####018004963#### ACUS43 KWBC 051506 SCCNS3 Storm Summary Number 1 for West Coast Multi-Hazard Atmospheric River Event NWS Weather Prediction Center College Park MD 700 AM PST Thu Jan 05 2023 ...Heavy rain/snow and high winds batter the West as an atmospheric river flows into the West Coast... Winter Storm Warnings are in effect for portions of the Sierra Nevada. Flood Warnings are in effect for areas of California north of the Bay Area. High Wind Warnings and Wind Advisories are in effect for portions of California and Oregon. Winter Weather Advisories are in effect for the east slopes of the Cascades and areas lee of the Sierra Nevada. Flood Watches are in effect for portions of California west of the Sierra Nevada. For a detailed graphical depiction of the latest watches, warnings and advisories, please see www.weather.gov At 600 AM PST...A low pressure center was analyzed about 300 miles (~500 km) of the coast of Oregon with a minimum pressure of 968 mb (28.59 in Hg). An occluded front extends to the southeast of this low into the Central Valley of California, where there is a triple point. From the triple point, a cold front extends to the south through the Central Valley and into the Pacific Ocean just west of Los Angeles, while a warm front was analyzed over the Sierra Nevada mountains and into portions of the lower Colorado River Valley. Latest surface observations and RADAR show a band of moderate to heavy precipitation accompanied by high winds over much of California. Upslope flow due to westerly winds interacting with the Sierra Nevadas is currently enhancing precipitation west of the mountain range. High winds in combination with the heavy precipitation has contributed many reports of downed trees and closed roads in California. ...Selected preliminary Storm Total Rainfall in inches from 700 AM PST Wed Jan 04 through 600 AM PST Thu Jan 05... ...CALIFORNIA... BURLINGAME 2.0 WSW 2.96 MORAGA 2.4 NNW 2.85 UKIAH MUNICIPAL APT 2.64 K6BPM SANTA BARBARA 2.36 ROHNERT PARK 0.9 SW 2.30 ATASCADERO 2.3 NE 2.13 THOUSAND OAKS 2.1 WSW 2.02 SACRAMENTO INTL APT 1.63 SAN FRANCISCO INTL APT 1.61 LOS ANGELES INTL APT 1.51 HOPLAND 8 SSE 1.50 OXNARD NWS 1.46 SANTA BARBARA MUNICIPAL APT 1.19 ...Selected preliminary Peak Wind gusts in miles per hour earlier in the event... ...CALIFORNIA... KIRKWOOD MEADOWS 1.2 S 119 GRAPEVINE 3 SSE 104 PULGA 2 NNW 102 YORKVILLE 5.5 NW 95 CAPETOWN 6 ENE 94 HIGH GLADE LOOKOUT 89 FERNDALE 6.4 S 88 MAGIC MOUNTAIN TRUCK TRL 87 AMERICAN HOUSE 6 NW 84 AGUA DULCE 8 S 81 MOUNTAIN GATE 3 NNE 72 CRESCENT CITY 1 ESE 69 BLACK MOUNTAIN 7 E 64 The low pressure center associated with this system will move toward the north-northeast as it gradually weakens, with significant impacts anticipated through tomorrow. Maximum rainfall rates over California may exceed 1 inch per hour today, which has been and will continue to result in flooding concerns for the area. Heavy rainfall combined with various burn scars will contribute to an elevated risk for flash flood concerns, especially as it pertains to runoff and streamflows. In addition to the heavy rain, heavy snowfall will continue to impact the Sierra Nevadas, where maximum snowfall may exceed 1-2 feet through Friday. Over time, the impacts from this event will shift toward the north and east as the system disorganizes and dissociates across the eastern Pacific Ocean. Moderate rain and heavy snowfall is expected on Friday over Oregon and Washington, with multiple feet of snow possible in locations higher than 7000 feet. The next Storm Summary will be issued by the Weather Prediction Center at 700 PM PST. Please refer to your local National Weather Service office for additional information on this event. Genz $$