FXUS63 KLOT 251114 AFDLOT Area Forecast Discussion National Weather Service Chicago/Romeoville, IL 614 AM CDT Sat Apr 25 2026 .KEY MESSAGES... - Severe thunderstorms Monday with all hazards possible, large hail, damaging winds and tornadoes. Heavy rain and localized flooding also possible. - Seasonable and dry conditions this weekend, but cooler temps near Lake Michigan. && .DISCUSSION... Issued at 144 AM CDT Sat Apr 25 2026 A cold front is currently moving across the area with brief patchy fog possible along the front. Low clouds are widespread across far eastern WI and much of Lake Michigan and are spreading southwest into northeast IL currently. Expect this trend to continue with a cloudy start to the day for at least northeast IL but these clouds are expected to lift and scatter by midday. Persistent northeast winds will allow for a large temp gradient across the area today, with highs in the lower 70s well inland to only the 50s near Lake Michigan. Low temps tonight will be in the mid 40s for most locations and then temps will rebound into the lower/mid 70s for much of the area Sunday, with another large gradient closer to Lake Michigan Sunday afternoon, as temps only reach the upper 50s near Lake Michigan. Primary forecast focus however remains the severe potential for Monday. Overall, no significant changes. Low pressure will move from the Plains Sunday to the western Great Lakes region Monday night, as it slowly deepens. Thunderstorms are expected to develop across eastern IA/northern MO Monday afternoon and move east across the local from mid afternoon through late Monday evening. As previously noted, appears the best chance of any discrete supercells will be across the southwest cwa (and areas west and southwest of our area), with an expected evolution into a squall line and potential QLCS tornado threat. Despite the fair/good agreement among the models, were still 60+ hours from the event and additional details/specifics are still to come. Heavy rain will possible with these thunderstorms and even with a possible fast moving line, with precipitable water values into the 1.5 inch range, there may still be rainfall totals of 1-2 inches. While the usual low-lying/urban flooding would be a concern with these amounts, if they were to materialize over the Rock, Fox or Des Plaines River basins, renewed rises would likely result. While it is far too early for a flood watch, did coordinate with WPC to include a slight risk for excessive rainfall, mainly for areas north of I-80, for Monday or day 3. There may be some wrap around showers Tuesday morning and then another cold front will move across the area Tuesday night, shifting winds northeast. Another weak system may move across the area Thursday bringing a few showers and additional cooler air. Low temps by the end of next week could be in the mid/upper 30s, thus frost potential will need to be monitored as this time period approaches. cms && .AVIATION /12Z TAFS THROUGH 18Z SUNDAY/... Issued at 614 AM CDT Sat Apr 25 2026 After a period of drizzle and LIFR cigs this morning, cloud bases in ongoing marine stratus are expected to gradually rise through the morning and then eventually scatter by early afternoon. Will advertise such a trend in the outgoing TAFs, though confidence is somewhat low on the exact timing of moving through flight categories (IFR to MVFR to VFR). Outside of cig trends this morning, winds are expected to prevail out of the northeast through the TAF period. Am noting a signal for a repeat performance of marine stratus tonight (perhaps even fog making it to the terminals). Will tuck in SCT006 starting at 03Z and let later shifts evaluate emerging trends. Borchardt && .LOT WATCHES/WARNINGS/ADVISORIES... IL...None. IN...None. LM...Dense Fog Advisory until 9 AM CDT this morning for the IL and IN nearshore waters. Small Craft Advisory until 10 PM CDT this evening for the IL and IN nearshore waters. && $$ Visit us at weather.gov/chicago