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Odds of Mid May Trip

Posted: Sun Apr 01, 2012 11:32 am
by oldranger
I am currently considering a mid May trip to S. Yosemite and have been doing a little research to determine the odds of a relatively snow free or better optimally snow covered so that travel is not too much hindered and mosquitos have not yet appeared.

Reviewing historical data (1963-last year) from Ostrander lake I have discovered that water content in snowpack has increased between April 1 and May 1 approximately 30% of the time. Two years had 0 snow on May 1. I am waiting to see what actual water content is now through the field survey. The sensor indicates almost 17 inches and about 4 ft. of depth. If relatively warm spring continues there is a good chance that Mid may will be relatively snow free on s. slopes to well above 9,000 feet. The first few days of my trip will meet that criteria but then I will be heading to n. slopes and a higher probability of walking on snow. About 8 days into the trip I will be topping out at about 9800 ft.

Even though it is early in the season water should not be terribly high but has anyone ever done Gravelly Ford early?

Of course another alternative is to head into s. Kings Canyon or do High Sierra trail as far as I can comfortably but HST doesn't offer any special fishing opportunities and I am planning a trip later in the season to Ranger Lakes. But I have not visited s. yosemite and that is my first choice.

Mike

Re: Odds of Mid May Trip

Posted: Sun Apr 01, 2012 2:14 pm
by Mike M.
Mike, I think mid-May might be pushing it. Despite the low snow year, you can expect to see lots of snow on the ground above 6500 feet (my best guess) in mid May. Streams will be raging.

As a point of reference, I did an early season (late May) hike into Rae Lakes in 1977, a very low snowfall year. We did a counterclockwise loop from Cedar Grove, and dayhiked into the Sixty Lakes Basin and went up to Baxter Lakes as well. We encountered patches of snow at about the 10,000 ft level; Glen Pass was covered in snow. The lakes in Rae Lakes Basin were still iced over. There were patches of snow on the ground at Rae Lakes, with significant snowfields present on the slopes. Getting around was easy. I'd do it again in a flash. But plan on lots of snow and difficult stream crossings where there are no bridges.

As you know, the further north you go, the more snow you get. I'm guessing in 1977, conditions in southern Yosemite at 6500 ft were similar to 10,000 ft in King's Canyon National Park. If your route involves forested travel above 6500 ft, get ready for lots of uncomfortable travel (hip plunges and the like) on snow.

Mike

Re: Odds of Mid May Trip

Posted: Sun Apr 01, 2012 8:20 pm
by oldranger
Mike,

I think you are a tad bit optimistic about snow conditions. Taking the Chiquito Cr. Snow survey records (6800 ft) there were 13 May 1sts (since 1963)with no snow cover at all (several others with no recordings). Several others had less than 5" of water. May 1 of 77 was a 0 year so your extrapolation from SEKI doesn't fit (think about it. You are talking about around an 11° temperature difference figuring in both latitude and elevation difference). Also in only 3 year during that time period did the water content of the snowpack increase between April 1 and May 1. Several year during that time period the snow pack lost from 19 to 21 inches of water. That being said there is a huge difference between 6800 ft and 8,200 feet to 9800 feet that I plan to travel. Luckily I can make a go/no go decision right up to the day I start. If the remote survey at Ostrander zero's out anytime before May 15th I will go for it.

Mike

Re: Odds of Mid May Trip

Posted: Sun Apr 01, 2012 9:59 pm
by tim
I'd agree with Oldranger and note that the Tahoe basin where we are this week (albeit East side of the crest) has fairly sparse coverage already on most south facing slopes below 7000ft.

Re: Odds of Mid May Trip

Posted: Mon Apr 02, 2012 9:47 am
by Mike M.
Mike, I could very well be wrong. But mid-May is awfully early in any year.

Where exactly are you planning to go?

I say go for it even if you expect to encounter a lot of snow. Just go prepared -- eyes wide open. Then post a report so we can vicariously enjoy your experience.

Mike

Re: Odds of Mid May Trip

Posted: Mon Apr 02, 2012 10:38 am
by Wandering Daisy
Snow surveys are designed to give a large picture of stored water in the Sierra. They are NOT designed for determining snow melt at all locations. There are vast differences depending on slope orientation, location north-to-south, or east-to-west, and altitude. The bigger problem than snow on the ground is water in the creeks, especially in Yosemite. Peak runoff, although a short time period, makes LOTS of creeks difficult if not unsafe to cross. Peak runoff depends on the rate of melting. If we get lots of late snow and then suddenly hot May, creeks could be very high. Patches of snow on north slopes and above 10,000 feet are common in May. A mid-May trip is certainly do-able, but will not likely be totally snow free. I would just be sure that if you have to cross a major stream, do it where there is a bridge. Look at the size of the watershed above the crossing. If small, probably no big deal. If large, it may be a problem.

I recall that one factor is the Beasears Road if you want to access from a trailhead up near Granite Creek. Probably good to call Forest Service on this before you go.

Re: Odds of Mid May Trip

Posted: Mon Apr 02, 2012 11:36 am
by TehipiteTom
Mike,

This thread is really confusing. One of you guys needs to be named something other than Mike.

Mike

Re: Odds of Mid May Trip

Posted: Mon Apr 02, 2012 5:45 pm
by oldranger
Daisy

Not unfamiliar with all of your points. I pay particular attention to the slope aspect of the sites when extrapolating to the area as a whole. Using the right site has given me pretty accurate estimates of the conditions I have faced in the past. May at these elevations this year can't be any worse snowwise than my mid july trip last year to Tunemah! As you suggested my prime concern is Gravelly Ford. Given the relativly low elevation there is likely to be a tree or log jam not too far from the crossing. No bridges in the area though. Unless April has a lot of snow I think that the Beasore Road is not likely to be a problem. If it is then clearly the trip would be almost entirely snow covered because the road is substantially lower than most of the trip.

Mike

Re: Odds of Mid May Trip

Posted: Mon Apr 02, 2012 10:50 pm
by paul
Oldranger -
I have been studying the sensors (as usual) in looking forward to my spring backcountry ski trip. So far this year is looking a lot like 2007. My particular focus has been the Emigrant Wildernss since that's my prime target this year. The sensors there are very close to the 2007 numbers. I just checked the Ostrander sensor and it is slightly ahead of the 2007 numbers for today - 16.84 today, 14.02 on 4/2/2007. For comparison, I went to the Emigrant that year in late April/early May, and was skiing above 8500 feet. Ostrander and that area typically gets less snow than the Emigrant does. in 2007 on may 1st there was 3.58" of water at the Ostrander sensor, which would translate to about 7-8" of snow given the typical late spring density. If the exposure is what it seems to be from the description and from Google Earth, then it ought to be pretty indicative of the area. I think your analysis is fair, assuming April is not a wet one. Of course, I'm hoping for all the snow we can get in April for my skiing conditions. But as long as there hasn't been much new snow in the 2 weeks prior to your trip, you ought to be able to do it even if there is still a fair amount of snow (assuming you can get to the trailhead). Just plan for early morning starts, and you'll be cruising along on the top of a nice crust as easy as walking a trail until around 10:00 - or maybe noon in the shade.

Re: Odds of Mid May Trip

Posted: Tue Apr 03, 2012 8:20 am
by oldranger
Paul,

You are right about early am starts. In 1983 I broke a ski as I was skiing out during an early June trip. I actually changed course to maximize my downhill. Early am was easy but postholing in the PM sucked then the last downhill I did on one ski with traverses and kick turns until I got to dirt. It was a great adventure though.

Mike