Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sat Nov 15 2025 20:35:59 AWUS01 KWNH 152035 FFGMPD CAZ000-160230- Mesoscale Precipitation Discussion 1226 NWS Weather Prediction Center College Park MD 335 PM EST Sat Nov 15 2025 Areas affected...portions of southern CA Concerning...Heavy rainfall...Flash flooding likely Valid 152033Z - 160230Z SUMMARY...The flash flood threat will continue for coastal CA into the Transverse and Peninsular Ranges through 02Z. While the main/widespread threat of flash flooding is expected to wane over the next couple of hours, a lingering threat for more localized but potentially significant flash flooding will remain. DISCUSSION...Radar mosaic imagery at 20Z showed a band of moderate to heavy rain that extended from the southern San Joaquin Valley into some of the Valley/Desert regions east of the Peninsular Ranges. This axis of heavier rain has been following a plume of highly anomalous moisture translating eastward as seen on OSPO ALPW imagery, out ahead of a negatively tilted mid to upper level shortwave trough axis and vorticity max just west of the CA/MX border. Additional heavy rainfall appeared in the waters just east of Santa Catalina and San Clemente Islands, tied to the eastern lobe of the mid/upper level shortwave. Rainfall over the past 6 hours has peaked near 1 inch for coastal locations into the Peninsular Ranges while 1 to 2+ inch values have been observed within portions of the Transverse Ranges, with hourly rainfall between 0.5 and ~1.0 inches. While relatively drier air was moving into southern CA as of 20Z, the moisture remains anomalous with PW values of ~1.0 to 1.3 inches and despite continued drying of the layer, sufficient moisture will remain through the evening to support localized high rainfall rate potential. As the closed upper low center continues to slowly edge closer to the coast, 700-500 mb lapse rates will increase into the 6.5 to 7.0 C/km range and support localized MLCAPE values in excess of 500 J/kg near the coast. Lift will also be aided by left-exit region divergence/diffluence corresponding to a 100 kt upper level jet max positioned south of the upper low center. Hourly rainfall in the 0.5 to 1.0 inch range is expected, though localized spot training could exceed these values and/or support 0.5 to 1 inch of rain in about 30 minutes. The combination of continued forcing and increased ground sensitivity due to today's rainfall will likely support continued areas of flash flooding over the next few hours. This will especially be true where additional areas of heavy rain overlap with urban areas and burn scars where localized higher impacts could occur. Within sensitive burn scar regions, high rain rates are likely to result in mudslides and debris flows. Otto ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!_j_67JJhFHvq_oLXeomayUqUVfoafWQU8SimSG6NwI_NxuB5p1MdyqdZT-jj6t1orl4x= bP4V2_PJ0kcdmAeJVjLQtOk$ for graphic product... ATTN...WFO...HNX...LOX...SGX...VEF... ATTN...RFC...RSA...NWC... LAT...LON 35541966 35531858 35111811 34381686 33961642=20 33361612 32881611 32461613 32451668 32421710=20 32521739 32741783 33201827 33431858 33891947=20 34462098 35302118=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 3.28-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .