934 FXUS63 KIND 161900 AFDIND Area Forecast Discussion National Weather Service Indianapolis IN 300 PM EDT Wed Apr 16 2025 .KEY MESSAGES... - Increasing clouds tonight, patchy frost possible northeast of Indianapolis - Rain showers with perhaps a rumble of thunder on Thursday - Warming trend towards the end of the week with strong to severe Thunderstorms possible late Friday - Multiple rounds of rain Friday night through this weekend with the potential for returned river flooding && .SHORT TERM (This evening through Thursday)... Issued at 259 PM EDT Wed Apr 16 2025 Troughing is currently taking hold over the West Coast with ridging working its way into the Great Plains. Surface high pressure is currently passing through the Midwest, and will slide eastward reaching the East Coast tomorrow. Surface winds here in Indiana are currently out of the northwest, but should go calm overnight as the high passes by. Once its to our east, expect winds to increase again and become southeasterly. With calm wind conditions overnight, lows may dip into the upper 30s in rural areas. Some patchy frost is possible, mainly northeast of Indy. Increasing high clouds could lessen radiational cooling potential somewhat. Low pressure taking shape in the lee of the Rockies, associated with the deepening trough, will allow for a warm front to lift northeastward out of Missouri overnight. This front approaches Indiana tomorrow morning with advection-driven showers at times ahead of its arrival. Some elevated convective elements are possible as well, but profiles do not support robust elevated convection at this time. A rumble of thunder is still possible, however. Confidence regarding high temperatures on Thursday is a bit lower than normal, since coverage of rain showers and timing of the warm front are not yet pinned down. Greater coverage of showers and a slower front could allow temps to be lower than currently shown. && .LONG TERM (Thursday night through Wednesday)... Issued at 259 PM EDT Wed Apr 16 2025 Thursday night and Friday... Anomalously warm conditions are expected early in the extended as south/southwesterly flow strengthens ahead of an approaching low pressure system. Look for lows near the mid 50s Thursday night with highs in the upper 70s to near 80F on Friday. The pressure gradient strengthening will also favor increasingly windy conditions, especially during the day Friday as diurnal mixing into a strong LLJ helps transfer stronger gusts to the surface. Wind gusts around 30- 40 mph appear likely. Precipitation is not expected Thursday night as a warm front continues to lift north of central Indiana with little to no forcing in place. Guidance then shows a strong EML developing on Friday which is likely going to limit the potential for convection through the day. Friday night through early next week... The low pressure system moves in late Friday promoting widespread precipitation and the potential for severe weather. Persistent strong S/SW flow will aid in sufficient destabilization. Aloft, increasing mid-upper level winds as the parent trough approaches will provide favorable deep-layer shear for organized thunderstorms. Some of these storms could be severe with the primary threats being damaging wind gusts and large hail. The question that remains is how long will it take for increasing lift and warm-moist advection to erode the EML. Most guidance suggest this occurs during the evening though a few models hold off convection until later in the overnight period. There is increasing confidence in a flooding threat over the weekend. An upper ridge remaining anchored off the southeast coast along with broad troughing over the central CONUS will continue to pump anomalous moisture towards the area. This along with a frontal boundary expected to stall across the region late Friday into Saturday supports the threat for subsequent rounds of convection. Guidance suggest the potential for 1-3 inches of rain with locally higher amounts possible due to convective elements. Expect an elevated flash flooding threat along with renewed minor flooding for portions of the main stem rivers. Rain chances finally begin to taper off on Monday as the stalled front shifts eastward. Dry conditions are expected to return Monday night into Tuesday before another system approaches towards midweek. Temperatures remain near normal over the weekend into early next week before warming up. && .AVIATION (18Z TAF Issuance)... Issued at 139 PM EDT Wed Apr 16 2025 Impacts: - Rain showers possible after 14z Thursday. Low chance thunder. - Wind gusts to 25kt possible Thursday afternoon. Discussion: VFR conditions expected through the TAF period. Clouds increase overnight as a warm front approaches from the west. Ceilings lower with time but expected to remain VFR. Some rain showers are possible after about 14z, and guidance has been trending a bit more aggressively with this in recent cycles. Will introduce VCSH with this TAF update. There is also a low chance of thunder as well, but less model support exists for it compared to just rain. Winds out of the NNW today should gradually die down, potentially going light and variable tonight, before switching to southeasterly on Thursday morning. Wind gusts between 20 and 25 knots are possible Thursday afternoon. && .IND WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...Eckhoff LONG TERM...Melo AVIATION...Eckhoff