FXUS63 KIWX 030528 AFDIWX Area Forecast Discussion National Weather Service Northern Indiana 128 AM EDT Thu Jul 3 2025 .KEY MESSAGES... - Slight chance (10-20%) for a stray shower or storm Thursday afternoon. - Hot and humid Friday into this weekend. - More appreciable rain and storm chances (40-50%) return Sunday into Monday. && .DISCUSSION... Issued at 245 PM EDT Wed Jul 2 2025 A mid level impulse tracking east-southeast through the central Great Lakes will force a subtle (lake breeze enhanced) sfc trough into areas mainly along/north of US 30 late this afternoon into this evening. This feature may be enough to generate a stray shower or two as cooling aloft potentially breaks cap in place, but nothing more given the weak forcing and overall dearth of moisture and instability. Thursday will feature slight warmer conditions as heights rebound aloft in wake of this evening's shortwave. Boundary layer moisture/instability will also see a bit of an uptick near a boundary leftover across the Upper Midwest southeast into the lower Great Lakes. An isolated shower or storm could focus near this boundary and/or lake breeze during peak heating with PoPs limited in the 10-20% range given an overall lack of flow/shear/forcing, along with a tendency for dewpoints to mix out more than modeled for lesser MLCAPE magnitudes locally. A warmer, more humid air mass does become better established into Friday and Saturday as an Intermountain West upper ridge folds east into the Great Lakes and Ohio Valley. Friday is the transition day with high temps and PM heat indices dependent on any lingering convective cloud debris or outflow on the leading edge of the capped heat dome. Continued to cap PoPs at 10% (silent) with NBM's highs near 90 reasonable for now. Higher confidence in Saturday being the warmest day with PM heat indices in the mid 90s to near 100F under a mostly sunny sky as low levels moisten within increasing southwest flow. Guidance does continue to flatten the ridge into Sunday and Monday allowing an frontal boundary to drop into the vicinity with chances for scattered convection. && .AVIATION /06Z TAFS THROUGH 06Z FRIDAY/... Issued at 123 AM EDT Thu Jul 3 2025 VFR conditions will prevail through this TAF period. Light and mainly variable winds overnight periods but light diurnal winds become north-northwesterly during the day. Diurnal cumulus also will develop aoa 5 kft during the daytime. A low confidence for an isolated shower/thunderstorm especially for KSBN after 18z Thu but have opted to leave out of TAF forecast with the large uncertainty with the mainly pop-up scenario in place. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...None. OH...None. MI...None. MARINE...None. && $$ DISCUSSION...Steinwedel AVIATION...Andersen