####018004252#### FXUS63 KIWX 152206 AFDIWX Area Forecast Discussion National Weather Service Northern Indiana 606 PM EDT Thu May 15 2025 .KEY MESSAGES... - Strong to severe storms are likely this evening into the early overnight (8 pm through 2 am EDT). All hazards possible. - Another round of showers and storms is expected late Friday afternoon into Friday evening. A few storms could become severe. - Warm temperatures through Friday will give way to cooler and drier conditions this weekend. && .DISCUSSION... Issued at 218 PM EDT Thu May 15 2025 High end severe threat (all hazards) remains in play this evening into the early overnight (8p-2a EDT) as any convection along an incoming dryline will have 35-40 knots of deep layer shear and 2000- 3000 j/kg of MLCAPE to work with. The low level jet also increases this evening with 0-3 km storm-related helicity pushing 250-300 m2/s2 for a tornado threat. There will also be sufficient CAPE in the hail growth zone/EML with supercells for large hail, with any organization into segments supporting a wind damage threat mid-late evening. Expectations are still for convective initiation (scattered discrete supercells) in ne IL between 21-00z, likely congealing into quasi-linear segments or clusters with eastward progression into the local area thereafter. Capping at the base of an EML, and more favorable deep ascent and low level convergence lifting through WI and MI, brings into question storm evolution/chances for areas south of the US 30 corridor. Much higher confidence in strong to severe storms breaking through the cap and tracking east through northern zones as weak height falls/cooling aloft clips the lower Great Lakes. Drier air briefly filters in behind the front later tonight into most of the day Friday with highs once again well into the 80s. Moisture does return northward late Friday into Friday evening in advance of a secondary cold front and mid level shortwave (70-80 kt 500 mb jet) arriving from the Mid MS Valley. This should be enough to generate a round of showers and storms mainly Friday evening with deep forcing, moisture quality, and deep layer shear magnitudes favorable for scattered strong to severe storms. Instability magnitudes are lacking when compared to this evening however with the primary moisture/instability reservoir likely suppressed closer to the OH River. Dry air on leading edge with a sub-cloud inverted-V profile and high DCAPE values may support good downdraft potential and localized wind damage if more robust cells develop, along with a hail threat given lingering steep mid level rates. Dry and cooler weather will filter in behind Friday night's wave in time for the weekend, with Saturday also breezy. Rain chances eventually return toward the middle of as the next western CONUS upper trough slows or cut-off over the Midwest. && .AVIATION /00Z TAFS THROUGH 00Z FRIDAY/... Issued at 601 PM EDT Thu May 15 2025 Minimal changes needed for the 00Z TAFs. The forecast is in great shape as we continue to monitor convection firing across the northern half of Illinois. We are expecting storms to enter Indiana around 00-01Z tonight and quickly move east/northeast. Given moderate to strong instability and ample shear, these storms will likely be strong to severe with a potential of some large hail and thunderstorm wind gusts in excess of 45 to 50 knots. A few tornadoes are also possible. Ceilings remain VFR for now but will likely drop to MVFR this evening as clouds increase and storms move through the area. Thinking 01-04Z is the best timing for storms at KSBN and 03-05Z at KFWA. Storms depart by 06Z, with decreasing winds and partly cloudy skies ahead for the overnight hours. Tomorrow, southerly winds will once again increase, with gusts to 20 to 25 knots. Storms are possible Friday afternoon, with the best chances south of US 24. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...None. OH...None. MI...None. MARINE...None. && $$ DISCUSSION...Steinwedel AVIATION...Johnson