Area Forecast Discussion
Issued by NWS Northern Indiana
Issued by NWS Northern Indiana
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676 FXUS63 KIWX 192312 AFDIWX Area Forecast Discussion National Weather Service Northern Indiana 712 PM EDT Wed Jun 19 2024 .KEY MESSAGES... * There is the potential for isolated strong to severe storms this afternoon into early this evening in northwest Ohio, northeast Indiana and south-central Michigan. Damaging winds appear to be the primary threat. * Hot, humid and mainly dry conditions are expected through Saturday. Peak afternoon heat indices will approach 100 degrees in many locations, hazardous to sensitive and vulnerable groups. && .DISCUSSION... Issued at 223 PM EDT Wed Jun 19 2024 Gulf of Mexico moisture streaming north on the western fringe of a persistent Mid Atlantic centered upper ridge has kept mid-high clouds and even a few showers/storms around so far today. Similar to yesterday, this has provided some relief from the heat/humidity, though satellite and model trends favor a trend toward a partly cloudy skies and heat indices into the 90s this afternoon. Isolated to scattered showers and storms will be the focus otherwise this afternoon into early this evening, especially along and east of I-69 where a mid level shear/moisture axis and area of subtle convergence in the low levels linger. Lacking shear and forcing will once again limit storm coverage/chances, but juicy airmass and DCAPE values near 1000 j/kg suggest that a collapsing pulse storm could produce a localized downburst. Drier sinking air does advect into the area into Thursday and Friday as the strong Mid Atlantic upper ridge retrogrades west- southwest into the OH and Mid MS Valley. This process should force the primary moisture channel to the west and north during this time with less cloud cover and higher probabilities of experiencing peak PM heat indices near 100F. Subtle shortwaves and weak sfc outflows/lake breezes could be enough to activate isolated convection during the afternoon hours each day (20-30%), mainly north of US 30, with most locations remaining dry/hot. For the weekend, an upper level trough and associated sfc reflection will release east-southeast through the Upper Midwest and Great Lakes. The local area will no doubt be in the breezy and hot warm sector on Saturday in advance of the approaching system, though cannot completely rule out a few late day storms if any pre-frontal features sag south into this unstable and humid airmass. The heat will remain the story otherwise on Saturday with headlines potentially needing expansion at some point. The primary cold front and best opportunity for more organized rain/storms is still favored late Saturday night through early Sunday afternoon, though differences in moisture quality and timing remain within 12z guidance. A brief respite from the heat and humidity remains in the cards post- frontal into Sunday night and Monday with temperatures more common for late June. The southern Great Lakes then look to become positioned on the northeastern fringe of a building upper ridge by Tuesday and Wednesday with ring of figure type convective systems in the vicinity. && .AVIATION /00Z TAFS THROUGH 00Z THURSDAY/... Issued at 712 PM EDT Wed Jun 19 2024 Hot and humid airmass supporting ample clouds with isolated showers/storms though ceilings remain above 5 kft. KFWA will continue to have the better chances given higher moisture/ instability but will hold with VCSH given very low confidence in impacts to the terminal. Shower activity should slowly wind down with the loss of daytime heating. Calm winds anticipated overnight and models suggest some patchy fog or low stratus may develop. Some BR is possible but confidence in any significant impacts is too low to include in the TAF`s. Another round of isolated convection is expected tomorrow afternoon/evening as hot/humid airmass remains. && .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 tonight to midnight EDT Thursday night for INZ020. Air Quality Alert until 11 PM CDT Thursday 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 until midnight EDT tonight for MIZ177-277. MARINE...None. && $$ DISCUSSION...Steinwedel AVIATION...AGD