Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Wed Mar 22 2023 06:40:38 AWUS01 KWNH 220640 FFGMPD CAZ000-221800- Mesoscale Precipitation Discussion 0117 NWS Weather Prediction Center College Park MD 240 AM EDT Wed Mar 22 2023 Areas affected...Central to Southern CA Coast to Coastal Ranges Concerning...Heavy rainfall Valid 220639Z - 221800Z SUMMARY...Rain showers and an occasional thunderstorm will continue to move ashore the central to southern CA coast over the next 6-12 hours. Additional rainfall of 1-2 inches is expected through 18Z with rates potentially peaking near 0.5 in/hr but with the majority of rates lower near 0.25 in/hr. DISCUSSION...GOES West water vapor imagery at 06Z showed a large, slow moving closed low centered just north of San Francisco Bay with an estimated 120-140 kt upper level jet (GOES DMVs and RAP analysis data) located over southern CA and AZ, southeast of the closed low center. A mid-level vorticity max and associated trough axis were analyzed near 33N 125W, tracking eastward on the south side of the mid-level low center. Scattered showers were noted from near Monterey Bay down into the Los Angeles and San Diego metro areas while steadier rain was falling in the Santa Cruz Mountains with area-wide 700-500 mb lapse rates ranging between 6.5 and 8.0 C/km (00Z VBG/OAK soundings as well as recent RAP analysis data). Recent peak rates have only been 0.1 to 0.3 in/hr, but precipitable water values were only 0.5 to 0.7 inches with weak instability of 500 J/kg or less, supporting occasional thunder. Roughly 1 to 3 inches of rain has fallen over the past 24 hours with scattered reports of flooding from earlier in the day and evening across central to southern CA. Little change to the environment is anticipated over the next 6-12 hours but a gradual weakening of mid-level lapse rates are expected as the mid-upper level low reforms inland along the cyclonic shear side of the upper level jet max through 18Z. W to WSW 850-700 mb flow of 20-30 kt will likely continue from the central to southern CA coast with precipitable water values meandering about the 0.5 to 0.7 inch range. A local increase in shower/thunderstorm activity will be possible along the central CA coast, shifting southward with time ahead of an advancing mid-level vorticity max/trough axis referenced earlier in the discussion. Peak rainfall rates of 0.1 to 0.3 in/hr are likely but localized higher rates cannot be ruled out. An additional 1 to 2 inches of rain are expected through 18Z, with a focus across the higher terrain below snow levels (~4000 ft) along the Coastal Ranges, Transverse Ranges and Peninsular Ranges. Localized flooding cannot be ruled out given antecedent rainfall, but further impacts from flooding are expected to remain localized. Otto ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!5p-KMm9ddJmsTa_fn4LdYkv3u7_fcIAJ9S1HLghdy8siPUDpbTts_qW889DJY2jb8416= 2CqY-z_cBZq_2hnnIktVpzg$ for graphic product... ATTN...WFO...HNX...LOX...MTR...SGX...STO... ATTN...RFC...CNRFC...NWC... LAT...LON 37612197 37502149 37012106 36582066 36182043=20 35822021 35431990 35141971 34921978 34821982=20 34731979 34671974 34651962 34521947 34521933=20 34491907 34631897 34661887 34691876 34671855=20 34631842 34531828 34461824 34421824 34351826=20 34291825 34231815 34181805 34221788 34251782=20 34221773 34211768 34211758 34241748 34241739=20 34211729 34191719 34171709 34121699 34011690=20 33941683 33771677 33591672 33361667 33121661=20 32811650 32521623 32401662 32371709 32681750=20 33301793 33601842 33991954 34302074 35062134=20 35992200 36582249 37132259 37402259 37612232=20 =20=20=20=20=20=20=20=20=20=20=20=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) .