JACKSON, Wyo. – So far, February has been cold with infrequent and inconsistent snowfall. However, a major pattern change is set to take hold around President’s Day with frequent storms likely through the end of February along with the potential for significant snowfall.
JHMR impacted by highly localized storm on Valentine’s Day
Most of the past week has been quiet across Teton County, and for most areas this remained true on Tuesday, February 14 as a seemingly weak storm moved through. The storm came in with predominately northeast winds, which is not a favorable wind direction for snow in the Tetons. And most areas did receive only light snowfall.
However, a localized band of heavy snow set up over Jackson Hole Mountain Resort, producing 14 inches on the upper mountain above 9,000 feet and 8 inches at mid-mountain.
Snowfall amounts were much lighter elsewhere, including 3 inches near Surprise Lake in Grand Teton National Park, 6 inches at Grand Targhee and 1 inch at Snow King. The Town of Jackson only received 0.4 inches.
So what happened? While northeast winds are not typically favorable, a cold front moving from north to south across Teton County stalled across the area for an extended period of time during the day on Tuesday, which likely acted as a focal point for snow due to converging winds along the frontal boundary.
Although it’s tough to prove this on such a microscale level, it’s possible the front banked up against the east side of the southern end of the Teton Range, forcing the moist airmass to rise and lead to locally heavy snowfall rates.
The atmosphere was also unstable on Tuesday, which could have contributed to highly localized bands of heavy snow developing (similar to the way pop-up showers/thunderstorms behave in the warmer months).
Another interesting aspect of this storm was the dry and powdery nature of the snow. We are used to receiving low-density powder snow in the Tetons, but this snowfall was exceptionally dry even by our standards.
A “typical” low-density powder event in the Tetons will have a snow-liquid ratio of 15 to 1 (1″ of liquid converts to 15″ of snow) or 6.7% density. However, this storm featured a snow-liquid ratio of 25 to 1 or 4% density. That’s about as “blower” as it gets!
This was a unique event and one that resulted in a localized area – the upper portion of Jackson Hole Mountain Resort – being very lucky compared to its neighbors.
Jackson Hole’s Rendezvous Bowl Plot averages 73 inches of snow in the month of February, and a little more than halfway through the month, this location has received 35 inches this February. Snowfall numbers are much lower than average for the first half of the month elsewhere, including the Town of Jackson who has only received one inch of snow total so far this month.
Snowpack Update
Tuesday’s highly localized snow event did not do much for our snowpack on a larger scale. In fact, snowpack in the Upper Snake River Basin has dipped below average for the first time since the beginning of the season, currently sitting at 98% of average.
For the state of Wyoming as a whole, snowpack is generally near to above average in most areas.
Across the Western U.S., snowpack is above average across the Sierra Nevada Range, Wasatch Range, Western/Central Colorado Rockies and much of the Southwest U.S. Snowpack is generally near average across the Pacific Northwest and Northern Rockies and below average in British Columbia and Alberta.
A cold February for the Jackson Hole Valley
Cold air has settled into Teton County at the onset of each dry spell, and inversions have kept the cold air locked into the valley for extended periods of time.
So far this month, temperatures are running 9.5ºF below average in the Town of Jackson and 6ºF below average at the Jackson Lake weather station near Moran. The Town of Jackson has recorded low temperatures below zero on 11 out of 15 days so far this month. Brrr!
For perspective, the long-term average high in Jackson in February is 34ºF and the average low is 8.5ºF.
Inversions mix out more easily on Teton Valley side during the afternoons compared to the Jackson side. As a result, Teton Valley has experienced more seasonal temperatures so far this month during what has otherwise been a dry month. Temperatures at the Alta weather station have been right around average so far this February.
Snowfall potential increases substantially next week
Cold and dry conditions will prevail on Thursday and Friday with sunny skies and highs in the teens at all elevations. On Saturday, temperatures will start to warm up a bit as milder air and gusty winds develop ahead of an approaching weather pattern change.
A trough of low pressure is expected to become the dominant pattern across the Western U.S. during late February and a strong jet stream is expected to set up in a favorable position to direct frequent storms toward the Tetons.
A weak storm will bring a round of light snow on Saturday night and Sunday morning. Then, a stronger storm is expected to impact our area from Sunday night through Monday night with heavy snow possible along with gusty winds. Another storm is possible shortly thereafter next Tuesday-Wednesday (February 21-22).
The first half of next week could feature high-impact travel conditions at all elevations, while skiers and riders will certainly enjoy the new snow.
Extended Outlook
An active pattern is likely to continue through the end of February and into the beginning of March with more frequent shots of snow compared to recent weeks. Temperatures are also expected to stay consistently below average.
Alan Smith, Meteorologist
