542 FXUS63 KIND 122355 AFDIND Area Forecast Discussion National Weather Service Indianapolis IN 755 PM EDT Thu Jun 12 2025 .KEY MESSAGES... - Numerous showers and thunderstorms Friday through much of the weekend - Heavy downpours and localized flooding will be the primary threat Friday afternoon through Saturday evening - A near daily risk for scattered showers and storms will continue through much of next week - Muggy conditions are expected through the upcoming week && .SHORT TERM (This Evening through Friday)... Issued at 246 PM EDT Thu Jun 12 2025 Cirrus expanding over the region early this afternoon in an increasingly thicker shield with scattered diurnal underneath the higher deck. 18Z temperatures were into the low and mid 80s with a noticeable uptick in humidity levels as dewpoints were largely in the 60s. The upper low poised to bring another round of stormy and unsettled weather to central Indiana is lifting northeast out of the southern Plains this afternoon and will move into the mid Mississippi Valley by Friday evening. With a frontal boundary meandering over the region as well...anticipate scattered to numerous areas of convection developing for Friday. The rest of the afternoon and evening will remain quiet with remnant dry air and lingering ridging aloft over the region. Mid and high level clouds will continue to expand into the forecast area from the southwest with a plume of Gulf moisture arriving overnight ahead of the upper low. Cannot rule out a few showers after midnight but in the absence of more notable lift expect most of the area remains dry until near daybreak Friday. Much deeper moisture overspreads the region on Friday with isentropic lift increasing as well. Greater coverage of showers will be in the Wabash Valley near daybreak then expand northeast through the morning. Instability will be limited by the clouds and increasing convection but still think CAPEs will peak near 1000j/kg in the afternoon. A few stronger cells are possible with gusty winds as cores collapse but poor lapse rates and little available BL shear will keep convection disorganized into the evening. PWATS will rise to 1.75 inches or greater in the afternoon with brief torrential downpours as the primary impact from showers and storms. Could easily see a couple inches of rain in spots with a localized flooding threat and this will continue into Saturday as well. Temps...lows tonight will hold near 70 degrees with the deeper moisture advection into the Ohio Valley. Highs should rise into the lower 80s over most of the forecast area on Friday even with the clouds and convection. && .LONG TERM (Friday Night through Thursday)... Issued at 246 PM EDT Thu Jun 12 2025 Split flow aloft will persist through the weekend with the jet stream well to the north close to the Canadian border. The combination of an upper low moving slowly through the Ohio Valley with a stagnant frontal boundary and weak surface wave riding along it will keep an unsettled and stormy pattern for much of the weekend. A strong upper level ridge will build into the southern Plains by the middle of next week and place the Ohio Valley and lower Great Lakes on its periphery and within a favored zone for increased impacts for convective clusters lasting potentially through next weekend and beyond in a very warm and unstable environment. Friday Night through Sunday The combination of a nearly stationary boundary and arrival of the aforementioned upper low will maintain periodic showers and thunderstorms into the weekend. The lack of substantial BL shear will result in a messy...multicellular convective mode dependent on instability focused especially through Saturday evening. Forecast soundings support the threat for heavy rain with PWATs increasing to near 2 inches resulting in a localized flood threat for areas getting repeated rounds of convection.. Mesoscale features and boundaries will serve as a primary impact where repeated areas of convection align while also aiding in scattered stronger pulse intensity convection in the absence of more substantial shear needed for organized severe weather. Gusty winds and small hail will be possible with any stronger cells as cores collapse. Model guidance continues to hint at potential for a lower convective risk Sunday as the boundary shifts to near or just south of the Ohio River with high pressure across the Great Lakes. The front remains in close enough proximity though to warrant a continued mention of precip chances focused especially across the southeastern half of the forecast area. Humidity levels will rise noticeably with oppressive Tds peaking in the lower 70s at times over the weekend with a muggy feel to the air. Highs will largely remain in the upper 70s and lower 80s through the weekend with the increase clouds and convection. Sunday Night through Thursday The remnant frontal boundary will remain over the region early next week with renewed potential for scattered convection as wave aloft ripple across the Ohio Valley. Eventually the upper level pattern will transition as broad ridging aloft expands into he southern Plains by the middle of next week. This will place the region onto the periphery of the ridge and in the primary zone for strong convective clusters to ride up and over the ridge from the northern Plains southeast into the Ohio Valley. It remains far too early to employ any detail into the development of this pattern...but confidence is growing in an increased threat for convective impacts for much of next week and through next weekend within a moist and unstable environment. Highs will rise into the mid and upper 80s with muggy conditions persisting. && .AVIATION (00Z TAF Issuance)... Issued at 745 PM EDT Thu Jun 12 2025 Impacts: - MVFR conditions developing within showers/storms Friday morning and persisting throughout the TAF period Discussion: VFR conditions will continue for the rest of the evening and through tonight as high level cloud coverage steadily increases from the southwest. Radar imagery already shows a precipitation trying to work in aloft from the southwest, but due to such a dry atmospheric profile, nothing is reaching the ground or impacting surface conditions. Cigs will steadily lower through the night, but likely will not drop to MVFR levels until Friday afternoon. Showers increase from the southwest late tonight, with showers and thunderstorms near all TAF sites within the 13-17z timeframe. Convection will likely be at max coverage during the afternoon and evening hours. Still expecting some showers and storms tomorrow night, however coverage may be more isolated to scattered. Expect MVFR or lower cigs and vis under heavier showers and storms throughout tomorrow. Winds remain out of the south less than 10 kts through the period. Winds may become more southeasterly by tomorrow evening. && .IND WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...Ryan LONG TERM...Ryan AVIATION...CM