Subj : DAY2SVR: Nws Storm Predic To : All From : Mike Powell Date : Tue Jun 20 2023 16:27:00 ACUS02 KWNS 201734 SWODY2 SPC AC 201732 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1232 PM CDT Tue Jun 20 2023 Valid 211200Z - 221200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE CENTRAL AND SOUTHERN PLAINS... ....SUMMARY... Isolated to scattered severe thunderstorms are possible on Wednesday across portions of the Plains. Large hail and severe gusts will be the main hazards with this activity. Isolated strong storms also will be possible across parts of the Southeast, with an accompanying risk for damaging gusts. ....Synopsis... Little change to the large-scale pattern is expected on Wednesday, with a deep upper trough remaining in place over much of the west into the northern High Plains, an upper ridge from the southern Rockies into parts of the southern High Plains, and a persistent upper low/trough over the Southeast. At the surface, an initially stationary front will extend from the Gulf Coast northwestward toward the ArkLaTex and into the southern High Plains. This front may tend to move westward across the southern Plains Wednesday evening. Another weak cold front will become nearly stationary across the northern Plains. ....CO Front Range into parts of the central/southern Plains... Guidance varies regarding the placement (if any) of ongoing storm clusters Wednesday morning across the central Plains. Some CAM solutions take an ongoing storm cluster and intensify it through the day as it moves south-southeastward along the periphery of the upper ridge, which would potentially result in a notable severe-wind risk across parts of OK into central/east TX as the downstream environment becomes strongly unstable during the afternoon. Other guidance suggests little to no threat in these areas during the day, as the severe threat focuses farther west toward the High Plains by late afternoon/evening. Even if no substantial MCS development occurs during the day, widely scattered strong storms may be possible along the front, and also emerging from a hot and well-mixed environment across parts of southwest TX. Uncertainty remains quite high, but severe probabilities have been expanded southeastward to cover these potential threats. Otherwise, moist post-frontal low-level flow will support thunderstorm development across parts of the central High Plains and the CO Front Range during the afternoon and evening. Midlevel flow will remain rather modest, but favorably veering wind profiles will result in effective shear of 30-40 kt, supporting the potential for a few supercells with an initial threat of large (possibly golfball-size or larger) hail. A tornado or two will also be possible, especially across parts of southeast WY, where a the most favorable overlap of instability and stronger low-level shear is currently forecast. With time, upscale growth into one or more clusters will be possible, with an increasing severe-wind risk. There is some potential for an organized MCS to develop and move southeastward across the southern High Plains Wednesday night, though this scenario will depend in part on the extent of convective overturning that occurs downstream earlier in the day. ....Northern Plains... Some uncertainty remains regarding the convective evolution on Wednesday across the Dakotas, with morning storms potentially leading to a complex evolution later in the day. Stronger midlevel flow will remain displaced well northwest of the effective warm sector, but a few strong storms may develop during the afternoon near a weakening frontal boundary, with a threat of isolated hail and strong gusts. Farther west, a few stronger cells/clusters may develop across parts of northeast WY, within a modestly moist post-frontal regime. Deep-layer flow/shear will be stronger in this area, but buoyancy may tend to remain somewhat limited. Isolated hail and severe gusts cannot be ruled out in this area. One or more clusters may eventually move northeastward into the Dakotas Wednesday night, which could pose a threat of isolated strong/severe gusts, depending on the magnitude of buoyancy in the wake of potential convection earlier in the day. ....Southeast... To the south and east of the persistent upper low across the Southeast, widespread convection is expected during the day on Wednesday, which may persist into Wednesday night near the immediate Gulf Coast. Modest deep-layer flow/shear and moderate buoyancy will support some stronger cells/clusters, with a primary threat of locally damaging gusts. Weak midlevel lapse rates will tend to limit the hail threat, though small to near-severe hail cannot be ruled out with the strongest storms. ...Dean.. 06/20/2023 $$ --- SBBSecho 3.14-Linux * Origin: Ilink: CCO - capitolcityonline.net (454:1/105) .