000 FXUS63 KIND 281900 AFDIND Area Forecast Discussion National Weather Service Indianapolis IN 300 PM EDT Thu Mar 28 2024 .KEY MESSAGES... - Warmer on Friday - Rain chances return Friday Night through Wednesday; thunderstorms possible at times - Some uncertain potential for strong to severe storms early next week && .SHORT TERM (This evening through Friday)... Issued at 300 PM EDT Thu Mar 28 2024 Rest of Today... The Midwest and Great Lakes region is currently within a multi- phased mid to upper level trough, aiding in LLJ enhancement. This will have minimal impacts on the surface layer today, outside of a brief 3-4hr period of increased gusting, up to 25MPH. A lobe of vorticity on the southern edge of the upper wave is aiding in low level pressure depletion, resulting in a weak 800-700mb wave. This has increased mid level cloud cover over northern portions of central Indiana. This increase in cloud cover could have minor impacts on afternoon high temperatures, with these areas remaining in the low 50s, vs upper 50s elsewhere. Tonight and Tomorrow... The aforementioned shortwave will deepen slightly into the overnight, resulting in a slightly more elongated saturated layer and possible even a few isolated showers and sprinkles. This should be contained to along and north of I-70, but a few sprinkles could stray into the rest of central Indiana. This extended cloud cover should help limit diurnal cooling some, removing the freeze threat. Still temperates should bottom out in the upper 30s by tomorrow morning. Southerly flow returns late tomorrow morning, increasing low level warm air advection and eventually surface temperatures. This will push highs back into 60s. The LLJ should weaken enough to mitigate momentum transfer, keeping a modest sustained wind out of the SW at 8-12MPH . && .LONG TERM (Friday night through Thursday)... Issued at 300 PM EDT Thu Mar 28 2024 The long term period looks quite prototypically Spring-like and active, with warm temperatures and multiple opportunities for showers and thunderstorms through the weekend into early next week, including some uncertain potential for severe storms Monday into Tuesday. Broad quasizonal to weakly anticyclonic flow will be present across much of the country over the weekend into early next week ahead of a large upper level trough/closed low, which will slowly push across the country into the middle of next week. Mid and upper level flow ahead of this trough will be fairly stout and broadly west/southwesterly, with lee surface cyclogenesis along a baroclinic zone promoting sustained southerly flow and thus poleward heat/moisture transport within the broad warm sector south of the boundary. Subtle leading impulses rounding the periphery of the ridge will promote development of one or more weak surface lows Friday night into early Monday, requiring precipitation chances to varying degrees throughout. Model convective indices suggest occasional low thunderstorm chances will be required during this time frame, but the pattern suggests little chance for organized convection over the weekend. However, ensemble mean precipitable water values via DESI will range between about 0.75 to 1.25 inches, which is anywhere from 75th percentile to near climatological maximum, so hydrologic concerns will require monitoring. As we get into early next work week, a more substantial surface low is expected to develop ahead of the encroaching upper level trough, moving through the region Monday night into Tuesday. While not necessarily a classical/textbook severe weather pattern, substantial dynamic support in the form of 100-130KT upper level jet streak, a 50+KT 850 jet, and a broad, open warm sector with several days of thermodynamic transport into the region will present at least some severe weather threat, particularly if mesoscale ingredients and timing can align in a favorable fashion. This will require close monitoring in the coming days. CIPS analogs and experimental CSU machine learning guidance have been suggesting a severe threat for some time now, and outlined day 5-6 areas on SPC convective outlooks are quite reasonable per current model solutions and these additional guidance sources. Uncertainty remains high, of course, but we can begin messaging at least a low severe threat early next week, primarily late Monday into Monday night/early Tuesday. Temperatures throughout the long term will generally be above normal given the broad southerly flow, with the exception of a brief period mid weekend as the boundary sags south of the area. NBM has a solid handle on this and requires no major changes. && .AVIATION (18Z TAF Issuance)... Issued at 133 PM EDT Thu Mar 28 2024 Impacts: - Winds early this afternoon will gust to 16-20KT Discussion: VFR conditions to prevail through Friday afternoon. Rather weak surface high pressure currently aligned just to the south of central Indiana will continue to drift southeast of the region. The split upper trough prevailing over the eastern CONUS will allow an embedded northern wave amid a weak warm advection/overrunning set- up. Winds and clouds will increase over KLAF and KIND this afternoon and evening, with gusts to 20kts. Winds will diminish through sundown with 5-7KT sustained after 02Z this evening. Light, isolated showers are possible tonight at KLAF, but should be isolated enough to removed inclusion in the TAF. Winds tomorrow will back towards the south, sustained at 7-10kts. && .IND WATCHES/WARNINGS/ADVISORIES...None. && $$ SHORT TERM...Updike LONG TERM...Nield AVIATION...Updike