Daily Winter Weather Report
Date: Tuesday - 20 December 2011
|Station||Max Temp||Min Temp||Pres Temp||New Snow||Depth||Sky||Present Conditions|
|Grant Village||28||-4||-1||T||21||OC||Calm / Fog|
|West Entrance||35||5||14||0||13||-||Calm / Fog|
|Road Section||Status||Conditions||Public Access / Info|
|Gardiner to Mammoth||YR||Good||STA|
|Mammoth to Tower||YR||Good||STA|
|Tower to NE Entrance||YR||Good||STA|
|Beartooth Highway||CLOSED *||CLOSED *||CLOSED *|
|Canyon to Lake||CLOSED||CLOSED||CLOSED|
|Firehole Canyon Drive||CLOSED||CLOSED||CLOSED|
|Grant to South Entrance||Open||Rubber tracked oversnow concession vehicles|
|Junction to Chief Joseph Hwy||CLOSED *||CLOSED *||CLOSED *|
|Lake to East Entrance||CLOSED||CLOSED||CLOSED|
|Lake to West Thumb||CLOSED||CLOSED||CLOSED|
|Madison to Old Faithful||Open||Rubber tracked oversnow concession vehicles|
|Madison to West Yellowstone||Open||Rubber tracked oversnow concession vehicles|
|Mammoth to Norris||Open||Rubber tracked oversnow concession vehicles|
|Norris to Canyon||Open||Rubber tracked oversnow concession vehicles|
|Norris to Madison||Open||Rubber tracked oversnow concession vehicles|
|Old Faithful to Grant||Open||Rubber tracked oversnow concession vehicles|
|Tower to Canyon||CLOSED *||CLOSED *||CLOSED *|
YR=Year Round / NR=No Restrictions / STA=Snow Tires Advised / STR=Snow Tires Required
* NOTE: CLOSED FOR THE SEASON.
# Poor road conditions - bare spots and melting snow - Restricted to Snowcoaches Only.
The park service plowing schedule for roads for the spring season.
******** FOR CURRENT ROAD INFORMATION PLEASE CALL 307-344-2117 ********
East Entrance road is closed to wheeled vehicles.
Dangerous avalanche conditions may already exist in many back country areas, please call the Recorded Avalanche Advisory 406-587-6981 for the most current conditions.
Caution advised for snow falling off of building roofs. Park accordingly.
* * Be prepared for bitter cold (sub-zero) temperatures. See NWS Weather Forecast below for detailed information. * *
by the National Weather Service Riverton, WY
Today: Occasional flurries after 11:00 am. Patchy freezing fog before 11:00 am. Increasing clouds, with a high near 26°F. Wind chill values as low as -15°F.
Tonight: A 50 percent chance of snow. Mostly cloudy, with a low around 7°F. Wind chill values as low as -5°F. New snow accumulation of 1 to 3 inches possible.
Wednesday: Snow likely. Cloudy, with a high near 18°F and a low around -9°F. Night time Wind chill values as low as -25°F. Chance of precipitation is 70%. New daytime snow accumulation of 1 to 3 inches possible, with less than half an inch additional overnight.
Thursday: Occasional flurries before 11:00 am. Mostly sunny, with a high near 14°F and a low around -11°F.
Friday: Mostly sunny, windy, with a high near 17°F and a low around -3°F. Breezy, with a southwest wind 6 to 9 mph increasing to between 18 and 21 mph. Winds could gust as high as 31 mph.
Saturday: A 20 percent chance of snow showers. Partly sunny, with a high near 19°F and a low around 0°F.
|* * * Snow Depth Totals as reported at SNOTELs * * *|
|Station||Depth (inches)||Station||Depth (inches)|
|Black Bear||34||Parker Peak||32|
|Blackwater||36||Snake River Station||19|
|Evening Star||33||Sylvan Road||17|
|Fisher Creek||39||Thumb Divide||20|
|Grassy Lake||26||Two Ocean Plateau||41|
|Lewis Lake Divide||26||West Yellowstone||14|
|Madison Plateau||23||Whiskey Creek||19|
from the Gallatin National Forest Avalanche Center - December 20, 2011 - this report is by Doug Chabot. This advisory does not apply to operating ski areas.
Mountain temperatures are in the high teens Fahrenheit this morning with west to north winds at 15-30 mph and gusts hitting 40 mph. Today will start sunny, but clouds will increase later this afternoon as a cold front brings snowfall late tonight. Steady 20-40 mph winds will blow ahead of the front with nighttime temperatures dropping into the low teens Fahrenheit. By morning I'm expecting 3 to 4 inches of snow with storm totals of 6 to 8 inches by Wednesday night.
Snowpack and Avalanche Discussion:
The Bridger and Madison Ranges, the southern Gallatin Range and the Lionhead area near West Yellowstone:
With the exception of the northern Gallatin Range and mountains around Cooke City our mountain snowpack is weak, thin and not impressive. According to the NRCS we are at 65% of normal. That's giving winter a below average grade of "D" and Mother Nature doesn't grade on a curve. Weak snow is defined as unsupportable, unconsolidated, and faceted. Every time I step out of my skis or off my snowmobile I sink to the ground confirming its presence. This snowpack will have a difficult time supporting future snows.
My partner and I skied into Beehive Basin in the northern Madison Range on Sunday and found two feet (at most) of sugary, weak snow. In order to have an avalanche we need 4 things: a steep slope, a weak layer, a slab of snow sitting on that layer and a trigger. In Beehive, as in many parts of our advisory area, the missing ingredient is the slab. On slopes with deeper snowpacks this slab exists, which is why the ski patrols were able to release a few avalanches this past weekend with explosives.
For today, the avalanche danger is a function of depth. On slopes where the snowpack is greater than two feet deep, mainly on wind-loaded slopes, a slab exists and the Avalanche Danger is rated MODERATE. On slopes with less than two feet of snow the Avalanche Danger is rated LOW.
The northern Gallatin Range and mountains around Cooke City:
Mark and Eric spent the weekend digging snowpits around Cooke City. This trip was on the heels of Mark's tour up Flanders drainage in the northern Gallatin Range. Although miles apart, there were some similarities. Three or more feet of snow was measured in both areas, plus faceted, weaker snow was found near the ground. Stability tests indicated this layer is slowly strengthening and they concluded it would take a large storm to get it to avalanche; however, buried facets are never to be fully trusted. Occasionally the test columns propagated fractures. These results indicate variability within the snowpack as well as the possibility of triggering a slide. A natural avalanche outside Cooke City on Sunday is further evidence of this possibility.
For today the Avalanche Danger is rated MODERATE on all slopes steeper than 35 degrees. All other slopes have a LOW Avalanche Danger.
The next advisory tomorrow morning at 7:30 a.m. If you have any snowpack or avalanche observations, drop us a line at email@example.com or call us at: 406-587-6984.
PHOTOS, SNOWPITS, and VIDEOS
If you have any snowpack or avalanche observations, drop them a line at firstname.lastname@example.org or call: 406-587-6984.
For detailed Avalanche Terms utilized here, please see the Avalanche Glossary.
Information provided by Yellowstone National Park, National Weather Service and Gallatin National Forest Avalanche Center
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