Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Thu Jan 05 2023 10:31:02 AWUS01 KWNH 051030 FFGMPD CAZ000-051600- Mesoscale Precipitation Discussion 0019 NWS Weather Prediction Center College Park MD 530 AM EST Thu Jan 05 2023 Areas affected...southern California Concerning...Heavy rainfall...Flash flooding possible Valid 051027Z - 051600Z Summary...Heavy rain will continue to pose a threat for flooding with possible flash flooding in the vicinity of recent burn scars across areas of higher terrain. Hourly rainfall of 0.5 to 1 inch and 6-hr totals of 2-3 inches are expected through 16Z. Discussion...An axis of heavy rain continued to progress eastward as of 0945Z, located over the Los Angeles metro. Hourly totals have locally peaked in the 0.5 to 0.8 inch range across Santa Barbara and Ventura counties. GPS and satellite derived observations of precipitable water showed values of 1 inch or higher extending from southern San Luis Obispo County to eastern Ventura County. Within this plume of higher moisture, 850 mb winds were in the 40-50 kt range from the south, nearly orthogonal to the orientation of the Transverse Ranges. A limiting factor for higher rainfall totals so far across southern California has been the progressive nature of the band of heavier rainfall. However, RAP analysis soundings indicated shallow instability profiles with 100-200 J/kg CAPE up to 700 mb along the coast and a highly diffluent/divergent flow pattern aloft within the exit region of an upper level jet max located offshore (GOES West derived winds near 100 kt over the coast). While some minor weakening of the axis of low level moisture transport is expected due to peak 850 mb winds lowering about 10 kt, the potential will exist for additional heavy rainfall over the next few hours. Rainfall rates over 0.5 in/hr within the leading edge of the ongoing heavy rainfall plume and additional surges in rainfall intensity will be possible behind the leading axis of heavy rain due to cooling in the low to mid-levels as mid-level heights fall with the eastward advancing closed low/trough off of the West Coast (increasing magnitude of shallow CAPE). Additional peak rainfall totals of 2-3 inches will be possible across the Transverse Ranges with 1-2 inches into the Peninsular Ranges through 16Z. These rains may cause flooding with possible flash flooding/debris flows in the vicinity of recent burns scars. Otto ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!7TkT2_9DtzuB7vmJhyzibTMSEKR9JElj6l6dfkHJo2HbhoOUf8H2Wtb7jj73w1opHBMv= qJ9T6s3et2MeNx1Cu17nEkc$ for graphic product... ATTN...WFO...HNX...LOX...SGX...VEF... ATTN...RFC...CNRFC...NWC... LAT...LON 35492017 35461984 35071926 35021866 34711801=20 34641748 34371683 33991653 33221651 32681636=20 32461650 32461690 32441724 32731742 33071761=20 33371799 33761865 33901918 34241958 34272039=20 34562064 35152055=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) .