Subj : MESO: Mesoscale Discussion 0210 To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue Feb 28 2023 12:27:40 ACUS11 KWNS 281227 SWOMCD SPC MCD 281227=20 CAZ000-281630- Mesoscale Discussion 0210 NWS Storm Prediction Center Norman OK 0627 AM CST Tue Feb 28 2023 Areas affected...the northern Sierra Nevada Concerning...Heavy snow=20 Valid 281227Z - 281630Z SUMMARY...Snow is expected to gradually intensify this morning along the western slopes of the Sierra Nevada, to the northwest through west and south of Tahoe Valley, including the Interstate 80 corridor. Persistent rates on the order of 2-3 inches per hour appear possible by 8-10 AM PST. DISCUSSION...As an intense mid/upper jet continues to dig offshore of the Pacific Northwest coast, one short wave perturbation has progressed inland across the Great Basin, while another begins to advance inland of the southern Oregon/northern California coast this morning. In response to these developments, lower/mid-tropospheric warm advection has been focused inland of the northern/central California coast into the western slopes of the northern Sierra Nevada, where snow has persisted overnight. A gradual increase in snow rates may be underway along the mountains to the east of Red Bluff. This appears likely to continue, while also developing southward along the higher terrain to the west and southwest of Tahoe Valley, as south to southwesterly flow in the 3000-8000 foot layer strengthens to 40-50 kt through 16-18Z.=20=20 It appears that strengthening forcing for ascent in response to warm advection and orographic lift will be aided by increasingly divergent upper flow. Rapid Refresh forecast soundings suggest that this will include strengthening upward vertical motion within a saturated and rising dendritic growth zone (layer with temps around -15 C rising above the 700 mb level), as precipitable water also increases to near and above .3 inches. All of this is expected to result in increasingly heavy snow, including rates up to 2-3 inches per hour by mid morning, which may continue into the afternoon.=20 While the lower/mid-levels warm, it appears that the lower snow levels may remain around or perhaps just a bit below 2000 feet. ...Kerr.. 02/28/2023 ....Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!8ms-s7Zrsge9xKZ8SxQmA528W_fdqt_9bB-OyPIkvgAsgzH0BpxClgQJ0NpaMwBwhC8081gLX= lnu4vHWN2qnsbbv5dQ$ for graphic product... ATTN...WFO...STO... LAT...LON 40262151 39252042 38742017 38532031 38392045 38372062 38772083 39422132 39882166 40262151=20 =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 3.14-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .