Tahoe Precip?

[ryank]

The Wood was definitely decent over the weekend if you like shredding groomers. I did some lines off the Wall and they were pretty good in the afternoon after the snow had a chance to soften up.

Coverage is still decent, but south facing stuff is starting to hurt - Flying Carpet and Juniper off Caples Crest were getting bare.

Everything off Sunrise was fine, just somewhat boilerplate.

I don't know how Sentinel was, as I didn't go to skier's left of the Corny Express.

[basom]

THE MODELS/ENSEMBLES CONTINUE TO SUPPORT A GULF OF ALASKA/EASTERN
PACIFIC LOW PRESSURE SYSTEM THAT DIRECTS A MOIST SOUTHWEST FLOW OVER
CA AND WESTERN NV THROUGH THE EXTENDED PERIOD. SUBTROPICAL MOISTURE
IN THIS FLOW WILL PROVIDE SIGNIFICANT PRECIPITATION TOTALS AND HIGH
SNOW LEVELS FOR THE SIERRA AND NORTHEAST CA. THE GFS IS SHOWING 6
INCHES OR MORE OF WATER EQUIVALENT ON THE WEST SLOPES OF THE SIERRA
MAINLY NORTH OF MONO COUNTY

[woodsskier]

T-boz, I was out scouting lines in C2 yesterday...snow still held up, airtemps didn't warm enough to change the snow on North North east facing....C2 looks to be in good shape actually....should be fun next week, looks like we'll get the bonus of thsi torm too...6" of water!!!! All snow above 7k......we'll see.

[Sierra Cement]

THE GFS IS SHOWING 6
INCHES OR MORE OF WATER EQUIVALENT ON THE WEST SLOPES OF THE SIERRA
MAINLY NORTH OF MONO COUNTY

This could be like the New Years flood of '97.....if there was more snow to melt and runoff. This looks like it may wash away the lower elevation snow of all the resorts. Pray it comes in cold my brother!

[skimoore]

This could be like the New Years flood of '97.....if there was more snow to melt and runoff. This looks like it may wash away the lower elevation snow of all the resorts. Pray it comes in cold my brother!

Even if it rains, Kirkwood will still guaaaareeennntteeeee the best snow/dirt in Tahoe.

[skiski]

6 inches. holy shit. you guys will either be rolling in it, or making plans for next season. out of curiosity, what are the general top and bottom elevations in the tahoe area (i haven't skied there since i was a kid).

[Cirquerider]

With the forecast for 6-inches (liquid equivalent) of precipitation through the weekend, snowfall could be very impressive, and just what is needed to finally cover the rocks, spines and chutes. Especially if winds don't go crazy high like with the last storms. So 3 to 6 feet of snow could make a difference in anyone's ski season. A 7000 foot elevation is pretty dicey for some ski area bases that are below 6500 feet, especially Sierra, Homewood, and Northstar. Higher base elevations of Rose (7800 ft), Kirkwood (7800 ft), and the upper lifts at Heavenly, Alpine, Sugar Bowl and Squaw stand to benefit.

With things so dry, and no low elevation snowpack flooding is not much of a risk. The 97 floods came on the heels of an abundant wet snowfall up to 4-5 feet down to the 4000 foot elevation, followed by days of rain to the summit.

Looks like sloppy seconds for Utah on this system with the remnants of the ridge still holding out some of the moisture.

[The Dad]

Elevations vary, obviously. Squaw's base is 6200', Alpine's is 6800' and change.

And what Cirque said.

[mmcpheet]

This could be like the New Years flood of '97.....if there was more snow to melt and runoff. This looks like it may wash away the lower elevation snow of all the resorts. Pray it comes in cold my brother!

An article about rain on snow events from CA DWR Division of Flood Management.

Interesting how neither the depth nor water content of the snowpack are factors in the snowmelt runoff equation:

Rain on Snow

When rain falls on ripe snow, the water itself doesn't cause snow to disappear; however, the accompanying warm air temperature increases the melt rate. What impact does rain actually have on the snowpack?

According to the Corps of Engineers' Snow Hydrology manual,

Mr = 0.00695 (Tr - 32) Pr

where Mr is the melt, in inches of water, Tr is the mean rain temperature (F), and Pr is the inches of rainfall. Therefore, it would take about 10 inches of rain at 48F to melt one inch of snow water content.

Much of work to develop and verify this equation was done at the Central Sierra Snow Laboratory located at Soda Springs near Donner Summit. Considerable work remains to refine the physical mechanisms of how the rain water migrates through the pack.

Only after prolonged, warm rainfall will snowmelt be a major contributor to runoff. This did occur in February, 1986 and during the first week of 1997. Dense snow makes shovelling difficult and leaves abundant "Sierra cement" on the ski slopes.

[Ubersheist]

Even the Sacramento NOAA office is giving this next change a very positive spin:

THE PERSISTENT DRY WEATHER PATTERN OVER NORTHERN CALIFORNIA IS
EXPECTED TO END LATER THIS WEEK. A POWERFUL PACIFIC JET STREAM
WILL FINALLY PUNCH THROUGH THE UNUSUALLY STRONG HIGH PRESSURE
RIDGE THAT HAS KEPT THE AREA DRY FOR SO LONG. THE JET STREAM WILL
TAP INTO A DEEP SUBTROPICAL MOISTURE PLUME AND AIM IT RIGHT AT
CALIFORNIA...BEGINNING WEDNESDAY...AND PERSISTING INTO THE WEEKEND.

SEVERAL INCHES OF LIQUID PRECIPITATION AND SIGNIFICANT SNOWFALL
ARE EXPECTED...ESPECIALLY FROM THURSDAY INTO THE WEEKEND...OVER
NORTHERN CALIFORNIA. THE UPCOMING WET WEATHER COULD MAKE A
SIGNIFICANT RECOVERY IN THE PRECIPITATION DEFICIT OVER NORTHERN
CALIFORNIA...AND TURN THIS MONTH INTO A...FABULOUS FEBRUARY.

"Fabulous," eh? Hmm....

[The Dad]

Looking at NOAA further and parsing the info, comparing the discussion with the forecast....

BY AROUND 18Z WEDNESDAY THE FIRST SHORTWAVE ASSOCIATED WITH THIS SYSTEM SHOULD BE MOVING THROUGH NRN CALIFORNIA. PRECIPITABLE WATER VALUES OF BETWEEN 1.00 AND 1.50 INCHES WILL BE ADVECTED INTO THE HIGHER ELEVATIONS OF THE CNTRL SIERRA BETWEEN 18Z WEDNESDAY AND 12Z THURSDAY. WITH THE WARM AIR OVER THE REGION SNOW LEVELS WILL BE RATHER HIGH AT AROUND 7000 FEET. SNOW LEVELS SHOULD STAY ABOVE 6500 FEET THROUGH 12Z THURSDAY. MOST OF THE PRECIPITATION LATE WEDNESDAY AND THURSDAY WILL BE RAIN WITH SNOW ABOVE 7000 FEET. O`HARA

Meanwhile, the forecast for 4.3 miles NW of Tahoe City, elevation 5281', says:

Wednesday: Mostly cloudy. Chance of snow. Snow accumulation 1 inch. Probability of measurable precipitation 50 percent. South wind 17 mph. High 47.

Wednesday Night: Mostly cloudy. Chance of snow. Snow accumulation 4 inches. Probability of measurable precipitation 50 percent. Low 32.

Thursday: Rain. Probability of measurable precipitation 60 percent. High 42.

So looking at this with admitted optimism, it looks like a high temp of 42-47 correlates to a snow level around 7000'.


Moving along to the next front....

.LONG TERM...THURSDAY THROUGH SUNDAY...
THE MODELS/ENSEMBLES CONTINUE TO SUPPORT A GULF OF ALASKA/EASTERN PACIFIC LOW PRESSURE SYSTEM THAT DIRECTS A MOIST SOUTHWEST FLOW OVER CA AND WESTERN NV THROUGH THE EXTENDED PERIOD. SUBTROPICAL MOISTURE IN THIS FLOW WILL PROVIDE SIGNIFICANT PRECIPITATION TOTALS AND HIGH SNOW LEVELS FOR THE SIERRA AND NORTHEAST CA. THE GFS IS SHOWING 6 INCHES OR MORE OF WATER EQUIVALENT ON THE WEST SLOPES OF THE SIERRA MAINLY NORTH OF MONO COUNTY...WITH POTENTIAL FOR 1 TO 2 INCHES IN FAR WESTERN NV. ADDITIONAL INFORMATION CAN BE FOUND IN THE HYDROLOGY SECTION BELOW. THE HIGH PRECIPITABLE WATER VALUES SLIDE SOUTH ON SUNDAY AS THE LOW WEAKENS AND MOVES INLAND. PRECIPITATION WILL DECREASE SIGNIFICANTLY DURING THIS TIME.

Note that NOAA is not yet predicting snow levels for the long term. They are, however, predicting temps: high of 42 on Friday, 46 on Saturday, 42 on Sunday.

So it's probably going to be touch and go at best. But if -- and it's a big if -- the snow levels stay around 7000, as the Wednesday forecast suggests, we might be getting the cement base we need to make it through the season.

Otherwise, it's time to start tuning up the bike, oiling up the mitt, and cursing Ullr.

[woodsskier]

Not to get too techie....looking at the information above.......highs between 42 and 46, I'd argue the snowline up another 500'.....7500, that's my call and I'm sticking to it....whcih isn't that bad, that means the snowline won't climb any higher than that over the whole storm.......

[El Chupacabra]

A series of storms that starts off wet & warm is ideal for the icy shit snowpack we have in Tahoe. Should bond better to the existing ice/rock/dirt, and allow for good accumulation.

Nonetheless, I'm going biking next weekend. Emigrant trail up by Truckee should be in good shape, no mosquitoes yet, right?

[freshies]

This could be like the New Years flood of '97.....if there was more snow to melt and runoff. This looks like it may wash away the lower elevation snow of all the resorts. Pray it comes in cold my brother!

not enough snow to cause run-off and ground so dry should absorb it all. plus, water equiv numbers roughly translate as follows: 1 " rain = 1' of snow...this basically says (we pray) the Sierra will get pounded above 7000 with wet snow this weekend. this will be our Dec sticky base we need

[onehotchili]

A series of storms that starts off wet & warm is ideal for the icy shit snowpack we have in Tahoe. Should bond better to the existing ice/rock/dirt, and allow for good accumulation.

yeah... last weekend i was at a 2 day seminar with some of Alpine Meadows top dog avy forecasters, and they said ideally it would be nice to get a smaller 1 foot wet storm, and a series of other smaller storms after that to add weight to the current snowpack and make sure some of the week layers down below will bond better.

this might not happen if we get a 3+ foot dump with this warm precip event later this week. they said that could be "bad" for the snowpack and controlling avalanches for the rest of the season... and were referring to the winter of '76-'77 (?) as being similiar to this year. that was before my time in the Sierra.

in any case, could definitely be interesting to see how things pan out later this week.

[skier666]

As the snow accumulates somewhere, I'm happy.

[Jim S]

1 " rain = 1' of snow...this basically says (we pray) the Sierra will get pounded above 7000 with wet snow this weekend.

I pray you are correct.

I'm off Friday-Sunday!! F-k yeah! PONTOON TIME!

[StormDay]

Meanwhile, the forecast for 4.3 miles NW of Tahoe City, elevation 5281', says:


Moving along to the next front....

Note that NOAA is not yet predicting snow levels for the long term. They are, however, predicting temps: high of 42 on Friday, 46 on Saturday, 42 on Sunday.

So it's probably going to be touch and go at best. But if -- and it's a big if -- the snow levels stay around 7000, as the Wednesday forecast suggests, we might be getting the cement base we need to make it through the season.

Otherwise, it's time to start tuning up the bike, oiling up the mitt, and cursing Ullr.

This is the pinpoint NWS I use for Alpine Meadows. It is for 7600'
http://www.wrh.noaa.gov/total_foreca...lon=-120.21625

It is pretty good on the snow totals and whether or not it is raining at the top of roundhouse.

Not to get too techie....looking at the information above.......highs between 42 and 46, I'd argue the snowline up another 500'.....7500, that's my call and I'm sticking to it....whcih isn't that bad, that means the snowline won't climb any higher than that over the whole storm.......

Unfortunately that forecast isn't so promising for Friday and Saturday during the day. Hopefully, the moisture will hit at night.

I'm seriously thinking about not driving the family up this weekend. Maybe solo for Sunday and try to talk Mrs Stormday into spending Prez day weekend skiing.

[mmcpheet]

water equiv numbers roughly translate as follows: 1 " rain = 1' of snow...this basically says (we pray) the Sierra will get pounded above 7000 with wet snow this weekend.

That SWE to depth conversion uses an 8.33 (repeating of course) % density for the calculation. Using a density more common to the Sierra for a warm storm somewhere in the 12-18% yields less than that for depth. But I like the optimism.

1" water content ÷ 12% density = 8.3" depth
1" ÷ 15% = 6.7"
1" ÷ 18% = 5.6"

[kidwoo]

That SWE to depth conversion uses an 8.33 (repeating of course) % density for the calculation. Using a density more common to the Sierra for a warm storm somewhere in the 12-18% yields less than that for depth. But I like the optimism.

1" water content ÷ 12% density = 8.3" depth
1" ÷ 15% = 6.7"
1" ÷ 18% = 5.6"

Silence!!!!!


1" = whoopdefreakin hoohah I'm goin skiing


You coming up this weekend?

[mmcpheet]

Only if we get 3% density.

6" ÷ 3% = 200"

[skimoore]

Only if we get 3% density.

6" ÷ 3% = 200"

Mmmmmm, that'd be nice....not snorkel deep, SCUBA deep.......

[mc_roon]

ill be up this weekend for the first time this season

[kidwoo]

Only if we get 3% density.

6" ÷ 3% = 200"

Yeah that would be a blast on all the refrozen glazed crap that's popped up.

[mmcpheet]

Yeah that would be a blast on all the refrozen glazed crap that's popped up.

I'll just be doing my normal 10° slopes anyhow. I was raging Snowkirk and Hot Wheels that last couple times I was up.