Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Wed Mar 06 2024 22:06:43 AWUS01 KWNH 062206 FFGMPD CAZ000-070405- Mesoscale Precipitation Discussion 0081 NWS Weather Prediction Center College Park MD 505 PM EST Wed Mar 06 2024 Areas affected...Coastal Ranges of Central and Southern CA Concerning...Heavy rainfall...Flash flooding possible Valid 062205Z - 070405Z SUMMARY...A localized threat of runoff problems and flash flooding will exist through this evening across portions of the coastal ranges and interior foothills of central and southern CA from areas of heavy showers. DISCUSSION...The latest GOES-W satellite imagery shows a rather vigorous mid-level shortwave trough and compact area of low pressure offshore of the coastal ranges of central and southern CA advancing gradually off to the east. This energy coupled with the diurnal heating cycle has been fostering the development and expansion of heavy shower activity over the last couple of hours for areas south of the Bay Area, and especially for areas south of Monterey down toward San Luis Obispo and Santa Barbara counties. Steepening mid-level lapse rates coupled with DPVA/forcing aloft and low-level convergence out ahead of the approaching low center and associated front should maintain concerns heading through the late afternoon and early evening hours for locally heavy showers and even a few thunderstorms. MUCAPE values along the coast have risen to as high as 500 J/kg, and this in conjunction with somewhat favorable moisture convergence aligning itself down near the Transverse Range ahead of the surface low should help yield locally heavy rainfall rates that will also have some assistance with orographic ascent over the terrain. The 12Z/18Z HREF guidance shows rather good agreement in seeing some banded convective showers advancing inland over the Transverse Range, and perhaps reaching the Peninsular Range by late this evening. Furthermore, the HREF guidance does show rather high probabilities (50% to 70%) of seeing rainfall rates exceed a 0.50"/hour over the upslope areas of the higher terrain, and already some of the more discrete convective showers farther north in Monterey County have been producing 1 inch totals in less than 30 minutes. Given the current radar and satellite trends, there should be a further increase in coverage of convective showers over the next few hours with heavy rainfall rates. Expect some localized rainfall totals of 1.5 to 2.5 inches to be possible by late this evening where any of the more organized/focused bands of convection set up. This should favor at least some localized runoff concerns with an isolated threat for flash flooding, and the potential for spotty debris flow/mudslide activity. Orrison ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!5e5uYes5bl1g148bla2Y-vfIkTNXe0BaCYm5dSIDOuQckouWS7v3y7IHzy2963NYZ6FR= LQpVwd4iKUAsw-SXoFEQLA0$ for graphic product... ATTN...WFO...HNX...LOX...MTR...SGX...STO... ATTN...RFC...CNRFC...NWC... LAT...LON 37402221 37292130 36692091 35682018 34881935=20 34791879 34401806 33821743 33421716 32861690=20 32591719 32731747 33361798 33801873 34161953=20 34372042 34792081 35212092 35522130 36012172=20 36402202 36732204 37052232=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 3.20-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .