Avalanche Forecast
Dec 25th, 2018–Dec 27th, 2018
Alpine
Below Threshold
The avalanche danger rating in the alpine will be below threshold
Treeline
Below Threshold
The avalanche danger rating at treeline will be below threshold
Below Treeline
Below Threshold
The avalanche danger rating below treeline will be below threshold
Alpine
Below Threshold
The avalanche danger rating in the alpine will be below threshold
Treeline
Below Threshold
The avalanche danger rating at treeline will be below threshold
Below Treeline
Below Threshold
The avalanche danger rating below treeline will be below threshold
Regions: Olympics.
The bottom line: Fresh and shallow wind slabs will likely develop on steep lee slopes near and above treeline Wednesday. However, we have no direct snowpack or avalanche observations from this area. Take the time to evaluate conditions for yourself before entering avalanche terrain.
Snow and Avalanche Discussion
Snow depths vary widely depending on aspect and elevation in the Hurricane Ridge area due to stormy conditions over much of the last two weeks. The Hurricane Ridge area received a healthy dose of snow from Sunday's storm; we estimate up to 12" of snow fell in non-wind affected areas. Areas below treeline are beginning to fill in for the first time this winter.
We have not had any direct snowpack observations from the Hurricane Ridge area in nearly 2 weeks. Keep this in mind and buffer in the extra uncertainty while making terrain selections.
We have not had any direct snowpack observations from the Hurricane Ridge area in nearly 2 weeks. Keep this in mind and buffer in the extra uncertainty while making terrain selections.
Forecast schedule
For the 2018-19 winter season, avalanche hazard ratings will be issued for the Olympics Friday through Sunday and during holidays.
On days that the Hurricane Ridge road is closed, No Rating will be applied. We will continue to provide general snowpack and weather summaries for the Hurricane Ridge area even when No Rating is issued.
On days that the Hurricane Ridge road is closed, No Rating will be applied. We will continue to provide general snowpack and weather summaries for the Hurricane Ridge area even when No Rating is issued.
Regional Synopsis
In most parts of the state, a stout melt freeze crust was formed when it rained to high elevations around Thanksgiving. The one exception to this event was in the East North Zone, where the precipitation from the Thanksgiving storm was all snow. A quick storm at the end of November put a small amount of snow above the melt-freeze crust, and preserved the older basal facets in the northeastern areas.
Cold and clear weather dominated the first week in December, with valley fog and very cold temperatures east of the crest. The surface snow sat around and decomposed. Surface hoar grew large on top of this.
The jet stream took aim at the Pacific Northwest in the 2nd week of December. Most notably, light storms buried and preserved a widespread layer of surface hoar and/or near surface facets on December 9th. From December 9th to December 23rd, storms kept coming. Freezing levels fluctuated, but never moved much above 5000ft throughout the Cascades (although the southernmost volcanoes and Mt. Hood saw rain well above 6000).
Initially, the storm track favored the northern zones. The accompanying avalanche cycle began on December 11th. Most of these slides were soft slabs, but some propagated widely on the December 9th layer. Higher snowfall totals in the West North resulted in very large (D3+) avalanches in the mountains along Hwy 542.
A second, and larger avalanche cycle occurred during heavy snowfall and strong wind events between December 18th and 20th. Although these cycles were once again most prevalent in the northern and eastern zones, big storm totals around Mt. Rainier tipped the balance down south as well. This 2nd cycle was impressive, with very large and destructive avalanches (some D4) reported. The culprit was once again the December 9th surface hoar/facets (and/or the basal facets in the northern and eastern zones).
Today we have a large difference in snowpack depths between the Pacific Crest and the Eastern Slope. This is nothing unusual, as more often than not the west side of the Cascades and the passes get more snow than areas further east. Moving forward, places with a deep snowpack (say greater than 5ft) and warmer temperatures may continue to gain strength. Areas with a shallow snowpack (say less than 3.5ft) may take much longer. In a general and applied sense, this means the avalanche danger/conditions may begin to diverge between the western and eastern zones.
As the skies clear and we move into high pressure, take note as to which avalanche paths have run large on deep, weak layers, and those which haven’t. Be sure to track surface conditions, as this next period of cold, clear weather may create the next weak layer when the storm track does turn back toward us. As always, please share your photos and experiences with us!
Happy Holidays.
Cold and clear weather dominated the first week in December, with valley fog and very cold temperatures east of the crest. The surface snow sat around and decomposed. Surface hoar grew large on top of this.
The jet stream took aim at the Pacific Northwest in the 2nd week of December. Most notably, light storms buried and preserved a widespread layer of surface hoar and/or near surface facets on December 9th. From December 9th to December 23rd, storms kept coming. Freezing levels fluctuated, but never moved much above 5000ft throughout the Cascades (although the southernmost volcanoes and Mt. Hood saw rain well above 6000).
Initially, the storm track favored the northern zones. The accompanying avalanche cycle began on December 11th. Most of these slides were soft slabs, but some propagated widely on the December 9th layer. Higher snowfall totals in the West North resulted in very large (D3+) avalanches in the mountains along Hwy 542.
A second, and larger avalanche cycle occurred during heavy snowfall and strong wind events between December 18th and 20th. Although these cycles were once again most prevalent in the northern and eastern zones, big storm totals around Mt. Rainier tipped the balance down south as well. This 2nd cycle was impressive, with very large and destructive avalanches (some D4) reported. The culprit was once again the December 9th surface hoar/facets (and/or the basal facets in the northern and eastern zones).
Today we have a large difference in snowpack depths between the Pacific Crest and the Eastern Slope. This is nothing unusual, as more often than not the west side of the Cascades and the passes get more snow than areas further east. Moving forward, places with a deep snowpack (say greater than 5ft) and warmer temperatures may continue to gain strength. Areas with a shallow snowpack (say less than 3.5ft) may take much longer. In a general and applied sense, this means the avalanche danger/conditions may begin to diverge between the western and eastern zones.
As the skies clear and we move into high pressure, take note as to which avalanche paths have run large on deep, weak layers, and those which haven’t. Be sure to track surface conditions, as this next period of cold, clear weather may create the next weak layer when the storm track does turn back toward us. As always, please share your photos and experiences with us!
Happy Holidays.
Weather Synopsis for Wednesday & Thursday
A shortwave trough plunges southeast into the region behind a cold-front passing the mountains around noon on Wednesday. With seasonably cold temperatures in place, the mountains will see increasing snow in the morning and snow shower activity in the afternoon. During the day on Wednesday expect 2-6" in the passes, around 6" for Mt. Baker, and 6-8" for Paradise and Mt. Hood areas, while the Cascades east slopes pick up 1-3". Generally light snow shower activity will continue Wednesday night adding 1-4" in many locations along the Cascades west slopes and appoximately 6" at Mt. Hood, with 0-2" on the Cascades east slopes. Periods of somewhat heavier snow possible in convergence bands over the central Washington Cascades.
Snow showers decrease and generally end on Thursday as flow turns N-NWerly. High clouds should continue to spill over a "dirty ridge" building offshore.
The pattern continues Thursday night as the ridge edges slightly closer.
On Friday, a warm front arrives over the top of the ridge from the west, bringing moderate rain or snow and rising snow levels along with increasing SW winds.
Snow showers decrease and generally end on Thursday as flow turns N-NWerly. High clouds should continue to spill over a "dirty ridge" building offshore.
The pattern continues Thursday night as the ridge edges slightly closer.
On Friday, a warm front arrives over the top of the ridge from the west, bringing moderate rain or snow and rising snow levels along with increasing SW winds.