824 FXUS63 KIND 180657 AFDIND Area Forecast Discussion National Weather Service Indianapolis IN 257 AM EDT Sat Oct 18 2025 .KEY MESSAGES... - Showers and thunderstorms developing this afternoon then becoming widespread this evening and tonight with locally heavy rainfall - A few strong to severe storms possible this afternoon and tonight with damaging winds as the primary threat - Cooler with rain and wind gusts peaking at 35 to 40 mph Sunday - Seasonably cool temperatures for the first half of next week && .SHORT TERM (Today and Tonight)... Issued at 257 AM EDT Sat Oct 18 2025 Relatively dense cirrus shifting east across the region early this morning as a subtle wave aloft traverses the back side of the upper ridge. A steady S/SE wind continues at near 10mph for many locations with temperatures ranging from the mid 50s to lower 60s at 06Z. After a largely uneventful Fall to this point with an extended period of warm and dry conditions...the next 24 to 48 hours will signal the initial shift to a more unsettled and typical mid Autumn pattern highlighted by a much more amplified flow aloft and stronger surface lows tracking through the region every 3-5 days with greater variability in temperatures and overall weather. A frontal boundary will drift east into the area through the course of the day with an increasing threat for scattered convection by this afternoon. As a strong upper low moves across the Canadian prairies...an amplifying trough will develop across the central Plains with phasing jet energy initiating surface cyclogenesis along the boundary by this evening across the Mid Mississippi Valley. The low will deepen as it lifts across the region tonight with widespread rain...scattered strong convection and windy conditions. The rain and wind will last into Sunday as much cooler air arrives behind the cold frontal passage. The back edge of the cirrus that has been over the region since Friday afternoon will depart to the east over the next few hours with skies starting out mainly clear for much of the forecast area this morning. A broken line of convection along the frontal boundary from eastern Kansas into northwest Illinois will progress to the northeast through daybreak. Mid level clouds associated with the front will expand back into the northwest half of the forecast area by late morning with an increasing potential for scattered convection to develop along it across central and eastern Illinois by early afternoon. The sunshine this morning combined with broad warm advection... increasing low level moisture and southwest winds that will become gusty quickly will all contribute to an unstable environment with CAPE values rising to around 1000 j/kg by around 18Z. Convection over Illinois will lift northeast into the Wabash Valley and become better organized as they expand across much of the northwest half of central Indiana through late day. Potential exists for a few of these storms to be strong to locally severe with gusty winds as the primary threat due to a predominantly unidirectional wind profile. Further southeast across central Indiana any convection should largely remain isolated with the bulk of the rain holding off until this evening. Wind gusts peaking at 25 to 30mph later today will drop back this evening into the early overnight before increasing substantially as the cold front passes predawn Sunday. Showers will become widespread into the evening focused again over the northwest half of the forecast area along the remnant boundary as low pressure begins to organize across the mid Mississippi Valley. May even see the area of precipitation pivot to the northwest before expanding back east as the surface wave moves into the region. While CAPE values will diminish through the evening... weak instability will linger as a narrow...low topped convective line develops ahead of the deepening low pressure and cold front and moves across the region after midnight. The more intense portion of the line will be south of the Ohio River and particularly from the Tennessee Valley south where instability will be more plentiful. That being said...plenty of BL shear will be present with a 60+kt low level jet to support a shallow...fast moving QLCS across the region in the 04-08Z timeframe that will have a risk to pull strong winds briefly to the surface and carry a nonzero risk for a couple brief spinups especially for areas near and south of I-70. Steadier wind whipped rain will follow the line through and beyond daybreak Sunday. Trends continue to support widespread rainfall from 1 to 2 inches across central Indiana through Sunday with the highest amounts focused over the northern Wabash Valley. While localized nuisance flooding is possible from brief periods with intense rainfall rates...the overall dry ground conditions will mitigate any broader flooding concerns. Temps...nudged highs back slightly from the model blend but should still see highs in the upper 70s and lower 80s across the forecast area. Lows tonight will be dependent on the speed of the cold frontal passage predawn Sunday with noticeably cooler air in its wake. Expect temperatures falling back to the low to mid 50s from west to east by daybreak Sunday with the potential to fall further through Sunday morning as cold advection establishes. && .LONG TERM (Sunday through Friday)... Issued at 257 AM EDT Sat Oct 18 2025 Sunday... Widespread precipitation will likely be ongoing at the start of the period as a deepening low pressure system moves through with abundant moisture still in place. This rainfall is much needed and should help to at least slightly improve drought conditions. Expect the low pressure system to shift east during the afternoon/evening allowing precipitation to taper off from west to east as drier air filters in. A tight MSLP gradient along with shallow mixing into a strong LLJ will promote windy conditions. Wind gusts around 25-35 mph are likely with occasional gusts as high as 40 mph. Sunday night through Monday... Quiet weather is expected during this period with upper ridging and surface pressure over the region. Cold air advection behind the departing system will keep temperatures near or slightly below normal. Look for winds to weaken Sunday night due to a relaxing pressure gradient. Models depict the pressure gradient tightening up again on Monday as another system quickly approaches. This will promote breezy conditions with gusts up to 30 mph possible. Monday night onward... Marginal moisture return ahead of a system moving through Monday night will limit rain chances to around 20 to 40 percent and should keep any rainfall amounts light. An associated cold front will provide another shot of cooler and drier air, keeping temperatures slightly below normal. Quiet weather returns Tuesday and Wednesday before another upper level impulse moves in late next week. Uncertainty increases towards the end of next week as model solutions diverge. At least subtle forcing from the upper wave and moisture beginning to return north supports low rain chances. && .AVIATION (06Z TAF Issuance)... Issued at 104 AM EDT Sat Oct 18 2025 Impacts: - Wind gusts up to 25kts mid morning through the afternoon - Scattered convection developing mid to late afternoon, more widespread rain this evening into the overnight - Deteriorating ceilings and visibilities by late evening Discussion: Thicker cirrus drifting across the region early this morning as an upper wave passes through. Skies will briefly clear during the predawn hours through daybreak before mid level clouds increase from the west through the morning ahead of an approaching frontal boundary. Winds will become gusty rather quickly this morning... peaking around 25kts from late morning into the afternoon. Progressively deeper moisture will advect into the Ohio Valley during the afternoon with scattered convection developing after 18Z. Rain and embedded convection will become widespread by the evening as low pressure strengthens over the lower Ohio Valley. There is potential for a brief 2-3 hour break in rain at KBMG and KIND as the low organizes before rain expands back east late tonight. Southerly winds will drop off this evening then increase in the predawn hours Sunday as the cold front sweeps across the region. Ceilings will drop to MVFR late evening into the overnight with IFR conditions likely prior to daybreak Sunday. && .IND WATCHES/WARNINGS/ADVISORIES...None. && $$ SHORT TERM...Ryan LONG TERM...Melo AVIATION...Ryan