Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue Jan 10 2023 09:12:03 AWUS01 KWNH 100911 FFGMPD CAZ000-101745- Mesoscale Precipitation Discussion 0036 NWS Weather Prediction Center College Park MD 411 AM EST Tue Jan 10 2023 Areas affected...Transverse Ranges into northern Peninsular Ranges of southern CA Concerning...Heavy rainfall...Flash flooding likely Valid 100910Z - 101745Z Summary...A prolonged period of moderate to heavy rain is likely for the Transverse Ranges into the northern Peninsular Ranges of southern CA. Rainfall rates will occasionally peak in the 0.5 to 0.8 in/hr range with additional totals of 2-5 inches through 18Z. Continued areas of life threatening flooding/flash flooding can be expected. Discussion...08Z TPW imagery and GPS sensors along the coast showed two plumes of relatively higher precipitable water pointed toward the central and southern coast of CA. The leading moisture axis was located from Ventura County to northern San Diego County with values of 0.9 to 1.1 inches, associated with a dissipating cold front. A secondary moisture axis with PW values of 0.9 to about 1 inch was tied to a strengthening cyclone approaching the north-central coast of CA. The leading moisture axis has been weakening over the past few hours but rainfall rates of 0.5 to 1 in/hr have continued over portions of Los Angeles County from near and northeast of downtown into the San Gabriel Mountains where 30 to 45 kt of 850-700 mb winds remained as of 08Z. The secondary moisture axis was disconnected from the leading moisture axis but still tied to an area of strong ascent ahead of an approaching negatively tilted mid to upper-level trough axis offshore of the northern CA coastline. An estimated 150kt (GOES DMVs) to 180 kt (RAP analysis) upper level jet was located on the west side of the negatively tilted trough as of 08Z. Rainfall rates of 0.5+ in/hr are expected to continue in favored south facing slopes of the Transverse Ranges for the next 2-4 hours with a brief lull in rainfall intensity afterward. However, the approach of the secondary moisture axis and a surge in lift tied to the left exit region of the powerful jet mentioned above should support a renewed round of heavy rain with rainfall rates again peaking over 0.5 in/hr, starting in San Luis Obispo and Santa Barbara Counties between 15-17Z. Numerous reports of flooding, flash flooding and debris flows have occurred in and around the Transverse Ranges over the past 6-12 hours from as much as 10-16 inches of rain over the past 24 hours. Both creeks and larger stem rivers are in flood stage with saturated soils in place. The addition of 2 to as much as 5 more inches of rain is forecast for the favored upslope of the Transverse Ranges through 18Z, with continued flooding/flash flooding likely. Otto ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!9jP6MIp6mSzSJgE7yWnt1rS8nkmViVmQXye4zwrHnNyubz9DmPki8fisI1ohpq_3QB3X= Zp0TTGP3afKgIRkqdFlvYaY$ for graphic product... ATTN...WFO...HNX...LOX...SGX... ATTN...RFC...CNRFC...NWC... LAT...LON 35482018 35391975 34831883 34781827 34521778=20 34291686 33701658 33211680 33271757 33521835=20 33931926 34161973 34282048 34552081 35232072=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) .