


Area Forecast Discussion
Issued by NWS Northern Indiana
Issued by NWS Northern Indiana
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109 FXUS63 KIWX 162321 AFDIWX Area Forecast Discussion National Weather Service Northern Indiana 721 PM EDT Thu Oct 16 2025 .KEY MESSAGES... - Mild Friday and Saturday with highs in the 70s to low-80s by Saturday - Increasing rain and thunderstorms chances Saturday afternoon (70-90% chance) through Sunday morning. - Breezy this weekend with wind gusts near 30 mph, perhaps as great as 40 mph at the lakeshore Sunday. && .DISCUSSION... Issued at 232 PM EDT Thu Oct 16 2025 An upper-level ridge, currently over the Central Plains, slides east through the remainder of the week resulting in a gradual warm up. A weak warm front is lifting through Illinois this afternoon and this could spark a couple of rain showers tonight along the Michigan state line. Preexisting airmass is rather dry and the best upper- level forcing is displaced to our west. To the west of this ridge is a swirling area of low pressure which lifts north- northeast and become the primary focus for this forecast package, as its cold front approaches Saturday. This morning`s suite of model guidance has come into better agreement with timing and amplitude of the anticipated upper-level low. Saturday begins dry before the chance of showers and thunderstorms increases from west to east in the afternoon. Instability continues to be a limiting factor for the marginal severe weather risk. Forecast soundings reveal a stout elevated mixed layer that guidance suggests will be overcome for the afternoon; not quite a slam-dunk solution. But this sounding also reveals MUCAPE of less then 200j/kg, in contrast to 0-6km shear in excess of 30 knots, and yes, even looping low-level hodographs. NAM forecast soundings are the most robust with MUCAPE exceeding 500 j/kg. While some ingredients are in place, how quickly we can destabilize and whether or not Gulf Coast convection will inhibit poleward moisture transport are elements that remain to be seen, and will likely not show their hand until Saturday morning. The low-level jet ramps up considerably Saturday night with some guidance suggesting 50-knot winds at 925mb. With stratiform rain ongoing, this jet will generally fail to mix down. However, as the surface low departs and deepens, breezy northwest winds should develop Sunday. Wind gusts near the lake shore could gust to 40 mph. Sharply colder Sunday with some locations trapped in the upper-50s as deep trough spreads over the Great Lakes. How this trough evolves beyond Sunday is unclear, with considerable spread noted in how cyclogenesis occurs in response to an incoming shortwave. Additional beneficial rain fall is possible (20-40% chance). && .AVIATION /00Z TAFS THROUGH 00Z SATURDAY/... Issued at 722 PM EDT Thu Oct 16 2025 Increasing warm/moist air advection aloft will bring an increase in high clouds through Friday but low levels remain dry and VFR conditions will prevail. Surface winds will also steadily veer to a southerly direction by Friday morning but remaining around 10 kts or less. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...None. OH...None. MI...None. MARINE...None. && $$ DISCUSSION...Brown AVIATION...AGD