Avalanche Forecast
Jan 8th, 2019–Jan 9th, 2019
Alpine
3:
Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
2:
Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
2:
Moderate
The avalanche danger rating below treeline will be moderate
Alpine
3:
Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
2:
Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
2:
Moderate
The avalanche danger rating below treeline will be moderate
Regions: Mt Hood.
The bottom line: New snow totals and wind directions have been more variable than usual, so take the time to evaluate local loading patterns in your area before stepping into steep wind-affected terrain. Rising snow levels and rain should cause wet snow hazards to increase rapidly below treeline later in the day.
Regional Synopsis
January 7, 2019
This latest round of storms in early January continues to highlight some of this season’s region-wide themes in our snowpack. I’d describe them as Bottom to Top, North to South, and East to West. Let’s take a look at each of these.
Bottom to Top:
In general, this winter has been on the warm side in the Cascades. Nowhere is that more evident than in the lack of low elevation snow. Heavy rain events continue to wash-away and thoroughly wet the lower elevation snowpack. In most regions, you will see a substantial increase in the height of snow from low elevations (3000 ft), to mid elevations (4500 ft), and again at upper elevations (5500/6000 ft). Above the typical rain lines (5000-6000 ft) a deep and cold mid-winter snowpack exists.
North to South:
With few exceptions, this season’s storm tracks have favored the North Cascades. Sunday, Mt Baker’s Heather Meadows weather station passed 100 inches of snow on the ground. A quick look around the state’s weather stations demonstrates just how deep this snowpack is. Most other locations are reporting between 50 and 75 inches. The massive amounts of snow for the northern forecast zones are reflected in several impressive avalanche cycles spread out over the last month.
East to West:
Several stacked persistent weak layers have been buried in the eastern forecast zones. This isn’t unusual, but it is noteworthy. The thickness of the slabs over these weak layers can vary greatly. Closer to the Cascade Crest, the deep snowpack may more closely resemble Stevens or Snoqualmie Passes. Further east, shallower snowpacks and significant variability are keeping snowpack assessment tricky.
So what now? Well, on January 3 and 4 a high elevation rain event impacted areas from Mt Baker to Mt Hood. In many locations, this has created a firm and thickening crust. In these locations, this new crust is limiting the impacts of any deeper weak layers. In locations that didn’t receive as much rain like WA Pass, Mission Ridge, Crystal Mt, and White Pass, how the small amount of rain impacted the mid and lower snowpacks remain to be seen.
One thing is for sure, we’re not even a month into the winter season, there’s a lot more winter to come.
This latest round of storms in early January continues to highlight some of this season’s region-wide themes in our snowpack. I’d describe them as Bottom to Top, North to South, and East to West. Let’s take a look at each of these.
Bottom to Top:
In general, this winter has been on the warm side in the Cascades. Nowhere is that more evident than in the lack of low elevation snow. Heavy rain events continue to wash-away and thoroughly wet the lower elevation snowpack. In most regions, you will see a substantial increase in the height of snow from low elevations (3000 ft), to mid elevations (4500 ft), and again at upper elevations (5500/6000 ft). Above the typical rain lines (5000-6000 ft) a deep and cold mid-winter snowpack exists.
North to South:
With few exceptions, this season’s storm tracks have favored the North Cascades. Sunday, Mt Baker’s Heather Meadows weather station passed 100 inches of snow on the ground. A quick look around the state’s weather stations demonstrates just how deep this snowpack is. Most other locations are reporting between 50 and 75 inches. The massive amounts of snow for the northern forecast zones are reflected in several impressive avalanche cycles spread out over the last month.
East to West:
Several stacked persistent weak layers have been buried in the eastern forecast zones. This isn’t unusual, but it is noteworthy. The thickness of the slabs over these weak layers can vary greatly. Closer to the Cascade Crest, the deep snowpack may more closely resemble Stevens or Snoqualmie Passes. Further east, shallower snowpacks and significant variability are keeping snowpack assessment tricky.
So what now? Well, on January 3 and 4 a high elevation rain event impacted areas from Mt Baker to Mt Hood. In many locations, this has created a firm and thickening crust. In these locations, this new crust is limiting the impacts of any deeper weak layers. In locations that didn’t receive as much rain like WA Pass, Mission Ridge, Crystal Mt, and White Pass, how the small amount of rain impacted the mid and lower snowpacks remain to be seen.
One thing is for sure, we’re not even a month into the winter season, there’s a lot more winter to come.
Weather Forecast
Weather Synopsis for Wednesday night through Friday
A rainband associated with a low tracking northward offshore will bring rain at generally elevated snow levels west of the Cascade Crest. Cold air east of the Cascade Crest will gradually erode from south to north, but may still provide a messy mix of rain, sleet and snow east from the lower Cascade passes eastward in the evening and overnight hours. Mt. Baker continues to be favored by the southerly flow pattern (2" of water overnight), but other areas will start receiving moderate precipitation overnight.
The passage of the rainband is likely to decrease easterly flow enough to change both Stevens and Snoqualmie Passes to rain by Thursday early morning and scour out the and scour out the cold air pool east of the Cascade Crest as the rainband doesn't provide much cooling aloft. Precipitation type has been very difficult to forecast during this event.
A weak warm front will brush the region on Thursday, bringing generally light rain and snow on a southerly flow.
Thursday night and Friday should see some clearing as most of the weather action stays just offshore to our west with a ridge building over eastern Washington, keeping us dry.
Avalanche Problems
Wind Slabs
The distribution and size of newly formed wind slabs likely vary more than usual in the Mt. Hood area. The Mt. Hood Meadows area saw light winds and only a few inches of snow, while Timberline and Skibowl received a bit more snowfall and stronger east winds Tuesday. Winds are forecast to increase for all locations Wednesday, so look for new and recent snow to form fresh wind slabs once again.
Look for uneven snow surfaces, snow drifts, and fresh cornices to identify where fresh wind slabs may have formed. Feeling for firm or hollow sounding snow provides clues that you may trigger a wind slab avalanche on nearby steep slopes.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Likely
Expected Size: 2 - 2
Loose Wet
The weather forecast is tricky for Wednesday but if rising snow levels and rain occurs during the afternoon, loose wet avalanches will become likely below treeline. Watch for rapid changes in the surface snow; natural rollerball or pinwheels are a sign of the increasing loose wet hazard. Avoid very steep slopes where even a small avalanche could cause injury.
Aspects: All aspects.
Elevations: Below Treeline.
Likelihood: Likely
Expected Size: 1 - 1