085 FXUS63 KIND 081756 AFDIND Area Forecast Discussion National Weather Service Indianapolis IN 156 PM EDT Thu Jul 8 2021 ...Updated Aviation Discussion... .Forecast Update... Issued at 1000 AM EDT Thu Jul 8 2021 Scattered showers and isolated thunderstorms across mainly northern counties this morning...will continue to slide eastward...while overall convective coverage slowly expands and builds southward through this afternoon. While current storms are more garden- variety in nature, a marginal risk for strong/severe winds continues for this afternoon and at least early into this evening for most of the CWA. Threat of heavy rainfall and very localized flooding is also present under stronger storms through this evening. Considerable cloudiness will keep temps from rebounding farther than the low to mid 80s for most locations amid the high humidity. && .Short Term...(Today through Friday) Issued at 301 AM EDT Thu Jul 8 2021 Scattered convection was across mainly the far northern forecast area, stretching back into central Illinois early this morning. Isolated convection was across the far southwestern forecast area. A surface cold front extended from lower Michigan southwest to north of St. Louis. An upper trough was just west of the area. Based on recent trends, believe that at least isolated convection will continue through the remainder of the predawn hours, especially with the upper trough and front nearby. Will continue some PoPs before 12Z. After 12Z, the left exit region of an upper jet will be near the northern forecast area. This will likely aid in the production of some convection by mid to late morning there. Later during the day, as the cold front moves through the area, it will interact with unstable air to produce scattered to numerous showers and thunderstorms. Overall, will end up going at least likely PoPs most areas at some point during the day. There is enough shear around to perhaps get some isolated severe storms this afternoon, mainly across the eastern and southern forecast area ahead of the front. The front will be exiting the area this evening, so will just keep some low PoPs in the east during the evening hours. Surface high pressure will build into the area overnight into Friday morning, and this will provide dry and cooler conditions. During the afternoon, an upper disturbance in northwest flow aloft will approach the area. Some lift will occur aloft with this feature by late afternoon. However, the surface high will still have influence over much of central Indiana, keeping the low levels dry. Thus, while some sprinkles may be possible in the far west later on Friday, feel that mentioning PoPs will be overdone. Will go with a dry forecast. && .Long Term...(Friday night through Wednesday) Issued at 301 AM EDT Thu Jul 8 2021 The long term period looks to be active, beginning with the arrival of leading shortwave impulses ahead of a strengthening low early in the weekend. This low will close off somewhere in the region, likely to our west per the general consensus of deterministic guidance, and lead to multiple potential rounds of showers and thunderstorms throughout the long term period. While a marginal severe threat would not be out of the question given at times modest deep layer shear values, the more substantial concern will be hydrologic with deeply saturated/pseudotropical profiles (featuring deep but thin instability profiles) and precipitable water values continuing to be advertised at 1.8 to 2 inches, which approaches climatological maximum for the time of year. This, along with wet antecedent conditions means heavy rain from thunderstorms, particularly if occurring in multiple rounds, will have little trouble causing at least nuisance flooding issues, if not flash flooding and renewed river flooding. OHRFC river flood ensembles indicate at least a 30 percent chance of renewed minor flooding along portions of the main stem rivers, particularly in southwest Indiana where river flooding has been an issue for some time now, and just recently ended. The closed upper low looks to lift out of the area by mid week next week, although additional disturbances in the weakly cyclonic flow will continue to merit precip chances through the end of the period. Given the overall pattern, temperatures should be at least a bit below normal, particularly early in the long term period, and the blend has handled this quite well. && .Aviation...(18Z TAF Issuance) Issued at 155 PM EDT Thu Jul 8 2021 IMPACTS: - Scattered convection this afternoon will continue into early evening, with IFR/MVFR and gusts over 25kt in convection - Sustained winds generally 10kt or less...except in/around storms - Gradual wind shift to northwest this evening DISCUSSION: Scattered convection currently along the I-70 corridor, with isolated strong/severe winds...will expand in coverage through this afternoon and early evening along and south of the I-70 corridor. MVFR ceilings at KIND/KLAF should lift to VFR at KIND late this afternoon, and KLAF early this evening. Otherwise VFR is expected to prevail through Friday afternoon...except in and around today's showers/storms where brief IFR/MVFR is expected. Winds near stronger cells may gust as high as 25-40 kts although low confidence any site sees winds this intense. Showers/storms will end from north to south this evening as the associated cold front continues to slowly cross the region. Winds will veer to northwesterly early this evening...and then remain generally under 10 kts the remainder of the TAF period. && .IND WATCHES/WARNINGS/ADVISORIES... None. && $$ Update...AGM Short Term...50 Long Term...Nield Aviation...AGM