JACKSON, Wyo. – Above-average warmth has returned to Jackson Hole, and a storm loaded with subtropical moisture produced 1-2 feet of heavy, wet snow in the Tetons on Tuesday-Wednesday, while rain has been falling in the valley. Lightning strikes also occurred in the Tetons on Wednesday morning.
Recent Weather Pattern
Last week, for one of the rare times this season, it actually felt like a typical winter weather pattern in the Tetons with cold temperatures, abundant snowfall, and powder snow quality.
A storm cycle during the middle of last week produced 1-2 feet of snow in the Tetons, and most importantly, cold temperatures, which resulted in excellent snow quality. Skiing conditions were better last week than they have been all season as a result.
The valley also saw impressive snowfall last week, with 8.3 inches of snow recorded in the town of Jackson from February 17-19.
As the storm cycle came to a close, the town of Jackson saw its coldest temperature of the season with a low of -11ºF on February 20. Amazingly, this is the only time this season the temperature has dipped to -10ºF or lower at the JKNW4 weather station in Jackson.
The cold snap proved to be short-lived as temperatures warmed up significantly last weekend, reaching a high of 43ºF in town on Sunday. By Monday, spring-like warmth had fully taken hold with a high of 49ºF.
A strong storm involving a plume of subtropical moisture impacted the area on Tuesday and Wednesday, and this was similar to many of the warm, wet, and windy storms we saw back in December.
Snowfall from early Tuesday morning through early Wednesday morning ranged from 1 to 2 feet in the Tetons above 8,000 feet, including 23 inches at Grand Targhee and 13-15 inches at Jackson Hole Mountain Resort.
Snow-liquid ratios with this storm were around 8 to 1 in most areas (1″ of liquid = 8″ of snow), and snow density was around 12-13%, indicative of a very wet, dense snow event. Snow water equivalent ranged from 1.3 to 2.5 inches across most of the Teton Range.
The Jackson Hole Valley received snow initially on Tuesday morning, but then snow changed to rain on Tuesday afternoon. The town of Jackson picked up 0.45 inches of precipitation on Tuesday and Tuesday night, but only 2 inches of snow, as much of what fell was in the form of rain.
On Wednesday, more intermittent mountain snow showers and valley rain showers have continued, and there has been a convective element to these showers due to an unstable atmosphere. Since first thing on Wednesday morning, Jackson has picked up an additional 0.12 inches of rain.
In fact, lightning strikes occurred over the Tetons around mid-morning on Wednesday, forcing temporary lift closures at both Grand Targhee and Jackson Hole Mountain Resort. The strikes were closer to Targhee than JHMR, and if you happened to be skiing at Targhee, you may have experienced a rare “thundersnow” event.
Below is a 7-day weather summary for the town of Jackson. Note that the log for February 25 (today) was for the period ending at 7 a.m.
For perspective, the average high and low in Jackson on February 25 are 36º and 14º.
Upcoming Weather Pattern
A spring-like pattern will take hold in the wake of the mid-week storm.
From Thursday to Saturday, dry conditions and increased sunshine can be expected with highs rising well into the 40s in the valley. The small amount of snow cover that remains in the lower valley will continue to melt.
Despite the warmer temperatures, a strong jet stream located further north near the Canada border will be close enough to result in gusty winds each day, especially over the higher elevations.
On Sunday and Monday, a weak storm is projected to move into the Central Rockies, resulting in a chance of snow. This will probably be a lighter snow event for the Tetons, while the valley is looking at rain showers or a rain/snow mix due to warm air in place.
Around the middle of next week, we will likely dry out again with spring-like conditions. Highs will reach the 40s in the valley each day over the next week.
The 7-day snowfall projection below represents the average of 50 simulations of the European Weather Model. And this projection accounts for today’s snowfall on the backside of the recent storm, as well as the light snowfall expected on Sunday-Monday.
Looking further out, the pattern continues to favor above-average temperatures through at least the first 10 days of March.
However, the early part of the month is expected to be relatively unsettled with weather systems sneaking into the area every few days or so. This could be enough to at least freshen up the slopes a little bit at mid to upper elevations on a semi-frequent basis.
Alan Smith, Meteorologist
