Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue Jul 18 2023 16:35:56 ACUS01 KWNS 181635 SWODY1 SPC AC 181634 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1134 AM CDT Tue Jul 18 2023 Valid 181630Z - 191200Z ....THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER SOUTHEAST MISSOURI...SOUTHERN ILLINOIS...AND WESTERN PORTIONS OF KENTUCKY AND TENNESSEE... ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER THE NORTHERN PLAINS AND ALSO ACROSS THE NORTHEAST U.S.... ....SUMMARY... Thunderstorms associated with large hail and damaging wind gusts are expected today into tonight from the Lower Missouri Valley southeastward into the Tennessee Valley. Other strong to severe storms are expected in areas across the Northeast States and northern/central Plains. ....Middle/Lower Missouri Valley to Tennessee Valley... Ongoing bowing complex of strong/severe storms continues moving southeast at 40-45 kt across southeast MO. Downstream heating of a very moist environment (dew points 75-80 Deg F) and seasonably strong mid-level northwesterly flow averaging 40-45 kts is expected to result in a continued southeast movement into an increasingly favorable environment for a forward-propagating MCS/potential for significant severe gusts. Please refer to recently-issued MCD 1613 for the latest short-term thinking in this area. Additionally, another round of elevated thunderstorms is expected to develop later today along the convectively influenced northwest/southeast-oriented boundary across Missouri. This may include elevated supercells with a threat for large (isolated very large) hail given strong elevated instability and substantial deep layer shear. With time, upscale growth will be possible and a severe wind threat could materialize. ....Northern Plains... Low-level moisture advection and surface heating will lead to moderate-strong instability across central North Dakota and South Dakota by this afternoon. This instability, combined with convergence from an approaching/sharpening cold front and ascent with a mid-level shortwave trough, should be sufficient for strong/severe thunderstorm development near the front this afternoon. Mid-level winds of 45-55 kt will contribute to favorable wind profiles for supercells and related risk for large hail, some potentially 2+ inches in diameter. ....Northeast/Mid-Atlantic States and New England... Modest height falls will continue to overspread the region, influenced by moderately strong cyclonic mid-level flow with an upper-level trough over northern Ontario/Quebec. Relatively long hodographs during peak heating/maximized instability will support some potential for sustained/organized storms capable of wet microbursts and isolated wind damage. Some hail will also be possible. Refer to MCD 1614 for short-term thinking in this area. ....Central High Plains... A few thunderstorms are possible late this afternoon as low-level upslope flow evolves, with increasing low-level moisture to the north of a surface low. The favorable environment may be relatively short-lived given the late-day increase in moisture, but a favorable environment will exist for a few severe thunderstorms in an environment with 2000+ J/kg MLCAPE and supercell wind profiles. ....Great Basin... A deeply mixed boundary layer is expected today across the Great Basin with ample instability for scattered thunderstorms across much of the region. A belt of stronger mid-level winds of 25-30 kt will exist from east-central Nevada into north-central Utah. This may support some storm organization with the potential for isolated strong/severe wind gusts given the well-mixed sub-cloud layer/steep low-level lapse rates. ....Southern Arizona... Thunderstorms should develop over the Rim/White Mountains and higher terrain of southeast Arizona this afternoon. The region will be nearly coincident with the upper high. While mid-level steering flow will be weak, a westerly component of near-surface winds will likely support propagation into the desert floor, particularly across southeast Arizona within a relatively moist but hot/deeply mixed boundary layer. Some strong, potentially severe outflow winds may occur late this afternoon/early evening. ...Bunting/Weinman.. 07/18/2023 $$ = = = 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) .