268 FXUS63 KIWX 211850 AFDIWX Area Forecast Discussion National Weather Service Northern Indiana 250 PM EDT Tue Oct 21 2025 .KEY MESSAGES... - Lake enhanced rain showers increase in coverage this afternoon and evening, persisting off and on (especially north of US 6) through Thursday morning. - West/northwest winds could gust as high as 30 to 35 mph this afternoon/evening through the day on Wednesday. - Below normal temperatures persist through the week ahead. Highs Wednesday and Thursday struggle to get out of the low 50s. - Widespread frost/freeze is likely Friday morning with temperatures in the low to mid 30s. - The active weather pattern and below normal temperatures continue through the weekend and into early next week. && .DISCUSSION... Issued at 249 PM EDT Tue Oct 21 2025 A deepening low pressure system is currently centered over Lake Superior. With a closed low aloft and good upper level support, this system is expected to spin across the Upper Great Lakes region for the next few days. The center of the low will gradually shift southward over the eastern UP and northern Lower Michigan, providing clouds, gusty winds, and periods of lake enhanced rain showers across our CWA from this afternoon through midday Thursday. With a tightening pressure gradient due to the deepening low, west/northwest winds may gust as high as 30 to 35 mph at times later today through Wednesday. Diurnally driven rain showers downwind of Lake Michigan are expected to increase in coverage later this afternoon and into the evening. At times, pockets of strong 500mb vorticity pinwheeling around the center of the low will aid in lift and potentially allow for a few thunderstorms to develop too. While strong low level lapse rates of 8C/km or greater will work in conjunction with cold air aloft to sustain these storms, instability is lacking (only up to 250 J/kg SBCAPE across southern Lower Michigan) so thunderstorm activity is expected to be quite isolated. Today will be an active day but likely not a hazardous weather day. If anything, small graupel and gusty winds of 40 mph will be the main hazards. Tonight, the best chances for continued lake enhanced showers will be north of US 6 where continued lift, CAA, and low level convergence will be best. Below normal temperatures last through much of the upcoming week. The aforementioned midweek system and gusty winds will allow for cooler temperatures to prevail across the Great Lakes region. Wednesday and Thursday will be the coolest days of the week with highs struggling to make it out of the low to mid 50s. The low pressure system finally exits the Great Lakes region, which allows for drier air to build in during the day on Thursday. The first widespread frost/freeze of the fall season is likely Thursday night; Lows will likely be in the low to mid 30s area-wide by daybreak Friday and again on Saturday morning. The active fall weather pattern looks to continue this weekend and into early next week. A developing low pressure system across the Mid Mississippi valley may yield some scattered low chances for rain over the weekend, with better chances for rain arriving Monday and Tuesday as yet another low pressure system traverses the central Plains and into the Upper Midwest. Temperatures will continue to be below normal into early next week. && .AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/... Issued at 1255 PM EDT Tue Oct 21 2025 Strong vort lobe and associated secondary cold front will swing through northern IN this afternoon with scattered showers and perhaps an isolated storm or two. Gusty west winds and small hail may accompany more robust showers. It will be breezy and VFR otherwise into early this evening. Lake effect rain showers will impact KSBN tonight into tomorrow on the southern fringes of a large low pressure system. Cigs should lower into MVFR here. Lower rain chances away from the lake at KFWA with cigs potentially lowering into high MVFR for a time later tonight into Wednesday morning. Breezy west winds linger otherwise. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...None. OH...None. MI...None. MARINE...Gale Warning until 8 PM EDT Wednesday for LMZ043-046. && $$ DISCUSSION...Johnson AVIATION...