Severe Storm Risk - Sioux Falls, SD

There is a Enhanced Severe Storm Risk for your location. Continue reading for today's outlook from the National Weather Service's Storm Prediction Center. -------------------- National Severe Storm Outlook THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL PLAINS AND MID MISSOURI VALLEY SUMMARY Severe thunderstorms are expected this afternoon into tonight across parts of the southern/central Plains to the Upper Midwest. Supercells with very large hail and strong tornadoes are possible initially this afternoon, before one or more bowing clusters leads to a greater threat for severe/damaging winds this evening. Synopsis 12Z soundings across the central and southern Plains reveal steep mid-level lapse rates (8.8 deg C per km at OUN, SGF, and TOP) atop returning low-level moisture (100 mb mean mixing ratios of 15.4 and 13.1 g/kg at OUN and FWD, respectively). An MCV, from overnight storms across the Plains, is progressing into northern IL/southern MN. 12Z DVN sounding sampled a corridor of 50 kt at the base of this MCV. Morning surface analysis reveals an intricate surface pattern across the High Plains/Plains, with multiple lows within the lee troughing that extends from eastern MT through the central High Plains, a pair of warm fronts, and a residual outflow boundary across NE. The deepest surface low is over the far southern CO/KS border vicinity, with a warm front extending east-northeastward, roughly along the 70 deg F isotherm. A dryline also extends southward from this low into far west TX. Another low is in place farther north over western NE. Another warm front, this one along a sharp gradient in low-level moisture, extends northeastward from this low into far southeast SD before arcing more eastward across far southern MN and continuing across from southern WI into central Lower MI. The aforementioned outflow also extends eastward from this low across central NE. All of these boundaries will likely influence the severe potential today, combining with an emerging upper trough and moderate to strong instability, to support an expansive and complex scenario today. Central Plains into the Upper Midwest Expectation is for the northern warm front mentioned in the synopsis to continue northward throughout the day while as cold front sweeps southeastward across SD and NE. Thunderstorm development is anticipated as the cold front interacts with the returning low-level moisture. Moderate to strong buoyancy (i.e. MLCAPE from 2000 to 3000 J/kg) will support robust thunderstorms from southeast SD through south-central NE, potentially as far south as central KS. This activity along the front will become linear quickly with damaging gusts as the primary risk. Some cell-in-line structures could support large to very large hail, particularity early in the convective cycle. Within this larger area of severe wind and hail potential, two areas appear to have a greater tornado threat. One is from northeast/east-central NE into far southeast SD. Here, the influence of a residual outflow boundary could support more discrete development ahead of the front. Any discrete development in the warm sector would likely be supercellular and capable of all hazards, including very large hail (over 2.5") and a strong tornado. The other area is where the convective line interacts with the warm front amid a strengthening low-level jet, likely far northern IA/far southern MN. Here, increased low-level shear coupled with augmentation from interaction with the front could result in significant severe gusts as well as lined-embedded QLCS tornadoes. Central High Plains Thunderstorm development still appears likely across northeastern CO this afternoon in a low-level upslope flow regime. This activity will likely become supercellular and capable of producing large to very large hail given the presence of steep mid-level lapse rates, strong deep-layer shear, and moderate instability. Just how far east/northeast (into central NE) thunderstorms remains strong is a question of timing. Earlier storms could interact with the front as it moves through NE, potential leading to persistence or reintensification. However, later timing would take these storms into central NE behind the cold front. Steep mid-level lapse rates in place could still support these storms for a few hours, but the overall intensity will likely gradually decrease. Southern WI into Lower MI An MCV is current progressing into northern IL/southern MN. Modest buoyancy and moderate deep-layer shear will support isolated elevated thunderstorms capable of small hail and locally strong wind gusts through early afternoon. This MCV is expected to continue northeastward into Lower MI, potentially interacting with a warm front moving north across the region this afternoon. 12Z DVN sounding sampled enhanced mid-level flow with this MCV, which could result in enough shear to support organized convection along and near the warm front later this afternoon/evening. Strong multicells and an isolated supercell or two could occur, with an attendant risk for damaging winds, hail, and perhaps a tornado. South-Central KS into the eastern TX Panhandle and western OK Some guidance continues to show at least isolated high-based convection developing by late afternoon across parts of north-central KS southward into the eastern TX Panhandle/western OK. Any thunderstorms which can be sustained would likely be supercellular and capable of all severe hazards, including large to very large hail and tornadoes. Increasing low-level shear after 00Z supports a conditional risk for a strong tornado. -- No changes to these areas from the earlier 13Z Outlook -- Southeast On the western periphery of a surface high centered over the western Atlantic, diurnally maximized thunderstorm development should focus from the southern Appalachians across GA and the interior/western FL Peninsula. Even though deep-layer shear will remain weak, a favorable thermodynamic environment with steepened low-level lapse rates should support strong to pulse-severe type convection capable of producing isolated wind damage/downbursts and perhaps marginally severe hail. Central and North Texas/ArkLaTex/Lower Mississippi Valley A fairly robust cap is expected to remain across the southern extent of the warm sector today, with minimal/nebulous large-scale ascent over the southern Plains. Still, some guidance suggests elevated thunderstorms may develop through peak afternoon heating across parts of northeast TX into the ArkLaTex/lower MS Valley in persistent low-level warm advection regime. If this occurs, then isolated severe hail and damaging winds would be possible given the strong MUCAPE forecast. Mid-Atlantic Mid-level ridging should build over the Mid-Atlantic through the afternoon, which should tend to suppress most convection. However, a weak mid-level perturbation noted in water vapor imagery this morning over OH may support isolated convective development this afternoon across parts of MD/PA and vicinity. The overall environment does not appear overly favorable for organized severe thunderstorms, but gusty winds could occur with any of the stronger cores that may develop.