Western Wyoming PM Forecast
Issued on Mon February 18, 2019 6:02 PM
SituationSkies were almost entirely clear at sunrise and although some clouds were present from mid-morning on, conditions were mostly sunny and beautiful. Summit winds were from the southeast with five to fifteen mile per hour averages. Temperatures remained cool with highs in the teens at all elevations.
The mostly clear day allowed for more avalanches to be noted that had occurred during the heaviest snowfall on February 14th to 16th. Some of these large avalanches involved early season layers. A snow profile from the crown at the Pyramid slide path has been posted that indicates failure on layers likely buried in January. Today at the Jackson Hole Mountain Resort avalanche mitigation performed on the North Ridge(a permanently closed area just to the north of the tram) produced very large avalanches. One slide, that was triggered by a large explosive, had depths of over twelve feet and likely ran on weak faceted snow from October. Another slide that was triggered by a typical sized air blast had a long propagation and depths of four to seven feet. This was the second time reduction efforts were performed in this terrain that is conducted in order to safely open the Tensleep Bowl area below. Snow surfaces include settled powder, near surface facets, and thin sun crusts. The snowpack continues to settle and slabs that lie throughout the backcountry are becoming less sensitive. They can still be triggered by the weight of a single person but the chance for natural activity has become unlikely and remote triggering has become less likely.
Forecast For Tuesday, February 19, 2019Light snow and flurries are possible overnight with partial clearing expected during the day on Tuesday. Temperatures are to remain on the cold side and will be slightly inverted with sub-zero temps expected at all elevations in the morning and highs in the low teens. Winds are to be light with five to ten mile per hour averages ranging from the west to the north.
The general avalanche hazard is expected to be Moderate in the Tetons. This reduction in the rating is only due to the fact that natural avalanches are not likely and slabs will be slightly less sensitive. Do not take this an indication that it is safe to go onto to steep terrain. Slabs that could be large in size could still be triggered by the weight of a single person. These slabs may be soft to hard and may break higher than they typically do on a slope. If caught in one of these events, the outcome may be fatal. The rating will remain Considerable at the Togwotee Pass and Southwest Trails areas where conditions remain in a more fragile state due to these areas having a weaker snowpack. This is especially true in the Togwotee Pass area where storms have consistently delivered less snow and cold temperatures have faceted the snowpack throughout the season.
Trend For Wednesday, February 20, 2019 AND Thursday, February 21, 2019Light snow is expected to develop Tuesday night and to continue into Thursday. Temperatures are to remain cold. The avalanche danger is not expected to change significantly during this time.
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