Subj : DAY2SVR: Marginal Risk To : All From : Mike Powell Date : Mon Aug 21 2023 08:41:00 ACUS02 KWNS 210438 SWODY2 SPC AC 210437 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1137 PM CDT Sun Aug 20 2023 Valid 221200Z - 231200Z ....THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS TUESDAY ACROSS PARTS OF DEEP SOUTH TEXAS AND PARTS OF WESTERN UTAH...AND TUESDAY NIGHT ACROSS PARTS OF WESTERN UPPER MICHIGAN...ADJACENT NORTHWESTERN WISCONSIN INTO PARTS OF WESTERN LOWER MICHIGAN... ....SUMMARY... A tropical disturbance emerging from the Gulf of Mexico Tuesday may be accompanied by showers and thunderstorms with gusty winds and at least some potential for a tornado or two across parts of Deep South Texas. Strong thunderstorms posing at least some risk for severe weather are also possible near the western slopes of the Wasatch Mountains Tuesday afternoon, and across parts of the upper Great Lakes region Tuesday night. ....Synopsis... Models continue to indicate that a prominent warm-core ridge, centered at mid-levels across the lower Missouri Valley, will generally be maintained through this period. However, there may be some suppression of mid-level heights, particularly on the northwestern periphery of the ridge across the northern Rockies, as several perturbations progress through a broadly confluent regime downstream of mid-level troughing and an embedded low slowly progressing inland across the Pacific Northwest. Within the easterlies to the south of the ridge, one tropical perturbation appears likely to continue migrating inland of the lower Texas coast through the Rio Grande Valley, near and south of the Texas Big Bend. A broader upstream wave may slowly shift west-northwestward across the Caribbean/Bahamas/south Florida vicinity. Strongest destabilization Tuesday, including the development of large mixed-layer CAPE with daytime heating of seasonably high boundary-layer moisture content, appears likely to once again be focused across parts of the Ozark Plateau and middle Mississippi Valley into portions of the Upper Midwest. However, it still appears that sustained deep convective development within this environment will be suppressed by large-scale subsidence and inhibition associated with warm and dry mid-levels. ....Deep South Texas... There remains considerable spread among the model output concerning the strength of the tropical perturbation, or perhaps developing tropical cyclone, likely to emerge from the Gulf of Mexico. However, NAM forecast soundings in particular, continue to depict enlarging clockwise-curved low-level hodographs, coincident with a weakly destabilizing tropical boundary layer, as the perturbation progresses inland Tuesday morning. This regime may become conducive to the development of a few low-topped supercell structures, with embedded mesocyclones posing a risk for producing tornadoes. ....Great Basin... As one short wave impulse accelerates inland across the Sierra Nevada into the Great Basin, models indicate a belt of strengthening southerly mid-level flow (including 50+ kts around 500 mb) near/west of the Wasatch. Based on forecast soundings, this may contribute to supercell wind profiles during the day Tuesday, within a relatively moist environment. Due to generally weak lapse rates, CAPE may remain rather weak, and the extent of the severe weather potential remains uncertain. However, convection capable of produce strong surface gusts seems possible, and a tornado may not be out of the question. ....Upper Great Lakes... A slow moving warm frontal zone may once again become a focus for strong thunderstorm development Tuesday night, aided by a nocturnally strengthening southwesterly low-level jet. Forecast soundings suggest that sizable CAPE may develop above a fairly deep near-surface stable layer. This probably will minimize the risk for convection capable of produce strong surface gusts, but the convective-layer shear may be sufficient for a few storms posing a risk for severe hail. ...Kerr.. 08/21/2023 $$ --- SBBSecho 3.14-Linux * Origin: Ilink: CCO - capitolcityonline.net (454:1/105) .