Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue Mar 28 2023 17:03:41 AWUS01 KWNH 281703 FFGMPD CAZ000-290500- Mesoscale Precipitation Discussion 0145 NWS Weather Prediction Center College Park MD 101 PM EDT Tue Mar 28 2023 Areas affected...California Concerning...Heavy rainfall Valid 281700Z - 290500Z SUMMARY...Modest atmospheric river activity to continue across California today and going through the evening hours. Additional heavy rains are expected and this may foster some localized runoff concerns. DISCUSSION...The latest GOES-W IR/WV suite shows a strong deep layer closed low offshore of northern CA that continues to transport Pacific moisture eastward along and ahead of a well-defined cold front. The axis of strongest moisture transport with IVT values of 500 to 600 kg/m/s continues to gradually settle southward down the coast, and radar imagery shows heavy rains beginning to overspread the coastal ranges near and to the north of the Bay Area, but also even into the interior valleys of the northern Sacramento Valley. Rainfall rates over the last few hours have been as high as 0.25" to 0.50"/hour over the northern CA coastal ranges, and these rates will be overspreading the Bay Area over the next few hours. The PWs across the region are forecast to rise this afternoon to as much as 1.5 to 2 standard deviations above normal just ahead of the front, and this may favor some rainfall rates getting over a 0.50"/hour and especially for areas farther down the coast towards Monterey and including the Santa Cruz mountains with considerations of stronger upslope flow and forcing with the front. The 12Z HREF guidance does show some low-end probabilities of seeing 0.50+"/hour rainfall rates ovespreading far eastern areas of the Central Valley and the foothills of the northern and eventually central Sierra Nevada below the snow level as the corridor of stronger IVT and related warm air advection advances farther south and east. Expect additional rainfall amounts locally of as much as 2 to 3 inches going through this afternoon and evening, with isolated heavier amounts. These heavier amounts will be mostly confined to the coastal ranges and the foothills of the Sierra Nevada. Some runoff problems and localized flooding concerns cannot be ruled out based on the storm totals. Orrison ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!-_ZEJxI7_KdM9tyfH3UeHVO0ph50m9KGd87owEx-_d6H1UAsS_CSd42VeDo896HL4g23= HwpZNF8uFy6xOCXKQcmIvhw$ for graphic product... ATTN...WFO...EKA...HNX...LOX...MTR...STO... ATTN...RFC...CNRFC...NWC... LAT...LON 40942212 40632178 39872151 39032070 37842000=20 37251950 36781944 36181954 35861969 35631992=20 35292029 35222088 36182187 37322274 37992293=20 38392325 39212384 39562392 39952393 40442385=20 40592359 40802312 40912270=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) .