A series of storms attributed to an atmospheric river event (AR) will continue to produce heavy mountain snow and strong winds across the northwestern U. S. through the weekend. On average, about 30-50% of annual precipitation in the west coast states occurs in just a few atmospheric river events. This is one of them.
Atmospheric Rivers (AR) are relatively narrow regions in the atmosphere that are responsible for most of the horizontal transport of water vapor outside of the tropics. While ARs come in many shapes and sizes, those that contain the largest amounts of water vapor, the strongest winds, and stall over watersheds vulnerable to flooding, can create extreme rainfall and floods. These events can disrupt travel, induce mud slides, and cause catastrophic damage to life and property. However, not all ARs cause damage – most are weak, and simply provide beneficial rain or snow that is crucial to water supply
Many of the higher elevation in the west will measure snowfall totals in feet this week.
“The snow could accumulate a couple of feet in the highest peaks of the central Sierra, the part of the range that needs mountain snow the most for ski resorts and water resources,” AccuWeather Meteorologist Brian Lada said.
WINTER STORM WARNING for CALIFORNIA:
URGENT – WINTER WEATHER MESSAGE
…WINTER STORM WARNING REMAINS IN EFFECT FROM 4 AM THURSDAY TO 4 AM PST FRIDAY…
* TIMING: SNOW WILL MOVE INTO THE LAKE TAHOE BASIN LATE TONIGHT WITH HEAVY SNOWFALL BY THURSDAY MORNING. SNOW WILL DECREASE BY THURSDAY EVENING WITH SNOW SHOWERS LINGERING INTO FRIDAY MORNING.
* SNOW ACCUMULATIONS: ABOVE 7000 FEET…1 TO 2 FEET WITH LOCALLY UP TO 3 FEET NEAR THE SIERRA CREST. BELOW 7000 FEET…7 TO 14 INCHES EXCEPT 12 TO 18 INCHES WEST OF HIGHWAY 89.
* WINDS: STRONG WINDS ARE EXPECTED TONIGHT INTO THURSDAY MORNING.SOUTHWEST 30 TO 45 MPH WITH GUSTS UP TO 65 MPH.RIDGE GUSTS UP TO 125 MPH. DAMAGE TO TREES IS POSSIBLE.
* SNOW LEVELS: 8000 TO 8500 FEET TONIGHT…THEN FALLING TO BELOW 5500 FEET BY EARLY THURSDAY AFTERNOON.
* IMPACTS: SNOW AND BLOWING SNOW WITH WHITEOUT CONDITIONS AND ICY ROADS. SNOWFALL RATES WILL EXCEED PLOWING CAPABILITIES AT TIMES. THIS INCLUDES INTERSTATE 80…HIGHWAY 50…CALIFORNIA HIGHWAYS 88…89…267 AND NEVADA HIGHWAYS 28…207 AND 431. SIGNIFICANT DELAYS AND DANGEROUS WINTER WEATHER CONDITIONS POSSIBLE FOR BACK COUNTRY ACTIVITIES.