Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Mon Feb 05 2024 08:42:39 AWUS01 KWNH 050842 FFGMPD CAZ000-051800- Mesoscale Precipitation Discussion 0049 NWS Weather Prediction Center College Park MD 342 AM EST Mon Feb 05 2024 Areas affected...Southern California... Concerning...Heavy rainfall...Flash flooding likely Valid 050900Z - 051800Z SUMMARY...Core of Atmospheric River stalling over Southern California. While intensity of moisture flux, rainfall rates will be reducing through the early morning; prolonged moderate rainfall will support an additional 1-4" through 18z and likely to continue considerable flash flooding, mud & landslide conditions. DISCUSSION...GOES-W WV depicts the main upper low continuing to swirl along the NW CA/SW ORE coastline with 985mb surface low starting to show signs of filling. As both lift north, broadening mid-level dry slot is expanding over the Central California coast and broadening the sfc to 850 pressure/height gradient reducing the strength of the winds across the California Bight. CIRA LPW also denotes the sfc-850mb moisture stream is narrowing and pinching a bit through the Channel Islands toward Orange county; though 850-700mb moisture stream remains fairly broad and within confluent flow of 40-55kts through the region. As such, limited height-falls and perhaps weak shortwave height-rises have been noted and forward propagation of the warm conveyor belt has begun to stall. A few more hours of 25-30kts of south-southeasterly flow along/ahead of the cold front will continue to support maximized moisture convergence with embedded vertical development along the leading edge. Narrow bands of ..25-.5"/hr rates can be seen through the Bight into Southern LA county, Orange county and starting to enter NW San Diego county.=20 These cells will become more wavy and diffuse with time and reduce to below .25"/hr by morning. This diffusion should allow for broadening of the plume bringing back lighter but still up to ..25"/hr into Ventura/western LA county after 12z, resulting in an additional 1-3" by 18z.=20 However, southwesterly flow through depth will continue to ascend favorably through the Santa Ana, eastern San Gabriel and into the San Bernadino Ranges and perhaps the northern portions of the San Jacinto Range. Rates of .5" to .75"/hr will reduce to .33-.5"/hr after 12-15z but still support 2-5" of additional rain. This will continue/maintain the risk of flash flooding and mud slides across the Hollywood Hills across into the San Gabriel Range, likely to expand into the Santa Ana and San Bernardino Range...though given reduced rates, the rise may be a tad slower than experienced further west, still this flooding will be dangerous and life-threatening through Monday morning. Gallina ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!_9Br5_VIf7lynjRki3zlW5gtif-C5zNI7EmyvdlKZB8kODGShvB2PUrIN1TGAbF4GgCz= RWMgGc4IrjCIT-0DrDqd-Wk$ for graphic product... ATTN...WFO...LOX...SGX... ATTN...RFC...CNRFC...NWC... LAT...LON 34771897 34701812 34521742 34291683 33851661=20 33461665 32931697 32621758 32711839 33011884=20 33511905 34011916 34301933 34601933=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) .