925 FXUS63 KIND 100108 AFDIND Area Forecast Discussion National Weather Service Indianapolis IN 908 PM EDT Mon Jun 9 2025 .KEY MESSAGES... - Isolated showers and thunderstorms this afternoon, mainly north - Dry with warming trend mid-week, increasing humidity - Precipitation chances return late week into the weekend && .FORECAST UPDATE... Issued at 908 PM EDT Mon Jun 9 2025 Quiet and cool night ahead. Surface analysis late this evening shows a cold front extending from SE MI across Indiana to southern IL and Central MO. GOES16 shows CU and AC near the front diminishing in coverage as heating is lost and the front slides eastward. Radar shows no returns and dew points were in the 50s. Further southwest, high pressure was found over OK and KS. Aloft, water vapor showed subsidence in play over Indiana and points to the southwest while a large and broad upper low was found over the Great Lakes. Overall, ongoing forecast remains in good shape. Decreasing cloudiness is expected to continue as clouds to continue diminish and the cold front slides eastward. Subsidence from the southwest will also continue to build eastward along with e approaching high pressure system. Thus skies becoming mostly clear overnight appears like a good forecast. Given our dew point temps in the mid 50s, ongoing lows in the mid to lower 50s appear on the mark. Overall, no significant changes to the ongoing forecast. && .SHORT TERM (This evening through Tuesday)... Issued at 254 PM EDT Mon Jun 9 2025 Synoptic analysis reveals a large stacked low located over northern Wisconsin. A cold front extends south out of the Great Lakes stretching from lower Michigan through southern Indiana. This front is what brought rain and storms earlier this morning. Analysis also reveals a secondary front over northern Illinois, which is moving southeastward towards Indiana. Clearing skies ahead of the secondary front will allow for very steep low-level lapse rates to develop by afternoon. Lapse rates from 0 to 3 km may reach 9.0 to 9.5 C/Km which is absolutely unstable. However, above 3km there is a substantial warm nose with poor lapse rates. This will limit convective instability to a very shallow region near the top of the boundary layer. While it is possible that some showers develop along the advancing front...it is becoming increasingly unlikely that any achieve heights tall enough to generate thunder. Better thermal profiles exist with northward extent, so some isolated instances of thunder cannot be ruled out across our north. In terms of convective hazards, we are not expecting anything in terms of severe weather. Though, given the very steep low-level lapse rates and relatively dry PBL air...a few isolated wind gusts to 40mph are possible within the strongest showers/storms. Otherwise, expect temperatures to rebound nicely into the mid to upper 70s today with a few locations reaching 80. Temperatures decrease overnight after the frontal passage with lows dipping into the low to mid 50s. && .LONG TERM (Tuesday night through Monday)... Issued at 254 PM EDT Mon Jun 9 2025 Ensemble guidance depicts a split flow upper-level pattern persisting through much of the week, with the polar jet straggling the US Canadian border. Surface high pressure is modeled to reside over the western Atlantic, with a thermal low developing over the Intermountain West. This should promote a broad but light southerly flow. As such, guidance is in good agreement on a warming trend along with increasing humidity this week. Ensemble 850mb temps rising to between 16-18C corresponds to temperatures in the mid 80s. Dew points on Wednesday may be quite comfortable as a pocket of dry mid-level air moves in aloft, which could be mixed downward during the afternoon hours. Higher dew points begin to advect northward on Thursday, which should allow most locations to see values in the 60s to 70 at times. Relatively quiet weather is expected for the next few days, but that may change by this weekend. Guidance is hinting at a few slow-moving upper waves passing by which could provide enough forcing for showers or storms. With the jet stream to our north, flow through the column appears to be rather light. So while instability may be robust upwards of 2000-3000 J/Kg at times, shear looks to be minimal. Any showers or storms this weekend may be of the pulse variety or perhaps loosely organized clusters. Given the weak forcing at hand, activity may be dependent on outflow boundaries and cold pools left by previous convection. Therefore, forecast uncertainty is higher than normal in terms of convective coverage and timing. && .AVIATION (00Z TAF Issuance)... Issued at 610 PM EDT Mon Jun 9 2025 Impacts: - VFR Conditions expected. - BKN VFR CU possible on Tuesday Discussion: A cold front was pushing across Central Indiana late this afternoon. GOES16 shows CU and AC with this feature pushing across the TAF sites. As heating is lost this evening and as the front progresses east, decreasing cloudiness with unlimited cigs are expected by late this evening. This will persist through mid morning Tuesday as high pressure builds across the Ohio Valley from the west. Forecast soundings on Tuesday show saturation near 5K ft as convective temperatures are reached during the afternoon hours. An inversion above this level will prevent deep CU growth and high pressure and subsidence aloft will remain in play. Thus VFR conditions through the TAF period. && .IND WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...Puma SHORT TERM...Eckhoff LONG TERM...Eckhoff AVIATION...Puma