Subj : MESO: Mesoscale Discussion 1578 To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sun Jul 06 2025 18:40:06 ACUS11 KWNS 061838 SWOMCD SPC MCD 061838=20 NEZ000-COZ000-WYZ000-062115- Mesoscale Discussion 1578 NWS Storm Prediction Center Norman OK 0138 PM CDT Sun Jul 06 2025 Areas affected...Northeast Colorado to southeast Wyoming and western Nebraska Concerning...Severe potential...Watch possible=20 Valid 061838Z - 062115Z Probability of Watch Issuance...60 percent SUMMARY...Thunderstorms developing within the higher terrain of the central Rockies will spread east and intensify through the afternoon. As this occurs, the threat for severe winds, and possibly large hail, will increase. Watch issuance is probable later this afternoon as thunderstorms increase in coverage and intensity. DISCUSSION...Latest GOES imagery and lightning data shows a gradual uptick in convection within the higher terrain of central to northern CO and far southern WY as daytime heating drives increasing orographic ascent within a weakly capped air mass. This initial activity is expected to spread east into the High Plains over the coming hours given 30-40 knot westerly flow within the CAPE-bearing layer. Storm intensification is expected as convection overspreads a relatively moist low-level air mass (dewpoints remain in the mid to upper 50s downstream) and as lingering inhibition is removed via deepening boundary-layer heating/mixing.=20 Across southeast WY and western NE, slightly stronger zonal flow aloft coupled with weak easterly low-level winds should promote adequate deep-layer shear for a couple of supercells with an attendant large hail risk (possibly up to 2 inches in diameter). The tornado threat may also be locally greatest across this region due to augmented low-level shear/SRH on the immediate cool side of a residual outflow boundary emanating out of central NE. Further south across CO, observed dewpoint depressions and short-term forecast soundings suggest LCL heights should approach 2.5 to 3 km as temperatures warm into the upper 80s, which will promote strong downdraft evaporative cooling and accelerations as well as rapid cold pool production. Strong to severe downburst winds and sporadic large hail appear likely within initially discrete cells moving off the terrain and/or developing within the DCVZ, but upscale growth into organized clusters is anticipated later this afternoon/evening with a more widespread severe wind risk (with gusts possibly as high as 70-80 mph). Watch issuance is probable as these threats begin to emerge in the coming hours. ...Moore/Hart.. 07/06/2025 ....Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!9mv-v_4V-xUhpAmpDSrqhQsxJst7wx-y8YKhWqjZmiKnN1gda63EV5UaLDqON-rV4HiXrrG2S= fJLxy25iDYOhOepKqI$ for graphic product... ATTN...WFO...LBF...GLD...PUB...BOU...CYS... LAT...LON 40170514 41190520 41680493 42020458 42360407 42430360 42350311 41860264 41360256 40730251 40160253 39340260 39050292 38330454 38280476 38310502 38560514 40170514=20 MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 95 MPH MOST PROBABLE PEAK WIND GUST...65-80 MPH MOST PROBABLE PEAK HAIL SIZE...1.50-2.50 IN =3D =3D =3D 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 3.20-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .