Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sun Sep 03 2023 16:29:19 AWUS01 KWNH 031629 FFGMPD IDZ000-NVZ000-ORZ000-032200- Mesoscale Precipitation Discussion 1030 NWS Weather Prediction Center College Park MD 1228 PM EDT Sun Sep 03 2023 Areas affected...Northern & Central Nevada with Adj. SE OR & SW ID... Concerning...Heavy rainfall...Flash flooding likely Valid 031630Z - 032200Z SUMMARY...Main upper low is starting to drift east supporting more favorable unstable environment for stronger and more numerous thunderstorms across the Great Basin capable of 1-1.5"/hr rates and localized totals to 2.5". Given coverage and efficiency of storms, scattered to numerous small scale/localized incidents of flash flooding are likely this afternoon. DISCUSSION...GOES-W WV suite depicts main core of the upper-low is starting to shift eastward with strong vorticity center at the base already moving across central CA starting to influence sfc to mid-level environment downstream into the Great Basin. Broad areas of DPVA has resulted in a mid-level core of mid-level strato-cu indicating the colder air aloft/steepening lapse rates approaching the area. An associated surface low appear to be developing near LOL/NFL along a tight low level moisture gradient/frontal zone that extends northward into SE OR. Ongoing warm advection/warm conveyor belt with embedded thunderstorms across north-central NV has broadened but also reinforced an effective frontal boundary/pre-frontal trof from N Mineral county, Churchill, central Lander to just NW of Elko.=20 GOES-Visible imagery shows numerous slanted updraft cores developing along its length as southeasterly flow converges and ascends tapping currently limited MUCAPE in the vicinity to allow for further development. This boundary is expected to remain fairly stationary over the next couple of hours, solid insolation to the south should aid the steepening lapse rates for increased instability of 1500 to near 2000 J/kg of CAPE toward the 18z time frame along and south of the boundary. Deep layer steering should allow for cells to reform along the boundary before detaching and lifting north with .5-1"/hr rates. The regenerative nature may allow for localized totals of up to 2". As the stronger forcing approaches, moisture flux will also increase and support stronger updrafts (similar to development currently near Lyon to Douglas counties). Cores will be capable of 1-1.5"/hr rates given deep layer moisture remains at near record values in the .9-1.1" total range. Cells should move quickly enough though and spots of 2-2.25" or possibly higher localized total amounts are possible in a 1-2 hour period, especially near along the effective frontal boundary. Height-falls cooling aloft should eventually dislodge the boundary and propagate it southeastward perhaps toward 21-22z, but this still keeps ample time for some clusters to form with much greater than normal thunderstorm coverage expected. While greatest rates are likely limited to the cores of the updrafts which still may be narrow from a normal perspective, but broader than average in this region. As such, incidents of 2" may be more common but still are likely to be localized and spotty with perhaps a stripe or two existing where training/repeating is best. Still, this is likely to induce localized flash flooding for scattered to numerous coverage across the area of concern (particularly close to the effective boundary axis; though south of the boundary, coverage may be more isolated in nature, but stronger in sub-hourly intensity. Gallina ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!_roRYOKmC9BbzCWB0okwUS6wEcnHfrWawfIDGfRIRWqL834a02Q6Cpp6j6mzCNLjH2i4= Mc70eiN8Cjls35BG9-_v0yQ$ for graphic product... ATTN...WFO...BOI...LKN...REV...VEF... ATTN...RFC...CBRFC...CNRFC...NWRFC...NWC... LAT...LON 42841685 42571556 42161463 41431418 39511410=20 37901479 37411588 37841741 37971821 38151877=20 38641943 39431986 40281991 41001970 41461944=20 42191870 42641804=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) .