WEATHER ALERT 8/30

Questions and reports related to Sierra Nevada current and forecast conditions, as well as general precautions and safety information. Trail conditions, fire/smoke reports, mosquito reports, weather and snow conditions, stream crossing information, and more.
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SSSdave
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Re: WEATHER ALERT 8/30

Post by SSSdave » Thu Sep 14, 2017 10:34 pm

c0ryh wrote:... Do you guys think this is enough?...


If a howling snow storm is occurring with below freezing temperatures, don't go any further than the lakes east of the pass. From there a person can easily escape just dropping down the trail. Humphreys Basin is one of the worst places to be in strong below freezing winds because there is little to slow winds down. That is why that are is so...desolate. Go here:

https://www.windy.com/?700h,38.083,-120.542,5

On the right side of the page control bar with Wind selected change from Surface to 3000 meters.
On the page bottom time line, move the date to Tuesday mid day.

That huge powerful trough is what is coming. It is more like storm weather one sometimes sees in early October but then this year and this summer has not be normal. Of note the forecasts state there is not supposed to be much moisture with its passage for whatever that is worth. For what that forecast is worth weather will be bad until Friday.

Change the control from Wind to Temperature. Toggle click the temperature bar at bottom to Farenheit.
Use the zoom controls to zoom into the Bishop region until you can identify large Desolation Lake to the west. Then select that spot with a mouse click that will provide information for that location as you move the date bar. Note how on Wednesday forecast temps drop to 24F and stays below freezing a long time.

All those forecasts are mere possibilities and it is far enough days out that things might change as your trip approaches. It could be less severe or it could be worse.

David








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rightstar76
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Re: WEATHER ALERT 8/30

Post by rightstar76 » Fri Sep 15, 2017 2:44 am

Thanks for sharing that web site Dave. I never knew about it until now. I tested it out and it's a nice addition to NWS. Speaking of which, their forecast discussions are pointing toward snow next week Wed through Fri at 7000 feet. Yikes. What a way to end summer.

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webdweeb
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Re: WEATHER ALERT 8/30

Post by webdweeb » Fri Sep 15, 2017 8:08 am

Regarding the front and its remnants: we had two "exciting" nights on the Rae Lakes Loop; September 9th at Middle Rae Lake, which featured very high winds from the south and buffeted our tents all night long (all managed to survive the evening), and September 11th at Charlotte Lake, which featured an epic thunderstorm that parked over the lake for most of the night. Our tents (BA Flycreek UL2 HV) definitely got a thorough testing on those nights.

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Paloma
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Re: WEATHER ALERT 8/30

Post by Paloma » Mon Sep 18, 2017 2:38 pm

We were camped at about 11K when that late August storm rolled in overnight. It was pretty terrifying as we squatted on our foam pads and the lightening lit up the night sky. We met lots of other terrified campers the next morning that thought they might not make it through the night. The next morning it looked like things were improving and we had just reached Muir Pass and the whole things started again. And again at Thousand Island Lakes. Now it looks like lightening has been replaced with cold and wind this week. Don't know which is worse? :-)

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Re: WEATHER ALERT 8/30

Post by rlown » Mon Sep 18, 2017 10:03 pm

lightning is worse. snow is snow, and cold is expected this time of year.

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Re: WEATHER ALERT 8/30

Post by SSSdave » Wed Sep 20, 2017 6:14 pm

Well this Wednesday afternoon Reno NWS forecast discussion is playing out like had been advertized as possible a week ago in the long range forecast. This afternoon they cranked up the snow amounts for the Sierra though it is not a strong storm per what is possible mid October just strong for the third week of September. One look at the below vapor satellite loop ought be enough to sober any doubters up. Will expect there will be a modest number of groups chased out of the high country surprised by this weather.

http://www.ssd.noaa.gov/goes/west/weus/h5-loop-wv.html

http://www.wrh.noaa.gov/total_forecast/ ... &version=0


Expect RAPIDLY CHANGING WINTER CONDITIONS at higher elevations
in the Sierra tonight and at higher passes in NE California,
the Tahoe Basin, and eastern Sierra, including Donner Pass on
I-80 and on the Mount Rose highway above 8,000 feet. This is not a
big snow storm by any means (a few inches above 8,000 feet) but
anyone traveling over mountain passes or hiking in the higher
elevations will need to be prepared.

A cold front moving south across northern CA this afternoon will
sweep across the Tahoe Basin this evening and across Mono/Mineral
counties after midnight. Prefrontal wind gusts 30-40 mph (higher
in wind prone locations) and ridge gusts 70-90 mph are occurring
this afternoon and will continue through the evening, and then
shift to the west/northwest and slowly decrease overnight post
frontal. Lake winds will continue to increase this
afternoon/evening with very choppy conditions on area lakes. Small
boats, kayaks and paddle boards on Lake Tahoe or Pyramid lake
will be prone to capsizing through this evening.

New computer simulations show an unstable, saturated layer below
700 mb with the frontal passage. This increases the potential for
several hours of moderate precipitation in the Sierra with the
frontal passage. Snow levels may fall to around 7,500 feet in the
Tahoe Basin/Alpine County by Thursday morning and to around 8,500
feet in Mono County. This will be the first snow event of the
season with a few inches of accumulation possible above 8,000 feet
along with very strong winds. These will be DANGEROUS CONDITIONS
for hikers, campers or anyone exposed to the weather at those
higher elevations.


Silver lining through all this is by Monday the Sierra will be into warmer fair weather as all the above pushes east. Already set up a 3-day car camping fishing trip for 3 of us in the Bishop Creek areas over the following weekend when we'll also get to see some of the early fall aspen leaf color.

David

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rlown
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Re: WEATHER ALERT 8/30

Post by rlown » Wed Sep 20, 2017 6:28 pm

Hmm. My group hikes in out of Tuolumne on the 25th.. I'm completely content. The right clothing and good tents so I don't see a problem. We generally fish after the rod guides freeze anyway.

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Re: WEATHER ALERT 8/30

Post by Hobbes » Thu Sep 21, 2017 8:06 am

I think the weather service might have underestimated the storm. In fact, perhaps everyone is surprised by the impact. Not a 'true' winter storm, right ...

Image

Image

PS McCoy is at 9,600', while the summit is 11k.

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Re: WEATHER ALERT 8/30

Post by SSSdave » Thu Sep 21, 2017 10:14 am

This morning at Kirkwood. Just took care of my skiing season pass this morning. Have the Epic Tahoe Value Pass - Senior so will be skiing Heavenly, Kirkwood, and Northstar this winter. Excites me seeing this early snow on the last day of summer before the fall aspen leaf season has barely started. Most of the above is certain to melt quickly due to radiation heating from the still warm ground however snow like this will more rapidly chill that ground for subsequent storms. Saw a picture this morning of Mt Bachelor in Bend where they got more than a foot. The Southern Sierra did receive more than was expected from the long range and given how much that Mammoth image shows, imagine there are a few people out in the High Sierra this morning regretting where they are.

Image
Last edited by SSSdave on Thu Sep 21, 2017 10:17 am, edited 1 time in total.

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maverick
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Re: WEATHER ALERT 8/30

Post by maverick » Thu Sep 21, 2017 10:15 am

Tuolumne Meadows
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Professional Sierra Landscape Photographer

I don't give out specific route information, my belief is that it takes away from the whole adventure spirit of a trip, if you need every inch planned out, you'll have to get that from someone else.

Have a safer backcountry experience by using the HST ReConn Form 2.0, named after Larry Conn, an HST member: http://reconn.org

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