Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sun Feb 18 2024 21:30:17 AWUS01 KWNH 182130 FFGMPD CAZ000-190328- Mesoscale Precipitation Discussion 0062 NWS Weather Prediction Center College Park MD 429 PM EST Sun Feb 18 2024 Areas affected...northwestern and portions of central California Concerning...Heavy rainfall...Flash flooding possible Valid 182128Z - 190328Z Summary...Increasing coverage of moderate to heavy rainfall is expected across the discussion area through the afternoon and early evening. Areas of 0.5 inch/hr rain rates are expected, potentially causing a few areas of excessive runoff. Discussion...Water vapor and radar mosaic imagery indicates the presence of a few areas of rainfall beginning to approach coastal areas near/just south of Eureka as of 2110Z. A separate area of lighter rainfall was located near/west of San Francisco and vicinity. The rainfall was increasing in coverage and being forced by difluence aloft and the slow approach of a larger upper wave over the Pacific centered near 38, -134. Additionally, low-level wind fields were beginning to increase dramatically along coastal areas in tandem with the approach/eastward translation of a 50-kt 850 mb jet. Rainfall rates were generally light over the past hour (0.1-0.15 inch/hr), although the eastward translation of the aforementioned synoptic features, increased orographic ascent, and slow cooling aloft/mid-level destabilization should result in rain rates increasing into the 0.25-0.5 inch/hr range - especially during the 00Z-03Z timeframe. As rain rates increase in tandem with a more active convective pattern, areas of excess runoff will become more likely. The greatest concern for flash flooding will reside generally from the northern coastal ranges (from San Francisco Metro northward) and windward slopes of the Klamath Mountains below the freezing level. Orientation of southeasterly 850mb flow relative to terrain in these areas will likely support local enhancement of rain rates and excessive runoff potential especially in low/sensitive spots.=20 The risk will likely extend beyond 0330Z, and an updated MPD may be needed pending rainfall and convective trends around that time. Cook ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!-D5VAbb6HBa2Zyz9faZn6fwLhecFiY0m5cIR-zW1hKq-W2v0_JGYHcEYF8GviYdOdUIf= U1mM59H4UrO3ZIJtAFhRpOw$ for graphic product... ATTN...WFO...EKA...MFR...MTR...REV...STO... ATTN...RFC...CNRFC...NWC... LAT...LON 41942291 41292112 39972087 38532119 37392211=20 37832294 39932419 41402422=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) .