220 FXUS63 KIND 300419 AFDIND Area Forecast Discussion National Weather Service Indianapolis IN 1219 AM EDT Sun Jul 30 2023 .Forecast Update... Issued at 1219 AM EDT Sun Jul 30 2023 Pulled the small PoPs over Knox and Daviess counties based on radar trends. Otherwise, would not rule out some patchy fog developing overnight over mainly NW parts of central Indiana, where IR satellite was showing clear skies and despite light northerly winds, little dry advection was occurring. Temperatures should have no problem dropping to the lower 60s overnight based on the clear skies and lower 60s dew points. && .Short Term...(This evening through Sunday) Issued at 253 PM EDT Sat Jul 29 2023 A cold front continues to progress south through the forecast area this afternoon...and was now located around 19Z across our southern counties. North of the front...lingering stratocu was limiting sunshine and temp rises while hot and humid conditions continued over southern portions of central Indiana. Temps in the upper 70s and lower 80s were common across the northern counties while mid and upper 80s were present further south. The lower Wabash Valley was the only spot with temps in the low 90s and heat indices above 100 degrees. The threat for convection is low and within the short term...focused over the next several hours over far southern portions of central Indiana. Current mesoanalysis continues to show an abundance of inhibition and subsidence left in the wake of the MCS early this morning with a noted cap off the IND ACARS sounding between 850 and 700mb. The instability axis currently resides from central Missouri E/SE into the lower Ohio Valley and expect the convective cluster currently to the west of KSTL to ride along this axis into the evening. There remains a chance that the lower Wabash Valley will be clipped by this cluster and will hold onto a low threat for storms as a result into the evening. That being said...the bulk of the impacts with the storms will focus to the southwest of the forecast area through the evening. Will also maintain an isolated risk for showers and storms along the far southern parts of central Indiana as the frontal boundary will likely not clear that area for another few hours. For the rest of the forecast area...the stratocu over the northern counties will continue to slowly mix out through the rest of the afternoon with skies set to become mostly clear this evening as high pressure builds south. Northerly winds may sporadically gust into the early evening before dropping off. Some potential for patchy fog late tonight but the dewpoints will likely drop enough to keep fog from becoming widespread. That dewpoint drop will finally bring a respite from the recent few days of oppressive conditions through the remainder of the weekend. The zone for convective clusters to track will focus to our southwest with tranquil weather expected across central Indiana through Sunday. Expect a diurnal cu field by Sunday afternoon with continued northerly flow. Temps...lows will fall back into the 60s across the forecast area tonight...with potential for lower 60s over northern counties. Sunday will see seasonable temperatures and lower humidity levels as low level thermals support mid and upper 80s across the region. && .Long Term...(Sunday night through Saturday) Issued at 253 PM EDT Sat Jul 29 2023 The synoptic scale pattern which is expected to prevail through the long range can be described as increasingly amplified. Namely, a deepening trough over the northeast with an amplifying ridge over the intermountain west. Our placement relative to each will lead to predominately northwesterly flow aloft. Additionally, surface high pressure passing to our north should lead to northerly to northeasterly flow at the surface through at least Tuesday. Consequently, a cooler and drier continental air mass will seep in from Canada. Surface dew points could drop into the 50s and remain there for some time, which would be a much needed break from the oppressive heat we have seen. Moisture convergence across the central Plains is expected to lead to a band of instability located roughly along the northern edge of the western ridge (from South Dakota southeast into Missouri). Given the modest to at times fast flow northwesterly aloft, roughly parallel with the instability axis...should set the stage for a "ridge rider" convective regime. This pattern comes into alignment by early Monday, with most guidance showing multiple rounds of storms developing well to our west and propagating southeastward. The main axis of instability / anomalous moisture should remain west of our CWA through Wednesday, which will allow dry conditions to persist into Wednesday. Through the early part of the week, ensemble guidance generally shows the western ridge slowly building eastward. By Wednesday morning the ridge is modeled to be centered roughly over Oklahoma. This gradual eastward motion in turn allows the instability axis to approach Indiana. Most deterministic guidance has increasing precipitation chances beginning Wednesday, and continuing into Friday. A more pronounced trough may pass to our north Thursday into Friday, dragging a cold front through the region. Consequently, a more widespread round of organized convection is possible Thursday or Friday. While organized convection is possible at times beginning on Wednesday, refining details at this range is difficult. Coverage and timing will largely be determined by mesoscale features not currently resolvable by the global models / ensembles. Here, pattern recognition is key...and the pattern supports a few rounds of convection and perhaps an MCS or two later in the week. Whether this sets up to our west or closer to Indiana will come into greater clarity as the week progresses. Looking at non-convective weather, winds, temps, etc...dry continental air will be present at the beginning of the week, as mentioned earlier. Relatively light north to northeasterly winds should veer and gain a southerly component as the surface high slides eastward. This allows temps to gradually moderate, warming slightly as the ridge builds in. No heat like recent days is expected, with highs only in the mid to upper 80s. Dew points will likewise recover, climbing back into the 60s/near 70. && .Aviation...(06Z TAF Issuance) Issued at 1159 PM EDT Sat Jul 29 2023 Impacts: - MVFR fog possible at the smaller airports toward 09z and through 13z, otherwise high confidence in VFR flying conditions with just passing cirrus Discussion: Could see some MVFR and briefly worse fog at the smaller airports overnight, otherwise high pressure and a dry column will lead to VFR flying conditions with just passing cirrus with impulses in NW flow aloft. Winds will be most NW and N up to 10 knots but very light to calm at the smaller airports overnight. && .IND WATCHES/WARNINGS/ADVISORIES... None. && $$ Update...MK Short Term...Ryan Long Term...Eckhoff Aviation...MK