Subj : DAY1SVR: Enhanced Risk To : All From : Mike Powell Date : Fri Jul 07 2023 19:17:00 ACUS01 KWNS 072002 SWODY1 SPC AC 072000 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0300 PM CDT Fri Jul 07 2023 Valid 072000Z - 081200Z ....THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS THE OK/NORTHERN TX PANHANDLES INTO FAR NORTHWEST OK... ....SUMMARY... Scattered severe thunderstorms are expected late this afternoon through tonight across portions of the central and southern Plains. Large to very large hail and severe/damaging winds should be the primary risks, with the greatest potential for significant (75+ mph) winds across parts of the Oklahoma/Texas Panhandles into western Oklahoma late this afternoon and evening. ....20Z Update... The primary change with this outlook is to trim parts of the Marginal Risk across parts of the northern and central Plains, generally behind a cold front across parts of ND/MN, and in the wake of earlier convection across parts of the central Plains. Otherwise, isolated supercells will be possible this afternoon across eastern CO into northeast NM, with upscale growth into a severe-wind producing MCS expected across parts of the TX/OK Panhandles by this evening. See MCD 1455 for more information regarding the short-term threat across the southern High Plains, MCD 1454 for more information across northern New England, and MCD 1456 for more information across the northern Plains. Also see the previous discussion below for more information. ...Dean.. 07/07/2023 ..PREV DISCUSSION... /ISSUED 1123 AM CDT Fri Jul 07 2023/ ....Southern/Central Plains...Southern/Central High Plains... Ongoing MCS across central OK is expected to continue weakening over the next few hours as it moves into the more stable conditions downstream in the Arklatex vicinity. A large ACCAS field has developed in the wake of the this MCS across the TX Panhandle, supported by modest isentropic ascent atop the MCS outflow. A few elevated storms are possible within this environment this morning, but warming and drying mid-levels should lead to their dissipation before this afternoon. The evolution of this MCS and additional elevated storms this morning have helped to reinforce a subtle surface boundary extending across the western TX Panhandle through far northeast NM and into southeast CO, where it intersects the lee troughing. Additionally, a cold front is forecast to continue pushing southward/southeastward across eastern CO and the adjacent central Plains. This front will likely be through much of eastern CO by the late afternoon, with post-frontal upslope in place across southeast CO. Afternoon thunderstorm development is anticipated along the higher terrain of northeast NM and southern CO, with an initially supercellular mode possible over southeast CO. Very large hail is the primary severe risk with these supercells, but the high surface vorticity environment suggests a tornado or two is possible as well. Highest storm coverage is anticipated south of the Palmer Divide. An isolated storm or two capable of hail is possible north of the divide. These supercells are then expected to move downstream, interacting with the now modified boundary farther east across the northern TX/OK Panhandles. Convergence along this boundary will likely provide a favored corridor for upscale growth. High storm bases coupled with steep low-level lapse rates will support strong outflow, with significant severe winds of 75+ mph possible with this complex as it moves quickly eastward. Other supercells may form in the strengthening warm advection regime across south-central KS/northern OK this evening. Steep mid-level lapse rates and moderate deep-layer shear will support the potential for very large hail. Some threat for severe/damaging winds may eventually develop with this convection if it can grow upscale into one or more small clusters while spreading generally southeastward tonight. ....Central Plains into the Mid MS Valley... Decaying MCS continues to push eastward across western IA/northern MO, with a few thunderstorms ongoing along its southern periphery across far northwest MO. Redevelopment/restrengthening appears possible downstream of theses storms over northern and east-central MO/west-central IL as the air mass destabilizes. This area will be on the southern periphery of the stronger mid-level flow, supporting the potential for a few strong to severe storms capable of damaging gusts. Additional redevelopment is possible farther west over the southeast NE/northeast KS vicinity as outflow for the IA/MO MCS as well as outflow from the elevated cluster over central KS moves into the region. However, ongoing cloud cover may limit destabilization, precluding this potential redevelopment until later this evening. ....Northeast/Mid-Atlantic... Daytime heating of a moist low-level airmass should encourage the development of weak to moderate instability by this afternoon across parts of the Northeast and Mid-Atlantic. Glancing ascent associated with a shortwave trough over Quebec and weak low-level convergence along a surface trough extending from northern NY southward through central VA will likely foster at least scattered thunderstorm coverage this afternoon and evening. Deep-layer shear is forecast to remain fairly modest, generally 25 kt or less, and weakening with southward extent across the Mid-Atlantic. Still, some loosely organized thunderstorm clusters capable of producing damaging gusts are possible, particularly from central NY into northern ME where shear is strongest. $$ --- SBBSecho 3.14-Linux * Origin: Ilink: CCO - capitolcityonline.net (454:1/105) .