Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Mon Jul 17 2023 12:55:13 ACUS01 KWNS 171255 SWODY1 SPC AC 171253 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0753 AM CDT Mon Jul 17 2023 Valid 171300Z - 181200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE NORTH-CENTRAL PLAINS AND OZARKS/OHIO VALLEY... ....SUMMARY... Severe storms producing large hail and damaging wind gusts are mainly expected from the Black Hills southeastward into Nebraska tonight, and across portions of the Ozarks and Lower Ohio Valley today. ....Ozarks and Ohio Valley... Scattered thunderstorms continue to generally weaken across Kentucky early this morning, with somewhat more regenerative storms extending westward across southern Missouri. This convection and its related cold pool/residual cloud cover will likely effectively modify the warm-sector environment to the south of a southward-sagging front. To the east/northeast of these early day storms, a diurnally warming/destabilizing boundary layer will support an increase in thunderstorm coverage and intensity into the afternoon near/ahead of the front, with some potential for damaging winds. Other storms should increase across the Lower Missouri Valley/Ozarks, possibly related to a potential persistence of upstream storms across eastern Nebraska/northern Missouri, and/or otherwise near the convectively reinforced effective front across southeast Missouri. Beneath a seasonally strong belt of northwesterly flow aloft, a mix of semi-discrete cells and clusters are expected. Steep low-level lapse rates will aid in strong outflow and potentially damaging gusts, especially with any organizing clusters. Otherwise, isolated cells may be capable of producing large hail in the presence of steep mid-level lapse rates and elongated hodographs. ....Eastern Wyoming/Black Hills/Nebraska... A sharpening lee trough ahead of the northern Rockies upper trough will result in moist low-level upslope flow into the Black Hills/eastern Wyoming and southeast Montana vicinity. Although the proximity of the upper ridge may somewhat temper the extent of deeper convection, at least isolated thunderstorms are expected to develop by late afternoon/early evening in a moderately unstable and strongly shear environment, with storms increasing in coverage toward/after sunset. Steep lapse rates and long straight hodographs will support large to locally very large (greater than 2 inch diameter) hail. As the low-level jet strengthens during the evening, upscale development into a bowing MCS is possible as convection tracks southeastward across western/southern South Dakota and Nebraska. Sporadic hail and damaging gusts may accompany this MCS during the evening and overnight hours. ....Northern Great Basin and Central/Eastern Montana... Moderate to strong west-southwest mid/upper-level flow will overspread the region ahead of the northern Rockies upper trough. Steep mid-level lapse rates and moistening will support MLCAPE around 500-1250 J/kg. Well-mixed boundary layers will result in mostly high-based, low-precipitation convection capable of sporadic strong dry microburst winds from far northeast Nevada/northern Utah into central Montana. With eastward extent into parts of eastern Montana, deeper boundary-layer moisture will result in the potential for isolated strong gusts as well as hail. ....Eastern portions of Kansas/Oklahoma to southwest Missouri... While forecast confidence remains limited, and storms have tended to weaken as they move southeastward in the pre-dawn hours, various short-term guidance suggests that ongoing widely scattered convection across north-central Kansas/southeast Nebraska could intensify today. This would be focused near the terminus of a moderate-strength low-level jet, with potential intensification occurring with a diurnally warming boundary layer. Given the degree of expected destabilization and strength of northwesterly flow aloft, strong wind gusts and hail should be expected if storms indeed develop/intensify. ...Guyer/Kerr.. 07/17/2023 $$ = = = 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) .