Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sat Aug 09 2025 19:58:46 ACUS01 KWNS 091958 SWODY1 SPC AC 091957 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0257 PM CDT Sat Aug 09 2025 Valid 092000Z - 101200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE FRONT RANGE TO THE CENTRAL PLAINS AND WESTERN GREAT LAKES.... ....SUMMARY... Scattered strong/severe storms are possible through tonight from eastern Colorado, across the Central Plains and into the western Great Lakes. Isolated damaging wind gusts are possible in southeast Arizona. ....20z Update Western Great Lakes... A large convective complex remains ongoing as of this afternoon from portions of eastern WI, into eastern IA and northern MO. Diurnal heating ahead of the remnant storms and outflow should promote some redevelopment/organization this afternoon and evening. Behind the system, widespread cloud cover and precipitation has largely overturned the air mass. This suggests little if any redevelopment and severe risk is expected. The Slight Risk for damaging gusts will be maintained ahead of the ongoing storms, with severe probabilities removed where air mass recovery is unlikely in the wake of the complex. See MCD#1914 for short-term guidance. ...Central Plains to Midwest... On the southwestern flank of the ongoing convective complex over the Upper Midwest, gradual air mass recovery is ongoing ahead of a slow-moving cold front, likely continuing into this evening. Afternoon model guidance shows an increase in low-level warm air advection from a 35-50 kt low-level jet is likely along the front and prior outflow intersection across southeast NE and northwest KS. The increase in ascent should foster widespread thunderstorms after dark across the central Missouri Valley. Very large, but likely elevated, CAPE along the boundary (3500+ J/kg) should support one or more clusters with damaging winds and some hail potential tonight. Minor changes were made to the Slight Risk area to better align with current frontal position and guidance. ....Front Range... Confidence continues to increase that upslope flow and the passage of a mid-level trough should support scattered thunderstorms, including supercells, in several rounds through tonight. Storms should continue developing this afternoon off the higher terrain over eastern CO/WY. Moderate buoyancy, steep lapse rates and 40+ kt of deep-layer shear suggests hail (some potentially 2+ inch) will be likely along with the potential for damaging gusts and a tornado or two. Minimal changes were made to this outlook area for the latest guidance, see MCD#1913 for short-term info. ...Lyons.. 08/09/2025 ..PREV DISCUSSION... /ISSUED 1122 AM CDT Sat Aug 09 2025/ ....IA/WI Vicinity... An intense small-scale MCS affected parts of eastern NE and western IA overnight and this morning. The remnants of this system are moving across eastern IA and have weakened below severe limits. This activity will likely persist eastward across WI and into parts of Upper MI through the day, but a sagging cold front ahead of the storms coupled with some cloud cover limit the confidence it can re-intensify to severe levels. Nevertheless will maintain a SLGT risk for the areas ahead of this activity. ....NE/MO/IA tonight... Substantial airmass stabilization has occurred across this area in the wake of the overnight storms. It appears likely that relatively strong heating and return of a very moist air mass will result in strong CAPE values by early evening. A strengthening low-level jet will enhance lift along the retreating outflow boundary, likely resulting in rapid thunderstorm development after 00z over northeast KS. These storms will build east-northeastward into southern IA/northern MO through the evening/night with a risk of upscale organization and damaging winds/hail. ....CO/NE/KS... Southeasterly low-level winds will help maintain a very moist/unstable air mass over eastern CO this afternoon, with dewpoints in the 60s and MLCAPE values of 2500+ J/kg. Present indications are that thunderstorms will form off the Palmer Ridge by mid-afternoon and spread eastward toward western KS this evening. Forecast soundings show an environment favorable for supercell structures. Very large hail, damaging winds, and a tornado or two are possible. This activity may persist into the night, spreading eastward across central KS. After dark, persistent southeasterly low-level winds into the foothills of central/southern CO will interact with an approaching shortwave trough to pose the risk of continued re-development of strong/severe storms, with very large hail possible. ....Southeast AZ... Considerable low/mid level moisture are present today over parts of southeast AZ and southwest NM, with dewpoints in the low 60s. Full sunshine will result in scattered afternoon thunderstorms over the higher terrain that will propagate westward during the evening. Locally damaging wind gusts are possible. $$ = = = 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 3.28-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .