


Area Forecast Discussion
Issued by NWS Northern Indiana
Issued by NWS Northern Indiana
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372 FXUS63 KIWX 122052 AFDIWX Area Forecast Discussion National Weather Service Northern Indiana 452 PM EDT Sat Jul 12 2025 .KEY MESSAGES... - Greatest chances for showers and storms today will be between 4-9 PM EDT. A few storms may be severe along and east of I-69 with threats for lightning, heavy rain, and isolated damaging wind gusts. - Hot and humid today with peak afternoon heat indices of 95 to 100 degrees, particularly in northwest Ohio. - Brief reprieve from high humidity with dry conditions Sunday and Monday, but heat is expected to return by Tuesday and Wednesday. - Wildfire smoke returns aloft Sunday and Monday. - Next best chances for rain/storms will be Wednesday and Thursday. && .DISCUSSION... Issued at 234 PM EDT Sat Jul 12 2025 An MCV coming out of southern Illinois this afternoon aided by lift from an approaching cold front will allow for scattered thunderstorm development this afternoon and evening. The cold front is currently draped from Rockford, IL southeast to St Louis, MO, however, a subtle wind shift is already preceding the front. Gravity waves leftover from last night`s MCS in Illinois have cleared the area and clearing is evident on visible satellite imagery. The forecast area should continue to destabilize with highs in the upper 80s to near 90 and dewpoints recovering in the low 70s. Heat indices are still expected to peak this afternoon between 95 and 100 degrees, especially across northwest Ohio. Destabilization should occur between 3-5 PM and clusters/a broken line of storms should form across central and northern Indiana. SPC has maintained their Slight Risk for northeast Indiana and northwest Ohio. The best window for severe weather should be along and east of I-69 from 4-9 PM EDT. There is only 20-25 kts of shear today and it is offset from a decent CAPE gradient with 2000-2500 J/kg SB CAPE across far northeast Indiana and into northwest Ohio. While the overall setup is unimpressive, steeping low level lapse rates coupled with ~1000 J/kg of DCAPE suggest that isolated damaging winds gusts could be possible this afternoon and evening if storms can maintain their updrafts. Even if storms are sub-severe, 40-50 mph gusts could still take down tree limbs and powerlines. Tonight, the cold front will slowly move through the area. Storms will taper off after sunset with the loss of diurnal heating. By sunrise on Sunday, the cold front should be mostly through the area. A few storms could redevelop south of the US 24 corridor in the afternoon and evening, but chances are very low (20% or less). Northwest flow behind the front will usher in a brief reprieve from the heat and humidity on during the afternoon on Sunday. Highs will be in the mid 80s with dewpoints only in the low 60s! Smoke from Canadian wildfires will also get dragged in across the Upper Great Lakes behind the cold front. An Air Quality Alert has been issued for southwest Lower Michigan from midnight EDT tonight through Noon EDT on Monday. Latest HRRR and RAP model runs depict that the smoke largely remains aloft over Lower Michigan and far northern Indiana, although increasing northwest winds may mix some of it down to the surface during the afternoon on Sunday. The relief from the heat and high humidity is, unfortunately, short lived. An upper level ridge and surface high pressure build across the Great Lakes region into early next week, bringing mainly dry conditions through midweek. Heat and humidity return with highs in the upper 80s Tuesday and Wednesday. The next best chances for rain/storms arrives Wednesday afternoon/evening and into Thursday as a low pressure system moves through the Midwest and Upper Great Lakes. && .AVIATION /18Z TAFS THROUGH 18Z SUNDAY/... Issued at 449 PM EDT Sat Jul 12 2025 The chance for thunderstorms has lessened across the area so they have been removed from both TAF sites. There is a small chance that flight conditions lower down into MVFR at FWA due to br, but have kept these conditions out of the TAF for now as a lack of a wet ground could preclude these conditions. Southwest winds this afternoon become more westerly for Sunday behind the front and struggle to reach 10 kts sustained. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...None. OH...None. MI...Air Quality Alert from midnight tonight to noon EDT Monday for MIZ078>081-177-277. MARINE...None. && $$ DISCUSSION...Johnson AVIATION...Roller