


Area Forecast Discussion
Issued by NWS Northern Indiana
Issued by NWS Northern Indiana
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811 FXUS63 KIWX 181630 AFDIWX Area Forecast Discussion National Weather Service Northern Indiana 1230 PM EDT Sat Oct 18 2025 .KEY MESSAGES... - Showers and scattered thunderstorms will develop across areas mainly north of US 24 this afternoon. - Thunderstorms today may become marginally severe and produce strong to locally damaging wind gusts this afternoon into early tonight. - Rain will be heavy at times tonight through Sunday. Total rainfall amounts may exceed 2 inches in some areas northwest of Fort Wayne. - Becoming breezy today with wind gusts up to 30 mph. Windy Sunday with wind gusts to 40 mph Sunday. && .UPDATE... Issued at 1026 AM EDT Sat Oct 18 2025 There continues to be the marginal risk of severe thunderstorms this afternoon and the overall forecast remains on track. Start time for thunderstorms is within the 2pm to 5pm EDT window, with a slight preference toward the 5pm start time. Compared to 24 hours ago, it appears north of US 24 may be the area of interest, even as far north as South Bend and Angola. Isolated thunderstorms may develop in those areas on a lingering outflow boundary from morning showers that fizzled out. Upper-level support this afternoon comes from a departing 500-mb jet (right entrance region) and an incoming 850mb jet (left exit region). Cloud cover is thin upstream which ought to permit ample destabilization. 60-degree dew points are already seeping in along the IN-IL line. Southern areas have the risk of severe storms closer to sunset from any lingering activity existing west- central IN. Hodographs appear linear in nature and LCLs remain high (1500m) which lessens confidence in any tornado risk. Thus, damaging wind gusts remain the primary severe weather hazard amid this highly sheared environment and steep low-level lapse rates. && .DISCUSSION... Issued at 108 AM EDT Sat Oct 18 2025 A pair of upper level trofs will approach from the west today and then merge just upstream of the forecast area. This new merged system will have a lot of energy in the base of the upper level trof with 500 mb winds > 100 kts. Mid level lapse rates do not appear very steep; however, low level shear and very strong upper level winds should create an environment for marginally severe storms. Wind gusts from 45 to 55 mph with at least the stronger storms this afternoon into this evening appears reasonable. Locally heavy rainfall is likely with most of the storms. The PWAT anomaly will be around +1.00" for an extended time from this morning through most of tonight. While the antecedently dry conditions do not favor flooding, it looks like the chances for any flooding should be confined to mainly urban areas - especially those that are more prone to flooding. Low level moisture at the surface was meager early this morning with dew points almost exclusively in the 40s. Winds had already become south around 10 mph ahead of the front and associated developing surface low pressure area. Low level moisture will surge north of the Ohio River and east of the Mississippi River today as the system approaches. The latest GFS BUFKIT has CAPE values this afternoon < 200 J/Kg; however, the 00Z NAM is much more unstable with afternoon CAPEs topping 1000 J/Kg. In light of the GFS and SREF soundings, the NAM does appear to have a better handle on afternoon low level heating with surface temperatures southeast of the front around 80 degrees to the lower 80s. All considered, the chance for marginally severe storms appears reasonable given the changes expected in the low level thermal environment and wind fields. This environment should be able to support strong to locally damaging wind gusts by late this afternoon. Chilly air will spread across the forecast area behind the main system. High temperatures Tuesday and Wednesday are expected to only be in the 50s. There is a good chance for frost Wednesday night before temperatures recover closer to normal. && .AVIATION /18Z TAFS THROUGH 18Z SUNDAY/... Issued at 1230 PM EDT Sat Oct 18 2025 Widely scattered showers/storms should increase in coverage this afternoon near a frontal zone and instability axis at KSBN. Brief restrictions will be possible if any stronger showers/storms track over the terminal. VFR with somewhat gusty southery winds this afternoon otherwise. Conditions deteriorate (MVFR-IFR) and rain (embedded thunder) coverage increases into tonight and Sunday morning in response to a deepening low pressure lifting northeast through northern IN and lower MI. Leading line could bring some stronger gusts to KFWA at some point this evening or the early overnight, with a quick transition to steady deformation rain on Sunday. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...None. OH...None. MI...None. MARINE...Gale Warning from 8 AM to 11 PM EDT Sunday for LMZ043-046. && $$ UPDATE...Brown DISCUSSION...Skipper AVIATION...Steinwedel