Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Mon Jun 05 2023 20:13:54 AWUS01 KWNH 052013 FFGMPD NVZ000-CAZ000-060210- Mesoscale Precipitation Discussion 0433 NWS Weather Prediction Center College Park MD 413 PM EDT Mon Jun 05 2023 Areas affected...Sierra Nevada into northern CA Concerning...Heavy rainfall...Flash flooding possible Valid 052012Z - 060210Z SUMMARY...An isolated flash flood threat is expected through the afternoon into the early evening for the Sierra Nevada and portions of northern CA. Slow moving storms will be capable of 0.5 to 1 inch of rain in 15 minutes with storm totals of 1-2 inches. DISCUSSION...At 20Z, GOES West visible satellite showed an expanding field of TCu as well as a few thunderstorms across the central/northern Sierra Nevada. MLCAPE was estimated to be fairly weak with 500-1000 J/kg on the 19Z SPC mesoanalysis but mostly clear skies between ongoing cloud areas were allowing favorable solar heating at the surface. Moisture values across the region were weakly anomalous with standardized anomalies of PW only near +1, perhaps the greatest limiting factor for flash flooding. Deeper-layer mean flow was approximately 10-20 kt from the southeast for the Sierra Nevada and more easterly in northern CA. An anomalous mid to upper-level closed low was located off of the southern CA coast with a diffluent flow regime aloft and atypical southeasterly to easterly flow at 700 mb in place with speeds ranging from 5 to 20 kt. With continued daytime heating into the afternoon, MLCAPE values up to 1000 J/kg are forecast for the higher terrain with values of 1000-2000 J/kg locally for the northern Sacramento Valley (RAP forecasts). Thunderstorm coverage will continue to increase over the next few hours with sufficient bulk shear in place to support some organized cells. The kinematic pattern in place will favor slow moving storms with a low level upslope component and steering flow quasi-parallel to the axis of the Sierra Nevada. Farther north, shear values are less favorable for organization but easterly flow will favor enhancement into east facing terrain with slightly better instability compared to locations farther south. In addition, a westward moving MCV along the northern CA/NV border may help to focus convection later in the day. While coverage is expected to remain fairly limited, rainfall rates of 0.5 to 1 inch in 15 minutes and 1-2 inch storm totals are expected with the more organized cells that develop. Flash flooding will be possible, but should remain isolated and perhaps most focused on recent burn scar areas. Otto ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!_ZK5M_V135Kts6oKpOdFYA5LpUDFiKOrTFk9wDHYCGqvk8UD3_cgx8ILBTDapXKkdMWX= IgbapbENgaEObKyIVMi7d6Y$ for graphic product... ATTN...WFO...EKA...HNX...MFR...REV...STO...VEF... ATTN...RFC...CNRFC...NWC... LAT...LON 41472233 41212148 40622092 39591988 38811936=20 38291866 37701804 37061769 36591780 36311833=20 36731909 37732016 38522066 39032102 39402135=20 39382189 39282229 39282270 39552289 40122307=20 40662321 41022323 41352295=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) .