436 FXUS63 KIWX 290500 AFDIWX Area Forecast Discussion National Weather Service Northern Indiana 100 AM EDT Mon Jun 29 2026 .KEY MESSAGES... - Extreme Heat Warning in effect Monday afternoon into Thursday evening for an extended period of high heat indices and limited nighttime cooling. - Heat may remain a concern Friday, but chances for showers and thunderstorms begin to increase resulting in lower confidence on the amount of impacts. && .DISCUSSION... Issued at 238 PM EDT Sun Jun 28 2026 BLUF...after extensive collaboration with surrounding offices, we have decided to upgrade to an Extreme Heat Warning for the same valid period as the watch. Will break down the pros and cons shortly. We want to reiterate that regardless of the type of heat related headline, they all convey the same thing...a focus on the impacts of the heat to everyone. In addition to sensitive populations, even those that routinely work outside or have A/C will be impacted Warming today has been somewhat limited by high clouds blowoff from a persistent MCS to our west as well as some cu popping here and there across the area. Radar and satellite data showing the complex finally beginning to weaken. While the remnants could bring a quick shower to northern portions of the area later this afternoon or early evening models generally lean toward no impacts so pops will be left below 15%. Additional upstream complex are expected over the next day or 2, but should remain well north of the forecast area. We then turn our attention to the bigger story of the dramatic arrival of summer and extended period of increased heat and humidity. A mixture of headlines surround us which may pose challenges to our media partners in messaging. Monday will be the "coolest" of the next several days with many offices leaning toward handling this with a Heat Advisory and then look at a Watch or eventual Warning in the later periods. For our area, even though the same concerns exist, it was decided to keep messaging simple and just upgrade to a warning for the extended period of impacts with heat indicies AOA 100 degrees. There are factors that could cause true criteria from being met at times both Monday and Thursday, but it is the cumulative effects of heat and humidity, combined with limited overnight cooling, that pose the greatest danger. Some model trends are indicating the upper ridge may not fully settle over the area and could shift east a bit faster to allow at least the chance for a bit of convection. Friday may need headlines as well, but concerns for either convective development across the area or upstream complexes propagating into the region lead to greater uncertainty. With the focus on the heat, little will be addressed for now on the holiday weekend other than it will remain on the warmer side with additional potential for showers and storms at times. && .AVIATION /06Z TAFS THROUGH 06Z TUESDAY/... Issued at 100 AM EDT Mon Jun 29 2026 Upper-level low is drifting ESE this morning and along with it, a narrow area of showers and thunderstorms. This will avoid the terminals and generally, VFR BKN ceilings will persits most of the day before becoming SCT/FEW. Increasing pressure gradient after sunrise with a modest area of low pressure noted over the Central US, at odds with 1017mb high pressure over the eastern Great Lakes. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...Extreme Heat Warning from 2 PM EDT /1 PM CDT/ this afternoon to 8 PM EDT /7 PM CDT/ Thursday for INZ005>009-012>015- 017-018-020-022>027-032>034-103-104-116-203-204-216. OH...Extreme Heat Warning from 2 PM this afternoon to 8 PM EDT Thursday for OHZ001-002-004-005-015-016-024-025. MI...Extreme Heat Warning from 2 PM this afternoon to 8 PM EDT Thursday for MIZ078>081-177-277. MARINE...None. && $$ DISCUSSION...Fisher AVIATION...Brown