


Area Forecast Discussion
Issued by NWS Northern Indiana
Issued by NWS Northern Indiana
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437 FXUS63 KIWX 092326 AFDIWX Area Forecast Discussion National Weather Service Northern Indiana 726 PM EDT Wed Jul 9 2025 .KEY MESSAGES... - Scattered showers and storms this afternoon and evening. Heavy rain, lightning, and gusty winds will be possible in any storms. - Dry tonight with potential for patchy fog to develop Thursday morning. - There is a High Swim Risk for southeastern Lake Michigan beaches today through early Thursday morning. Stay out of the water! - Hot and humid by the weekend with chances for rain/storms. && .DISCUSSION... Issued at 223 PM EDT Wed Jul 9 2025 A cold front is located from Grand Rapids southwest towards Des Moines, and it will slowly sink south and east this afternoon and evening. Ahead of the front, destabilization is already occurring across our forecast area. A growing cumulus field is evident on visible satellite imagery and showers have been percolating throughout the area already today. Because of cloud cover across much of the area, temperatures have struggled to get out of the 70s today. Scattered multicell clusters of showers and a few storms are ongoing east of IN 49, while a lake shadow is keeping conditions dry along the lakeshore. Additional diurnally driven showers and storms will be possible until sunset. Much like setups over the past few weeks, it will be feast or famine for storms. Some locations may get nothing while others get several inches of rain in a short amount of time. The Storm Prediction Center has maintained a Marginal Risk (level 1 of 5) for the far northeast portion of the forecast area, meaning a few storms could be strong to severe today. The setup for severe weather appears fairly unimpressive as there is ample instability for storms to work with (2000-2500 J/kg SBCAPE), but no source of lift (until the front arrives) and little to no shear in place as vertical wind profiles are unidirectional out of the southwest. Confidence in severe weather is very low. Given ample low level moisture (dewpoints in the 70s) and high PWATs of 1.5-1.75", flooding is a much more likely scenario today than severe weather. Backbuilding will be possible with low level low from the west/southwest parallel to the boundary and slow Corfidi upshear winds. Precipitation rates should be very efficient today given long, skinny CAPE profiles, a deep warm cloud layer, and PWATs above the 75th percentile of normal. WPC has much of the area in a Marginal Risk (level 1 of 4) for localized flash flooding, which definitely is plausible given the favorable environment. Additionally, there is a High Swim Risk for southeastern Lake Michigan beaches today through early Thursday. As winds switch from the southwest to northwest/north along the lakeshore behind the cold front, waves will build to 3 to 4 feet. Strong rip, structural, and longshore currents will all be possible, especially on the north side of piers. Stay out of the water! winds will shift to be coming from the northwest after the front passes through and skies will start to clear out. Forecast soundings show an inversion developing tonight as well as a stable airmass moves in. With mostly clear skies, light winds, and residual ground moisture, patchy ground fog may develop Thursday morning. Confidence is medium in fog developing, but low as to the extent of visibility impacts. Thursday will be dry as high pressure briefly builds into the Upper Great Lakes region for 24-36 hours. An upper level ridge expands across the southwest and central US this week and progresses eastward. Heat and humidity will build across the Midwest as the upper level ridges expands and WAA increases later in the week. Depending on where the periphery of the ridge sets up and how much destabilization occurs, we could see some showers/storms on Friday. Better chances for rain/storms arrive by the weekend as another cold front moves through, although long term models disagree on exact timing and positioning. && .AVIATION /00Z TAFS THROUGH 00Z FRIDAY/... Issued at 720 PM EDT Wed Jul 9 2025 Scattered showers and a few thunderstorms continue this evening in the warm sector of an approaching low over eastern Michigan. The main boundary has pushed southeast of KSBN, so mostly clear skies can now be expected for the rest of the night. There is some potential for shallow fog towards morning as winds die down. Confidence is low, but did include an MVFR Tempo group. Showers and storms will persist near KFWA for the next couple of hours, but will diminish as instability lessons with the loss of daytime heating. In the wake of showers and storms, fog appears to be increasingly likely with renewed low level moisture, weak flow, strong model concensus and a slow-moving front. Dry conditions are expected for Thursday, with just some scattered mid-level clouds developing in the afternoon. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...Beach Hazards Statement until 1 AM CDT Thursday for INZ103. OH...None. MI...Beach Hazards Statement until 2 AM EDT Thursday for MIZ177-277. MARINE...None. && $$ DISCUSSION...Johnson AVIATION...Brown/Cobb