Severe Storm Risk - Harristown, IL

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 SOUTHERN GREAT LAKES/MIDWEST...CENTRAL HIGH PLAINS...AND OZARKS/MID-SOUTH INTO THE LOWER MISSISSIPPI VALLEY SUMMARY Isolated to widely scattered severe thunderstorms are forecast today across parts of the southern Great Lakes into the Midwest, central/southern High Plains, and the Ozarks into the Mid-South and Lower Mississippi Valley. Severe/damaging winds should be the main threat across these regions, though large hail is also possible, particularly across the central High Plains. Southern Great Lakes into the Midwest A mid-level shortwave trough over the upper Great Lakes this morning will progress eastward today across southern Ontario. The basal portion of this trough will overspread parts of the southern Great Lakes and Midwest, with a surface cold front moving east-southeastward across these regions as well. Lapse rates aloft are forecast to remain rather poor, which may tend to limit updraft strength to some extent. Still, a corridor of destabilization is expected along/ahead of the front through the afternoon, with at least moderate instability likely from eastern IL northeastward into southern Lower MI. Thunderstorms should develop along/ahead of the front as convective temperatures are reached by 19-22Z. Low/mid-level winds will tend to remain fairly modest and veered to westerly, with up to 25-35 kt of deep-layer shear fostering some updraft organization. A mix of multicell clusters and marginal supercells should pose a threat for both hail and damaging winds, with the wind threat potentially becoming the primary risk with eastward extent into the Midwest as thunderstorms grow upscale. A brief embedded tornado may also occur, but low-level flow is forecast to remain rather veered, with limited hodograph curvature noted in most NAM/RAP forecast soundings. The overall severe threat will likely diminish quickly this evening as convection outpaces the low-level moisture/instability, and as nocturnal cooling of the boundary layer occurs. Ozarks into the Mid-South and Lower Mississippi Valley Thunderstorms have developed this morning across southeast MO/far southern IL, and they should continue to track south-southeastward into the Mid-South along the MUCAPE gradient noted in latest mesoanalysis. While sub-severe for now given substantial MLCIN present, there is some potential for this activity to persist and eventually strengthen later today across parts of western TN into northern MS and vicinity as the boundary layer gradually destabilizes. Have adjusted/expanded wind probabilities a bit eastward in western TN/northern MS into northern/central AL to account for this possibility. Otherwise, additional thunderstorm development is also likely this afternoon along/near a weak surface front from southern MO into AR and eastern OK. This activity may be aided by a remnant MCV that will move eastward across the southern Plains through the day. Modest deep-layer shear should support some updraft organization, with multicell clusters likely the dominant mode. High total precipitable water values and large buoyancy will support robust downbursts with primarily a scattered damaging wind threat. Occasional hail may also occur with the strongest cores given the degree of instability forecast. Some high-resolution guidance continues to show a southward-moving storm cluster across the lower MS Valley this evening/tonight. As such, there is potential for at least isolated damaging winds to persist across parts of southern LA/MS. Central/Southern High Plains Around 25-35 kt of west-northwesterly mid-level flow will be present over the southern/central High Plains today, with a mid/upper-level ridge remaining centered over the Southwest/Four Corners. Modest low-level upslope flow across the central High Plains should support convective initiation by early/mid afternoon over the higher terrain and Front Range. Moderate instability aided by modestly steepened mid-level lapse rates and sufficient deep-layer shear should all act to aid updraft organization, with both supercells and clusters possible. There is still some uncertainty with convective development farther east across southwest NE this afternoon along/near a front. But, any thunderstorms that can form and persist across this area would also pose a severe risk. Both large hail and severe gusts may occur with convection that spreads east-southeastward through the afternoon and evening, with some potential for upscale growth/additional clustering into western KS this evening. Farther south across the southern High Plains, mid-level flow and related deep-layer shear should be somewhat weaker. Still, convection that develops across central into eastern NM may become loosely organized while posing an isolated threat for severe gusts given the presence of a very well-mixed boundary layer. This threat may continue into parts of the OK/TX Panhandles and west TX through the evening before eventually weakening.