Severe Storm Risk - Sioux Center, IA

There is a Marginal 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 A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM PORTIONS OF THE OHIO VALLEY INTO SOUTHERN MID-ATLANTIC AND CAROLINAS SUMMARY Severe thunderstorms capable of mainly damaging gusts are possible across portions of the Ohio Valley into southern Mid-Atlantic and Carolinas this afternoon and evening. Isolated occurrences of large hail and severe wind gusts also appear possible over parts of the northern and central Plains today into tonight. Ohio Valley into the Carolinas An MCS continues to progress southeastward towards the central Appalachians this morning. The outflow has surged well ahead of the deep convection along the western edge of this MCS, but remains much closer to the two primary cores of deep convection along the central and eastern portions of the MCS. General expectation is for this MCS to continue southeastward across the central Appalachians and into the Mid-Atlantic, while the westward-progressing outflow stalls and loses definition. Currently, the airmass downstream across the Mid-Atlantic is characterized by dewpoints ranging from the upper 60s across northern VA into the mid 70s across southeast NC/eastern SC. Strong heating is anticipated across much of this region today, with high temperatures ranging from the low 90s over northern to the upper 90s/low 100s across central/eastern SC. These warm and moist surface conditions will support moderate to strong afternoon buoyancy, despite poor mid-level lapse rates. Reintensification and/or renewed thunderstorm development is expected as the MCS (and associated vorticity maximum) interacts with this destabilized airmass. This region will be along the southerly periphery of a belt of mid-level northwesterlies, and the resulting vertical shear could help maintain a favorable cold pool/updraft balance needed to maintenance of a progressive convective line. Guidance varies on whether one coherent convective line or a series of smaller bowing segments will develop, but either case would yield a threat for damaging gusts. Highest probability for damaging gusts is expected across eastern NC where the best overlap between buoyancy and vertical is expected. Additional afternoon development is expected farther west, from the middle OH Valley through Middle TN, where residual outflow will likely be present with a destabilized airmass. Weak shear should limit storm organization but isolated damaging gusts are possible. Northern and Central Plains Elevated thunderstorms have persisted throughout much of the night from northeast NE across eastern SD. A second area of thunderstorm activity exists farther norther across north-central ND. An isolated instance of hail is possible over both of these regions for the next few hours before thunderstorm intensity wanes in response to the cessation of the nocturnal low-level jet. Despite rising heights throughout the day, most guidance suggests that low-level convergence along both the lee trough and outflow-modified front in NE will be sufficient for convective initiation this afternoon. Limited vertical shear and a deeply mixed boundary layer suggest an outflow-dominant storm mode with the primary hazard being widely-spaced severe wind gusts. Relatively higher thunderstorm coverage is possible across the central High Plains this evening as warm-air advection supports additional thunderstorm activity. Some clustering of this activity is possible, but vertical shear will be weak and overall storm intensity and organization should be modest. Western Montana A belt of enhanced mid/upper-level flow will extend across the region, to the east of an upper low over the Pacific Northwest. Increasing mid-level moisture and forcing for ascent associated with a weak mid-level disturbance is expected to support an increase in high-based showers and a few thunderstorms during the afternoon and evening. Lapse rates will be steep with strong deep-layer shear, but the absence of appreciable moisture will limit MLCAPE to generally less than 250 J/kg. As such the potential for severe wind gusts is currently too low to warrant 5% wind probabilities.