Area Forecast Discussion
Issued by NWS Northern Indiana
Issued by NWS Northern Indiana
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075 FXUS63 KIWX 212320 AFDIWX Area Forecast Discussion National Weather Service Northern Indiana 720 PM EDT Fri Jun 21 2024 .KEY MESSAGES... * Dangerous heat and humidity will persist into Saturday. * There is a low chance (20-30%) for isolated storms this afternoon into early this evening across far ne IN, sc MI and far nw OH. * A cold front will bring better chances (50-80%) for showers and storms late Saturday night into Sunday morning, followed by dry and cooler (near normal) temperatures into Monday. && .DISCUSSION... Issued at 230 PM EDT Fri Jun 21 2024 Pooled moisture/instability near a loosely defined sfc trough may be enough to generate isolated afternoon convection in far ne IN, far nw OH and sc MI through early this evening. Similar to previous days, little shear/flow/forcing to speak of with non- severe pulse type cells favored (a few gusts > 40 mph). Dry and hot under a scattered diurnal cu field otherwise with a strong TN Valley centered upper ridge continuing to dominate. A series of shortwaves will track out of the Rockies into the Upper Midwest on Saturday, and through the Great Lakes Sunday into Monday. This will suppress the positive height anomaly southwest into the Southern Plains. Southwest flow will deepen in response to the approaching system tonight through Saturday evening, pushing the leftover boundary well north of the area with dry conditions and somewhat breezy southwest winds (gusts 20-25 mph on Sat). Highs on Saturday should push the mid 90s across the entire area with peak PM heat indices making one last run at 100F. Height falls through the Great Lakes will eventually force a cold front southeast through the area later Saturday night into Sunday morning with a better opportunity for showers and storms. Instability magnitudes will be limited given poor diurnal timing and meager mid level lapse rates. A weakening, outflow dominant, area on sub-severe convection likely survives into northern portions of the area later Saturday night in this environment, with the cold front off to the southeast by peak heating Sunday. Sfc anticyclone will briefly build in Sunday night into Monday behind Sunday`s cold front with a welcomed cooldown (seasonable temps). Theta-e ridge then tries to build in Tuesday into early Wednesday as warm advection ramps up in advance of the next approaching upper level wave, and behind the exiting sfc high. This pattern favors a few convective systems, and possible a very hot/muggy Tuesday, though confidence remains on the low side regarding PoPs and temps given lingering model differences. Dry and seasonable wx then to follow for the second half of the week. && .AVIATION /00Z TAFS THROUGH 00Z SATURDAY/... Issued at 720 PM EDT Fri Jun 21 2024 Substantial diurnal mixing and warm temps aloft will keep our area stable and dry through the period. Subtle boundary across Michigan will lift even further north on Sat as weak shortwave/ surface low approach. The associated cold front will bring a chance of storms after 00Z Sat night. SW winds will increase ahead of this system on Sat as well with gusts to 25 kts likely, especially at KSBN. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...Heat Advisory until 8 PM EDT /7 PM CDT/ Saturday for INZ005>008-012>015-020-022-023-103-104-116-203-204-216. Excessive Heat Warning until 8 PM EDT Saturday for INZ009-017- 018-024>027-032>034. Air Quality Alert until midnight EDT /11 PM CDT/ tonight for INZ020-103-203. OH...Excessive Heat Warning until 8 PM EDT Saturday for OHZ001-002- 004-005-015-016-024-025. MI...Heat Advisory until 8 PM EDT Saturday for MIZ078>081-177-277. MARINE...None. && $$ DISCUSSION...Steinwedel AVIATION...AGD