afternoon. Low mvfr, possible ifr cigs through early Wednesday evening. Gusty westerly winds turning north/northwest Wed afternoon. The current light snow will be ending from north to south over the next few hours. There may be a short period of patchy freezing drizzle as the precipitation ends, then the overnight hours are expected to be dry. There will be a chance of flurries after daybreak that will continue into the early afternoon when the next system arrives. Light snow is expected to develop over the terminals in the early afternoon and move south of the terminals by early evening. During this time period, there will likely be a narrow band of moderate snow with too much uncertainty to determine where exactly that will form. Prevailing ifr vis in the 1-2sm is expected with vis under 1sm wherever this band develops. There may be some lingering flurries into the early evening and then the rest of Wednesday night is expected to be dry. Low mvfr cigs are expected through early Wednesday evening, when cigs are expected to scatter out. Ifr cigs are possible overnight and again during the period of snow Wednesday afternoon but confidence is low for prevailing ifr cigs and for now, have included only scattered mention. Westerly winds are expected through early Wednesday afternoon with gusts into the 15-20kt range possible by mid/late morning. Directions will turn northwest during the period of snow and then shift to the north/northwest by early Wednesday evening. Gusts are expected to increase into the mid 20kt range during the afternoon and continue into the early evening. Its possible there may be some higher gusts into the 30kt range as well. Speeds/gusts will slowly diminish Wednesday night. Blowing snow is also possible Wednesday afternoon, but with temperatures expected to be near freezing during the falling snow, the snow may be a bit wetter. Thus, confidence is low for how much blowing snow may materialize. Its possible the snow may become drier/fluffy prior to ending. cms && .LOT WATCHES/WARNINGS/ADVISORIES... IL...None. IN...None. LM...Small Craft Advisory from 9 AM this morning to 3 AM CST Thursday for the IL nearshore waters. Small Craft Advisory from 9 AM this morning to 10 AM CST Thursday for Calumet Harbor IL to Burns Harbor IN. Small Craft Advisory until 3 PM CST Thursday for Burns Harbor to Michigan City IN. && $$ Visit us at weather.gov/chicago