Severe Storm Risk - Palmetto, MS

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 ACROSS PARTS OF THE UPPER MIDWEST SUMMARY Scattered severe thunderstorms capable of producing large hail, (some 2+ inches), damaging winds, and a couple of tornadoes should occur late this afternoon into tonight across parts of the Upper Midwest. Thunderstorm development is more uncertain farther south into the central Plains, where a conditional risk for large hail and severe gusts will exist late this afternoon into the evening. Upper Midwest into the Central Plains Primary large-scale upper troughing will remain over central Canada today, with an embedded mid-level shortwave trough forecast to eject eastward over the northern Plains into the Upper Midwest through the period. A modest surface response will occur across SD as the shortwave trough ejects eastward, with most guidance suggesting a sub-1000 mb low will develop into eastern SD by 12/00Z. A surface cold front attendant to this low and the primary surface low over central Canada will move east-southeastward across parts of the Upper Midwest into the northern Plains, with a dryline extending southward across the central Plains. A narrow corridor of 60s surface dewpoints will be in place ahead of the cold front/dryline, with diurnal heating aiding moderate destabilization along with steepened mid-level lapse rates. Most guidance, including recent NAM/RAP runs, show minimal MLCIN along/ahead of the front in far northeast SD/western MN by 22-01Z. Convective development appears likely in this time frame across this region, owing to sufficient low-level convergence along the front coupled with forcing for ascent associated with the mid-level shortwave trough. Various NAM/RAP forecast soundings show strongly veering and gradually strengthening winds with height through low/midlevels, and 35-45 kt of deep-layer shear will easily support organized convection. Initial supercells should pose a threat for large hail (isolated 2+ inches possible), but convective mode will probably trend towards clustering fairly quickly given the presence of the cold front and strengthening low-level jet this evening. Any supercells that can remain at least semi-discrete into the early evening may also have a tornado threat with greater low-level shear forecast in this time frame. But, confidence in this scenario occurring remains fairly low due to the mode transition expected. Scattered severe/damaging winds should occur with any clusters or bowing line segments that can develop and spread eastward through the evening. However, the wind threat will likely wane with eastward extent across MN into western WI by late this evening given the narrow zone of destabilization forecast. Convective initiation and overall thunderstorm coverage from southeast SD/southwest MN into the central Plains are highly uncertain and conditional this afternoon/evening, as the better forcing for ascent with the shortwave trough will likely remain across western/northern MN along and northeast of the surface low. Still, a favorable thermodynamic environment and sufficient (25-35 kt) deep-layer shear would conditionally support severe hail/wind with any thunderstorms that can develop and be sustained. There is some signal in model guidance for successful convective initiation across southern NE into northern KS late this afternoon/evening where hotter surface temperatures are forecast. The southern extent of the Marginal Risk has been adjusted to account for this possibility, and the Slight Risk has generally been confined to where greater confidence exists in robust thunderstorm development (far northeast SD into western/northern MN). Mid-South into the Tennessee Valley/Carolinas and Virginia Two weak mid-level perturbations are evident in water vapor satellite imagery this morning across the Southeast: one over AR, and the other along the central Gulf Coast. These features will generally track east-northeastward through the day, and should aid additional thunderstorm development this afternoon. A stalled surface front extending from the ArkLaTex into the TN Valley and northeastward to VA should also provide a focus for thunderstorms. Current expectations are for generally disorganized/pulse-type convection to pose a threat for occasional damaging winds as diurnal heating destabilizes the boundary layer and steepens low-level lapse rates. But, modestly enhanced mid-level flow across parts of the Mid-South and VA could promote loosely organized clusters with some damaging wind threat as well.