Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sat Jan 14 2023 19:53:29 AWUS01 KWNH 141953 FFGMPD CAZ000-142230- Mesoscale Precipitation Discussion 0041...Corrected NWS Weather Prediction Center College Park MD 252 PM EST Sat Jan 14 2023 Corrected for Summary Context Areas affected...Northern and Central CA Concerning...Heavy rainfall...Flash flooding possible Valid 141500Z - 142230Z SUMMARY...Heavy rains will continue to overspread northern and central CA today as the next in a series of West Coast storms systems arrives. This will facilitate areas of flooding, and potentially localized flash flooding given the wet/saturated soil conditions. DISCUSSION...Surface observations and satellite imagery show a strong storm system offshore of the the West Coast continuing to advance east which is driving a cold front toward the coastal ranges of central and northern CA. A southwest low-level jet of 40 to 50 kts ahead of the front is favoring strong warm air advection and moisture transport into the coastal terrain and inland across the interior valleys and foothills of the Sierra Nevada. Already ongoing IVT values of as much as 500 to 700 kg/m/s with an orientation largely orthogonal to the terrain is fostering widespread heavy rainfall with rates across the coastal ranges north and south of the Bay Area in the 0.25" to 0.50" range. Radar imagery shows heavier rains also becoming increasingly noted across portions of the Sacramento Valley as these higher IVT values punch inland with the low-level jet. The Bay Area should tend to be the focus for the heaviest rains over the next few hours along with the adjacent coastal ranges. However, increasing IVT values and forcing will spread farther down the coast, and especially with an emphasis on Monterey, San Luis Obispo, and Santa Barbara counties going through 21Z. From the Bay Area south down across the Santa Cruz, Santa Lucia, and eventually the Santa Ynez mountain mountains, rainfall rates should increase to locally around 0.75"/hour. Similar rates are expected to impact the foothills of the Sierra Nevada east of the Central Valley as well, and all of these rains today are expected to foster additional runoff and flooding concerns giving the very wet/saturated antecedent conditions. Some localized flash flooding will be possible with some of these rates where they overlap with some of the area burn scar locations. Gradually the offshore cold front will edge inland going through the afternoon hours, and this will allow for the rains to begin to become more showery in nature for northern CA, but areas farther south closer to the Transverse Range will continue to see rains along and ahead of the front lasting for much of the day. Orrison ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!4xyPGzKy_ifJIpARePBq-Dct7QVs3hGnRkIz3m5tGUoKc63tVXiHgjsaLEsep-6zMfJ4= 7zcIaWHtsAcqfc-dvakjnBI$ for graphic product... ATTN...WFO...EKA...HNX...LOX...MFR...MTR...REV...STO... ATTN...RFC...CNRFC...NWC... LAT...LON 41522338 41112240 40442162 39032058 37741913=20 36771853 36481920 37322042 37422081 37052115=20 35872077 35001970 34511937 34221985 34182037=20 34522071 35582134 36902235 38042310 38962390=20 40202445 41272427=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) .