Subj : MESO: Mesoscale Discussion 2074 To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Fri Sep 01 2023 19:32:00 ACUS11 KWNS 011931 SWOMCD SPC MCD 011931=20 AZZ000-NVZ000-CAZ000-012200- Mesoscale Discussion 2074 NWS Storm Prediction Center Norman OK 0231 PM CDT Fri Sep 01 2023 Areas affected...Portions of the Lower CO River Valley and southeastern CA Concerning...Severe potential...Watch unlikely=20 Valid 011931Z - 012200Z Probability of Watch Issuance...20 percent SUMMARY...Thunderstorms should gradually increase in coverage and intensity through the afternoon. Locally severe gusts and marginally severe hail are possible with the stronger storms. DISCUSSION...Cloud clearing/thinning in the wake of morning convection is yielding ample diurnal heating/destabilization of a moist air mass (1.5+ inch PW and middle/upper 60s to lower 70s surface dewpoints) over portions of the Lower CO River Valley and southeastern CA. At the same time, midlevel ascent peripheral to a large-scale mid/upper-level low over the Northwest will support steepening midlevel lapse rates atop the destabilizing boundary layer. In the near-term, a cluster of thunderstorms will continue evolving north-northwestward along an outflow boundary in southwestern AZ. While modest deep-layer shear (around 20 kt of 0-6 km bulk shear per regional VWP data) could favor outflow-dominant storms, moderate surface-based instability -- characterized by deep/rich moisture and diurnally steepening low-level lapse rates -- will support strong to locally severe gusts and sporadic hail. Through the remainder of the afternoon, additional thunderstorm development (possibly outflow dominant with southward extent) is expected along terrain features and differential heating zones -- aided by the glancing large-scale ascent. Minimal convective inhibition and the aforementioned rich/deep moisture should promote numerous thunderstorms and related cell interactions/mergers. Strong to severe gusts are the main concern with any clusters that develop in this environment, though marginally severe hail cannot be ruled out with the more-separated updrafts. As storms develop/spread northward into southern NV -- where a belt of stronger midlevel southwesterlies and related deep-layer shear is in place -- increasingly organized storm structures (including transient/embedded supercells and clusters) could evolve. However, this will be dependent on the degree of surface-based heating/destabilization, which will generally be maximized over areas farther south. ...Weinman/Mosier.. 09/01/2023 ....Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!6M_jpIb3vlsMgfTGSheHam48iDg27vA9R_jC-tY6JUL5eyyCVc6SP9c4zWCUQ63HAItLcDrgb= 1xrpFq3-q4NSHilSYk$ for graphic product... ATTN...WFO...PSR...VEF...SGX... LAT...LON 32481508 32591591 32691602 33371619 34431634 35301642 36341650 36871643 37201627 37341587 37281533 37021458 36481417 34951382 34251379 33541369 33041372 32451387 32221408 32481508=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) .