10+ feet (!!) of snow forecast for the Sierra

Well, the current forecast looks good enough here in the Northwest for the next week: cool and showery with snow levels of about 1000-2000 ft.

But it looks totally insane in California, where back-to-back storm cycles of 5-10 ft from Friday-Sunday and 3-6 ft from Monday-Wednesday are predicted for the Sierra Nevada. The first looks to be aimed with maximum amounts south of Tahoe, while the second may strike farther north including Lassen and Shasta. The second system may develop entirely differently than currently forecast (or even fizzle), as numerical weather models are not reliable 4-6 days out, especially following in the wake of a major previous storm.

Here's the NWS winter storm warning for the bullseye of the first system:

[tt]SIERRA NEVADA FROM YOSEMITE TO KINGS CANYON-TULARE COUNTY MOUNTAINS-
558 AM PST FRI DEC 17 2010

A WINTER STORM WARNING ABOVE 7000 FEET REMAINS IN EFFECT FROM 10 AM THIS MORNING TO 4 PM PST SUNDAY FOR THE HIGHER ELEVATIONS OF THE SOUTHERN SIERRA NEVADA.

* SNOW ACCUMULATIONS: 5 TO 10 FEET ABOVE 7000 FEET.

* SNOW LEVELS: WILL RISE AND FALL AT TIMES DURING THIS SERIES OF STORMS...RANGING ANYWHERE
  FROM 6000 FEET TO 8000 FEET... DEPENDING ON THE EXACT TRACK OF EACH INDIVIDUAL SYSTEM.
  HOWEVER THE HEAVIEST SNOW ACCUMULATIONS WILL BE AT AND ABOVE 7000 FEET.
[/tt]

and also for Tahoe:

[tt]URGENT - WINTER WEATHER MESSAGE
NATIONAL WEATHER SERVICE RENO NV
505 AM PST FRI DEC 17 2010

SNOW WILL BEGIN THIS MORNING...WITH THE HEAVIEST SNOW EXPECTED TONIGHT THROUGH EARLY SATURDAY NIGHT...AND AGAIN SATURDAY NIGHT THROUGH SUNDAY. HOURLY SNOWFALL RATES MAY EXCEED 2 TO 4 INCHES PER HOUR DURING THE STRONGEST PORTION OF THE STORM. 3 TO 8 FEET OF SNOW IS LIKELY IN THE SIERRA ABOVE 7000 FEET...WHICH WILL SIGNIFICANTLY INCREASE AVALANCHE DANGER. THOSE LIVING IN REMOTE...HIGHER ELEVATION AREAS IN THE SIERRA COULD BE SNOWED IN FOR MULTIPLE DAYS AND SHOULD PREPARE ACCORDINGLY.

THE SNOW WILL BE VERY HEAVY AND WET WHICH COMBINED WITH THE STRONG...DAMAGING WINDS COULD DOWN POWER LINES AND TREES. THIS MAY CAUSE WIDESPREAD POWER OUTAGES ACROSS THE SIERRA. THE SNOW WILL TURN TO RAIN AT LAKE LEVEL SATURDAY MORNING WITH LOCALIZED POOLING OF WATER LIKELY.
...

GREATER LAKE TAHOE AREA-INCLUDING THE CITIES OF...SOUTH LAKE TAHOE...TRUCKEE...INCLINE VILLAGE
505 AM PST FRI DEC 17 2010

THE WINTER STORM WARNING FOR HEAVY SNOW IS NOW IN EFFECT UNTIL 4 PM PST SUNDAY.

* TIMING: LIGHT SNOW WILL BEGIN THIS MORNING AND CONTINUE THROUGH SUNDAY AFTERNOON.
  PERIODS OF VERY HEAVY SNOW ARE POSSIBLE TONIGHT AND SATURDAY NIGHT INTO SUNDAY.
  SNOW WILL BRIEFLY TURN TO RAIN BELOW 7000 FEET SATURDAY MORNING AND AGAIN SUNDAY MORNING.

* SNOW ACCUMULATIONS: 1 TO 2 FEET IS POSSIBLE AT LAKE LEVEL WITH 3 TO 6 FEET ABOVE 7000 FEET.
  THE HIGHER AMOUNTS WILL OCCUR ALONG THE SIERRA CREST AND ALONG THE WEST SHORE OF LAKE TAHOE.

* SNOW LEVELS: FLUCTUATING BETWEEN LAKE LEVEL AND 7000 FEET.
[/tt]

At least it looks like a wet system with moderately-high snow levels, so that's a small consolation for us in the Northwest.

The standard NWS quantitative precipitation forecast predicts over 14" of precip over the Sierra during the next 5 days (this misses the tail end of the second storm, which would be day 6 from now): www.skimountaineer.com/EquipInfo/Links/Day1-5QPF-JS.html
[img]http://www.skimountaineer.com/TR/Images2010/NWS 5-Day QPF-17Dec2010.gif[/img]

The high-res UW weather model shows the predicted snowfall in each 24-hour period, with maximum snowfall of 3-4 ft in several of those periods:
www.atmos.washington.edu/~ovens/loops/wx...now24+2010121700///3

Thanks for consolidating some of the data.  On the 16th, I started following the thread on Telemarktips and it looks like another storm cycle in The Sierra measured in feet versus inches. Kam should be getting some PNW visitors during the storm cycle.   It's very tempting to head down especially with our season passes around Tahoe.  :'(

Sounds remarkable....but it also sounds like a major mess. Ten feet of heavy, wet snow falling at 4 inches per hour, periodically mixed with rain? Ick.

Today I toured happily in boot top, aerated powder nicely bonded to a firm, wet base. It there'd been another foot or so I'd have been ecstatic. But ten feet? Doesn't matter what it's made of; I can't possibly ski more than the top few feet of it. Anything else has to wait for spring melt.

I bet the LA water district is pleased, however.

Mark

As are those of us Spring Highway 395 vultures.

Here's the Ski Tiger link for CA.

www.skitiger.com/california/

Check the dump at Mammoth 41-57" and still snowing.  Spring touring along hwy 395 in the Eastern Sierra is getting its base. 

Well, the huge storm is now history, and it was a nationally newsworthy event, with up to 17 ft of snowfall in the Sierra, plus record rainfall at lower elevations and severe flooding. The first of the two storm systems (Fri-Sun Dec 17-19) ended up being even stronger and more sustained than the weather models predicted, while the second one (predicted for Dec 20-22) did not end up forming at all in the manner predicted.

Here is the final official NWS storm summary (from www.hpc.ncep.noaa.gov/discussions/nfdscc5.html , but that link will soon be overwritten by other newer storm summaries):

[tt]STORM SUMMARY NUMBER 19 FOR WESTERN U.S. HEAVY PRECIPITATION EVENT
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
700 AM PST THU DEC 23 2010


...SELECTED STORM TOTAL SNOWFALL IN INCHES WHERE THE EVENT HAS
ENDED...

...CALIFORNIA...
PASCOES SNOTEL                       204.0 ESTIMATED           
WEST WOODCHUCK MEADOW                192.0 ESTIMATED           
WET MEADOWS SNOTEL                   191.0 ESTIMATED           
KAISER POINT SNOTEL                  168.0 ESTIMATED           
CRABTREE MEADOW SNOTEL               143.0 ESTIMATED           
MAMMOTH LAKES 3 WSW                  108.0                     
MAMMOTH MOUNTAIN TOP                 108.0 TO 162             
NORTHSTAR                            98.0                     
ASPENDELL 1 WNW                      74.0                     
LONE PINE 10 SW                      72.3                     
JUNE MOUNTAIN                        69.0                     
ALPINE MEADOWS                       67.0                     
SQUAW VALLEY                         57.0                     
HOMEWOOD                             55.0                     
KIRKWOOD SKI AREA                    52.0                     
JUNE LAKE                            48.0                     
TRUCKEE 2 W                          42.0                     
LEE VINING 5.9 NW                    34.6                     
BLACKCAP BASIN                       33.0                     
CHARLOTTE LAKE                       30.0                     

...IDAHO...
KETCHUM 22 NW                        22.0                     
PRESTON 20 NE                        18.5                     
HAILEY 20 ENE                        18.0                     

...NEVADA...
HEAVENLY VALLEY                      77.0                     
MOUNT ROSE                           65.0                     
GREAT BASIN NATIONAL PARK 5 W        31.0                     
INCLINE VILLAGE 1 NE                 31.0                     
WHEELER PEAK                         31.0                     
MT. CHARLESTON 4 WNW                 26.0                     
ELY 9 SSW                            23.0                     
MCGILL 10 ESE                        19.0                     
RENO 9 W                             17.0                     
RUTH                                 16.1                     
CARSON CITY 1.3 NW                   12.0                     

...OREGON...
THREE RIVERS 0.7 NNE                 12.7                     
ADEL 19.4 ESE                        12.0                     
BAKER 0.6 ENE                        11.2                     
TERREBONNE 9.4 NW                    10.5                     
MADRAS 6.6 NNW                       10.2                     
WSW CAMP SHERMAN                      9.0                     
HOOD RIVER                            8.0                     
SUNRIVER                              8.0                     
TIMBERLINE LODGE                      8.0                     
WILSON RIVER SUMMIT                   8.0                     
TUMALO 9 NW                           7.0                     
WILLAMEETTE PASS                      7.0                     

...SELECTED STORM TOTAL RAINFALL IN INCHES WHERE THE EVENT HAS
ENDED...
...A PORTION OR ALL OF THE PRECIPITATION AT SOME OF THESE SITES
MAY HAVE FALLEN AS SNOW...

...CALIFORNIA...
CRESTLINE 0.2 WSW                    26.16                     
TANBARK                              19.22                     
WISHON DAM                           18.89                     
CAMP NELSON 6SW                      18.60                     
NATURE POINT NEAR BASS LAKE          18.60                     
WOFFORD HEIGHTS                      15.78                     
DEVORE                               15.62                     
LYTLE CREEK 2 SSE                    15.03                     
WRIGHTWOOD 1.2 WNW                   14.24                     
SANTA BARBARA 1.9 NE                 14.23                     
SAN BERNARDINO 5N                    12.41                     
LOS ANGELES-USC                       8.13                     
OXNARD AIRPORT                        7.21                     
SANTA BARBARA MUNI ARPT               6.35                     
SAN DIEGO/MONTGOMERY FIELD            5.36                     
SAN FRANCISCO INTL ARPT               3.28                     

...NEVADA...
MOUNT CHARLESTON                     13.46                     
GARDEN SPRING                         9.71                     
LAS VEGAS 24 WNW                      8.99                     
WARD MOUNTAIN SNOTEL                  5.80                     
MOUNTAIN SPRINGS                      5.45                     
RUTH                                  5.21                     
MERCURY/DESERT ROCK ARPT              4.31                     
PIOCHE                                4.23                     
RED ROCK CANYON                       3.08                     
GARDNERVILLE 5 W                      2.95                     
RENO 5.6 WSW                          2.59                     
CARSON CITY 1.5 ENE                   2.27                     
NORTH LAS VEGAS AIRPORT               1.84                     

...OREGON...
PORT ORFORD 5 E                       5.33                     
CAVE JUNCTION 3.7 E                   4.86                     
BROOKINGS 4.2 ENE                     4.85                     
SEXTON SUMMIT                         4.28                     
ROGUE RIVER 6 N                       3.81                     
GOLD BEACH 4.8 NE                     3.43                     
WILLIAMS 1 N                          2.75                     


...SELECTED STORM TOTAL SNOWFALL IN INCHES FROM 700 PM PST FRI DEC
17 THROUGH 700 AM PST THU DEC 23...

...COLORADO...
GOTHIC                               82.0                     
CRESTED BUTTE 6.2 N                  77.5                     
COAL BANK PASS                       48.0                     
RED MOUNTAIN PASS                    44.5                     
MOLAS PASS                           41.0                     
SILVERTHRONE 10 E                    32.0                     
DILLON 9 E                           29.0                     
BRECKENRIDGE 2 W                     28.0                     
WALDEN 16.3 WSW                      23.5                     
COPPER MOUNTAIN                      23.0                     
STEAMBOAT SPRINGS 1 SE               20.2                     
WOLF CREEK PASS 1 E                  18.0                     
VAIL 2.6 E                           14.4                     

...UTAH...
BRIGHTON CREST                       84.0                     
DEER VALLEY DALY WEST                76.0                     
ALTA - COLLINS                       69.0                     
PROVO CANYON                         68.0                     
ALTA UDOT                            67.0                     
SOLITUDE                             54.0                     
SNOWBIRD                             50.0                     
PARK CITY JUPITER PEAK               43.0                     
SNOWBASIN MID BOWL                   43.0                     
THE CANYONS                          36.0                     
SALT LAKE CITY 3.6 SE                 5.4                     

...WASHINGTON...
LEAVENWORTH 1 NNW                    12.4                     
PESHASTIN 5.3 SSW                     7.8                     
HUSUM 1.8 NE                          7.6                     
CARSON                                7.0                     

...WYOMING...
OLD BATTLE                           73.5                     
SKYLINE 8 SW                         63.0                     
BROOKLYN LAKE                        60.0                     
WEBBER SPRINGS                       58.5                     
NORTH FRENCH CREEK                   57.0                     
LITTLE SNAKE RIVER                   50.4                     
SAND LAKE                            48.0                     
DIVIDE PEAK                          36.0                     
NORTH SAND LAKE                      34.5                     
ROB ROY RESERVOIR 2 NE               33.6                     

...SELECTED STORM TOTAL RAINFALL IN INCHES FROM 700 PM PST FRI DEC
17 THROUGH 700 AM PST THU DEC 23...
...A PORTION OR ALL OF THE PRECIPITATION AT SOME OF THESE SITES
MAY HAVE FALLEN AS SNOW...

...ARIZONA...
BLACK ROCK RAWS                      11.59                     
IRON SPRING                          11.14                     
CEDAR HILLS                           7.04                     
NIXON FLATS RAWS                      6.52                     
CHLORIDE 3 ESE                        6.41                     
TWEED POINT                           5.70                     
KINGMAN 12 SE                         3.86                     
GRAND CANYON WEST                     3.15                     
BULLHEAD CITY 3.8 NE                  2.61                     
FLAGSTAFF PULLIAM AP                  1.99                     
GRAND CANYON NATIONAL PARK            1.51                     

...UTAH...
GUTZ PEAK                            18.70                     
LITTLE GRASSY                        17.50                     
KOLOB                                11.10                     
LAVA POINT RAWS                      10.79                     
MIDWAY VALLEY                        10.10                     
BIG FLAT                              8.70                     
TIMPANOGOS DIVIDE                     8.70                     
HARRIS FLAT                           8.50                     
SOLITUDE                              8.35                     
BEN LOMOND TRAIL                      8.30                     
LONG VALLEY JCT                       8.30                     
SALT LAKE CITY INTL ARPT              1.97                     

...WASHINGTON...
PESHASTIN 0.7 NE                      5.18                     
OCEAN SHORES 1.2 NNW                  2.07                     

THE LAST OF A SERIES OF MOIST PACIFIC SYSTEMS WILL MOVE EASTWARD
AND OUT OF THE DESERT SOUTHWEST ON THURSDAY. ADDITIONAL RAINFALL
AMOUNTS THROUGH FRIDAY MORNING WILL GENERALLY BE LESS THAN AN INCH
AT MOST LOCATIONS. AT THE HIGHER ELEVATIONS...AN ADDITIONAL 2 TO 4
INCHES OF SNOW...WITH LOCALLY HIGHER AMOUNTS...WILL BE POSSIBLE
THROUGH FRIDAY MORNING...MAINLY ACROSS THE COLORADO ROCKIES.
PRECIPITATION SHOULD COME TO AND END FROM WEST TO EAST ACROSS THE
DESERT SOUTHWEST INTO THE INTERMOUNTAIN WEST ON THURSDAY AS HIGH
PRESSURE BUILDS INTO THE REGION.

THIS WILL BE THE LAST STORM SUMMARY ISSUED BY THE
HYDROMETEOROLOGICAL PREDICTION CENTER FOR THIS EVENT. PLEASE REFER
TO YOUR LOCAL NATIONAL WEATHER SERVICE OFFICE FOR ADDITIONAL
INFORMATION.
[/tt]