Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sun Jul 21 2024 20:01:01 ACUS01 KWNS 212000 SWODY1 SPC AC 211959 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0259 PM CDT Sun Jul 21 2024 Valid 212000Z - 221200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PARTS OF CENTRAL AND SOUTHERN ARIZONA... ....SUMMARY... Scattered severe thunderstorms are forecast this afternoon into the evening across parts of central and southern Arizona. Isolated severe storms are also possible from southern Colorado to eastern New Mexico. ....20Z Update... The primary change to the outlook was the introduction of a wind-driven (15 percent) Slight Risk over portions of central and southern Arizona. Thunderstorms are increasing in coverage along the Mogollon Rim early this afternoon, and with the approach of a subtle midlevel wave, this trend should continue. These recent convective trends have increased confidence in a sufficient amount of storms (and related congealing outflow) spreading southward off the Rim -- with a risk of scattered severe gusts into this evening. For additional details, reference MCD #1690. ...Weinman/Smith.. 07/21/2024 ..PREV DISCUSSION... /ISSUED 1126 AM CDT Sun Jul 21 2024/ ....Synopsis... Water-vapor imagery late this morning shows a mid-level disturbance moving south-southeast across WY/CO to the east of a mid-level ridge located over the Interior West. A mid-level shortwave trough will move northward along the Pacific Northwest coast into British Columbia by tonight. Farther east, a mid-level trough/low centered over the lower MO/mid MS Valleys will meander slowly eastward. ....Sangre de Cristos and adjacent escarpment/plains... Scattered orographically favored thunderstorm development is forecast by early to mid afternoon across the mountains ahead of the aforementioned weak upper disturbance. A seasonably moist airmass (reference 12 UTC Albuquerque raob data) is in place across the region with considerable cloud breaks and partly sunny skies noted in visible-satellite imagery. Strong heating will foster upwards of 500-1250 J/kg MLCAPE by peak heating. Modest deep-layer shear will limit overall convective organization potential, but the stronger multicells (becoming numerous in coverage) will likely be capable of an isolated hail/wind risk through the early evening before this activity dissipates. ....AZ... A weak PV anomaly was noted in upper-layer water-vapor imagery this morning over northern AZ. This upper feature may aid in storm development near the Mogollon Rim later this afternoon with scattered thunderstorms forecast. A hot and a deeply mixed sub-cloud layer in the lower desert will likely support some risk for severe gusts via evaporatively cooled downbursts as this activity slowly pushes southward late this afternoon through the evening. Isolated to widely scattered severe gusts (60-75 mph) are possible with the stronger cores and outflow surges. ....Central/eastern Oregon into northwest NV... Model guidance indicates scattered thunderstorms are forecast to develop later this afternoon on the southeast periphery of the mid-level shortwave trough glancing the region. Inverted-V profiles per forecast soundings suggest gusty winds may accompany the stronger downdrafts. The overall severe risk appears too limited in time/space to include a 5-percent severe wind highlight. $$ = = = 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) .