Subj : DAY2SVR: Nws Storm Prediction Center Norman Ok To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Thu Jul 27 2023 17:43:08 ACUS02 KWNS 271743 SWODY2 SPC AC 271741 Day 2 Convective Outlook CORR 1 NWS Storm Prediction Center Norman OK 1241 PM CDT Thu Jul 27 2023 Valid 281200Z - 291200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS IOWA INTO THE SOUTHERN GREAT LAKES... CORRECTED FOR SUMMARY ....SUMMARY... Widely scattered severe thunderstorms are possible on Friday and Friday night across a large portion of the Midwest. ....Synopsis... Moderate to strong mid-level winds will remain along the northern periphery of an upper-level ridge. This flow will be confined to the northern Plains into the upper Midwest, though some amplification of the ridge could push moderate mid-level flow into the lower Great Lakes as well. A surface boundary will extend from the northern Plains into parts of the upper Midwest. A surface low is forecast to deepen slightly in the mid-Missouri Valley. Convective outflow and potential MCVs will also be present, but the location of these features is a bit uncertain. ....Lower Great Lakes/Midwest... Convection within the upper Mississippi Valley on Thursday night into Friday morning will play a role in how convection evolves during Friday afternoon. Guidance is variable in the placement of the outflow/MCV from this activity. However, the general consensus places these features within southern Wisconsin into parts of the upper Ohio Valley. South of the outflow, strong buoyancy is expected to develop. Shear will be strongest along and north of the boundary and decrease with southward extent. Forcing for ascent will generally be nebulous outside of areas impacted by the MCV. The expectation is for a cluster or two of storms to develop and progress eastward/southeastward into the MLCAPE reservoir. Large hail would be possible with initial activity before upscale growth occurs and severe/damaging winds would become the primary threat. A corridor of greater severe wind potential could develop given the clustering and strong instability, but uncertainty in the placement of boundaries and the eventual convective evolution precludes an increase in probabilities. Convection developing within parts of Montana may be ongoing at the beginning of the period. This activity and associated MCV could potentially intensify if it is able to progress into the greater buoyancy within South Dakota/Nebraska. This activity would also pose a risk of primarily strong/damaging winds and isolated large hail possible as well. Confidence in this scenario is also too low for any increase in wind probabilities. ....Southwest Montana... Stronger mid-level winds will persist across the northern Rockies. Convection is likely to develop within the higher terrain. Steep low and mid-level lapse rates will allow for strong wind gusts to reach the surface. Marginally severe hail will also be possible. ....Northern Maine... Strong westerly mid to high-level flow accompanying the aforementioned speed max will overspread the region during the day. It appears at least marginal destabilization will occur with surface dewpoints well into the 60s. A band of storms along a frontal zone will probably push eastward into Maine during the afternoon/early evening. Isolated severe gusts are the primary hazard. ...Wendt.. 07/27/2023 $$ = = = To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM. --- SBBSecho 3.14-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .