Area Forecast Discussion
Issued by NWS Indianapolis, IN
Issued by NWS Indianapolis, IN
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467 FXUS63 KIND 240524 AFDIND Area Forecast Discussion National Weather Service Indianapolis IN 124 AM EDT Tue Sep 24 2024 .KEY MESSAGES... - Widespread showers and a few thunderstorms through Tuesday - Sneaky potential for a few severe storms Tuesday afternoon into the early evening - Seasonable temperatures for much of this week with highs in the 70s and lower 80s and lows in the 50s and 60s - Potential for more rain late week into the weekend from tropical remnants && .FORECAST UPDATE... Issued at 941 PM EDT Mon Sep 23 2024 Some widely scattered showers continued across central Indiana this evening. The next round of forcing/rain is already into central Illinois, and this will push east into the area in a few hours. Adjusted PoPs to reflect the above, with most areas still having high PoPs at some point. Given the available moisture, brief heavy rain remains possible. Temperatures won`t change much with the rain moving through at times, so just made some tweaks to low temperatures based on latest trends. && .SHORT TERM (This Evening through Tuesday Night)... Issued at 305 PM EDT Mon Sep 23 2024 Low stratus has been prevalent across central Indiana so far today with a cool low level flow largely out of the northeast. A broad area of rain continues its northeast expansion across the forecast area this afternoon. Temperatures at 18Z ranged from the upper 60s to the mid 70s. The unsettled pattern that commenced on Sunday will persist through Tuesday evening with additional opportunities for rain and storms. The cold front that passed through the area Sunday evening now resides near the Ohio River. The boundary will shift north back into the forecast area tonight and Tuesday with a series of surface waves traversing it. The final surface low will track through the region Tuesday afternoon and evening...and presents a sneaky scenario for isolated to scattered severe storms. Will discuss this in greater detail below. Rest of This Afternoon through Tonight The area of rain draped across the southwest half of the forecast area currently will continue press northeast...likely diminishing in coverage slightly as it interacts with drier air above the boundary layer inversion. There remains very weak instability aloft and have seen periodic lightning strikes but for the most part...the bulk of the storms should remain south of the boundary in Kentucky where instability is greater. The showers will continue into the evening with a gradual increase in coverage developing near or just after sunset as 850mb winds increase and nose into the region from the southwest. Model soundings support a bump in instability as well that will likely tend towards increased convection later this evening into the overnight as the low level jet strengthens further. There is solid potential to see a half inch to inch for much of the region with locally higher amounts by Tuesday morning. These amounts alone should not create any flood issues but will provide additional relief from the ongoing drought conditions. Tuesday and Tuesday Night There may be a brief lull in convection Tuesday morning into the early afternoon as the overnight convection shifts northeast with the remnant boundary lifting north as a warm front. The focus will shift to another round of scattered to numerous showers and storms Tuesday afternoon and early evening as the main surface wave moves into the area with some potential for a few severe storms. The overall pattern on Tuesday is chaotic and messy as the combination of saturated conditions within the boundary layer and the early day convection leads to more questions regarding how much destabilization can take place as storms fire in the vicinity of the surface low Tuesday afternoon. That being said...there are parameters in play that suggest a sneaky scenario for scattered severe storms during the afternoon and early evening. The track of the surface low and position of the warm front out ahead of the wave will be key pieces in where this potential will best align...but plenty of directional shear within the moist near surface layer will exist and this shows up nicely in the hodographs up to 1-2km. Add in the strong likelihood that LCLs will be generally under 2kft and 0- 3km CAPE values that will likely be near if not exceed 100 j/kg and there is support for some mischief from showers and storms as the low passes through in the form of either damaging winds and/or a weak tornado threat. Afternoon and early evening would likely be the primary timeframe for these concerns on Tuesday. The low will move away to the northeast Tuesday evening with a frontal boundary sweeping through the area. Drier air will advect in behind the front but the lingering deep moisture within the boundary layer will keep skies mostly cloudy all night Tuesday. Temps...lows tonight will drop into the lower and mid 60s across the forecast area. Expect another cooler day Tuesday with an abundance of clouds and the scattered to numerous areas of convection. Low level thermals support temperatures remaining in the 70s. Temps will fall back into the mid and upper 50s behind the cold front Tuesday night. && .LONG TERM (Wednesday through Monday)... Issued at 305 PM EDT Mon Sep 23 2024 The long term period will have numerous chances for showers and thunderstorms after a brief break in the rain to start off the period. Recent model runs, as well as the National Hurricane Center, are leaning towards hurricane remnants reaching Central Indiana late this week. Solutions are showing that the remnants may take on a Fujiwara effect, interacting with an upper low that broke off of the system bringing rain to the area today and tomorrow, which could help to draw the remnants to our area. Confidence is still not very high as solutions still aren`t quite in sync but they are starting to agree better than before. Therefore, PoPs will be spread across numerous days beginning early Thursday morning and lasting through the end of the forecast period. Winds will be increasing Friday on the leading edge of the remnants with non-thunderstorm gusts potentially getting to 35-40 mph. When the center of the remnants reaches the Ohio Valley, there is a potential for brief spin ups to form as is somewhat common in these scenarios. Temperatures will be more seasonable through the long term with highs from the mid-70s to low 80s. && .AVIATION (06Z TAF Issuance)... Issued at 124 AM EDT Tue Sep 24 2024 Impacts: - MVFR or worse conditions through the night into early afternoon Tuesday, with periods of IFR - Periods of showers and perhaps a few thunderstorms the night into Tuesday Discussion: Ceilings vary from high end MVFR to IFR at this time, and expect conditions to deteriorate through the night with a period of IFR likely at all sites late tonight into Tuesday morning, before gradual improvement through the day. VFR conditions will likely return by late afternoon or evening at all sites. Showers can be expected at times, with some thunderstorms possible, though odds are far too low for anything beyond a vicinity mention at HUF/BMG early in the period as a cluster of storms moves nearby in the first few hours. Visibilities will be restricted at times both in showers and fog, primarily through the night. VFR conditions should return to all sites during the late afternoon or evening hours at the latest tonight. Winds will be around 10KT or less throughout the period, variable at times overnight but generally veering from easterly to westerly as low pressure passes through the area. && .IND WATCHES/WARNINGS/ADVISORIES...None. && $$ UPDATE...50 SHORT TERM...Ryan LONG TERM...KF AVIATION...Nield