Area Forecast Discussion
Issued by NWS Northern Indiana
Issued by NWS Northern Indiana
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148 FXUS63 KIWX 181846 AFDIWX Area Forecast Discussion National Weather Service Northern Indiana 246 PM EDT Tue Jun 18 2024 .KEY MESSAGES... * There is a Marginal Risk for isolated severe storms in northwest Ohio this afternoon into early this evening. Gusty winds and heavy rain are the primary threats. * Hot, humid and mainly dry conditions are expected through Saturday, with the hottest days Thursday and Friday. Peak afternoon heat indices will approach 100 degrees, hazardous to sensitive and vulnerable groups. && .DISCUSSION... Issued at 246 PM EDT Tue Jun 18 2024 Warm/moist southerly flow will remain in place into tonight and Wednesday on the western periphery of a prominent upper ridge centered over the Mid Atlantic states. This will keep clouds and low rain/thunder chances in the forecast as Gulf of Mexico moisture continues to stream north into a lingering mid level shear/vorticity axis. For this afternoon/evening, will have to monitor areas mainly east of I-69 for widely scattered convection along a subtle convergence zone trailing a shortwave lifting northeast through lower Michigan. Moderate boundary layer destabilization and DCAPE up around 1200 j/kg suggests a low end threat for localized downbursts. Additional, low, chances for widely scattered showers/storms persist into tonight and Wednesday given the moist airmass and the potential for additional convectively induced waves to lift through. With that said, most locations will likely remain dry as the Mid Atlantic States upper ridge begins to flex westward. Heat indices are forecast to peak in the mid-upper 90s on Wednesday, but could once again be held down a bit by cloud cover. Confidence for PM heat indices nearing 100F increases into Thursday and Friday as the center of the aforementioned upper ridge expands west into the Ohio Valley. This will place the local area on the northern fringe of the heat dome with less cloud cover and highs well into the 90s. No changes were made to heat related headlines through Friday. Relief to temps/humidity more common for June still appears likely Sunday into early next week as an upper level trough and attendant sfc cold front swing east through the Upper Midwest and Great Lakes. The best chance for convection will be along the cold front on Sunday, though cannot rule out scattered convection Saturday afternoon/night given the potential for any pre-frontal features to sag south into an unstable/hot airmass. This and any cloud cover will determine if headline worthy heat indices will extend into Saturday as well. Confidence was too low to extend heat headlines into the weekend as a result. && .AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/... Issued at 128 PM EDT Tue Jun 18 2024 Cloud cover and limited heating, combined with a weakening low level jet has pretty much wiped out much of the area of rain and a few storms with only some widely scattered showers shown east of both sites. The challenge over the next several hours will be if there will be an uptick in coverage and intensity of showers/storms this afternoon and early evening. Convective temperatures are in the upper 80s, which with the breaks in the clouds and indications of some warming now under the strong June sun, appears attainable. As has been the case the past couple of days, no clear triggers in play to differentiate the best location for development. It could be argued that the remnants of the morning activity could help, but much of this may be too far east of KFWA to matter. Have removed the VCTS mention and went to VCSH for now and monitor trends. If something manages to pop up, it will likely be of short duration, something not captured well in the TAFs. After sunset, VFR conditions should prevail but can`t rule out a pop up shower at any point. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...Heat Advisory until 8 PM EDT /7 PM CDT/ Friday for INZ005>008- 012>015-020-022-023-103-104-116-203-204-216. Excessive Heat Warning until 8 PM EDT Friday for INZ009-017- 018-024>027-032>034. Air Quality Alert from midnight Wednesday night to midnight EDT Thursday night for INZ020. Air Quality Alert from 11 PM this evening to 11 PM CDT Wednesday for INZ103-203. OH...Excessive Heat Warning until 8 PM EDT Friday for OHZ001-002- 004-005-015-016-024-025. MI...Heat Advisory until 8 PM EDT Friday for MIZ078>081-177-277. Air Quality Alert from midnight tonight to midnight EDT Wednesday night for MIZ177-277. MARINE...None. && $$ DISCUSSION...Steinwedel AVIATION...Fisher