JACKSON, Wyo. – The first stretch of spring-like warmth has taken hold across Teton County during the past several days. However, we will revert back to a cooler and more unsettled pattern over the next week, including several shots of snow for the higher terrain.
First major warm-up of the spring
It has been a long, cold and snowy winter in the Tetons, and the recent stretch of warm and dry weather has been a welcome occurrence for many.
Jackson ended its 157-day streak of high temperatures below 50 degrees on April 8. This was one of the longest such streaks on record, coming up just short of the all-time record sub-50-degree streak of 162 days in 1935-1936.
Temperatures were even warmer early this week with the high temperature in Jackson reaching 58ºF on Monday and 65ºF on Tuesday. The 65ºF reading on Tuesday was the warmest temperature we have seen since October 20.
Temperatures have also been warm in the Tetons with highs reaching the upper 40s to low 50s at the 8,000-9,500 foot level on Tuesday. Low temperatures above the valley floor have been above freezing on the past two mornings as well, which has led to an uptick in wet avalanche danger.
Despite the recent warm-up, temperatures are still running 5.5ºF below normal so far this month thanks to unseasonably cold temperatures during the first week of April.
For perspective, the average high in Jackson in mid-April is 54ºF and the average low is 25ºF.
Snowpack Update
Snowpack remains well-above-average across the region despite the warmer temperatures experienced in recent days. Currently, snowpack is 122% of average in the Upper Snake River Basin, as measured by the water content of the snowpack.
The snowpack has dipped slightly after peaking on April 8. However, colder and more unsettled weather over the next 7-10 days will slow the rate of snowmelt across the higher elevations, and depending on how much snow falls, we may even see some brief gains to the snowpack that could temporarily bump us above the previous peak on April 8.
Snowpack remains above average throughout the state of Wyoming as well.
Here is a look at current snow depths (the amount of snow on the ground) from roughly west to east across the Greater Teton-Jackson Hole region.
The snow depth of 15 inches in the Town of Jackson is tied with 2008 for the deepest on record for April 12. The snow depth in town has decreased by 10 inches since this time last week due to snowmelt from our recent warm spell, but we still have a little ways to go before completely melting out.
Cooler and more unsettled weather returns
Spring is a season of transition and fluctuations between warm/sunny weather and cool/wet/snowy weather is common in the Tetons. This will certainly be the case over the next week.
On Wednesday, we are already seeing a shift to more unsettled weather as a storm system approaches from the Pacific Northwest. We are seeing an increase in cloud cover along with scattered light showers, mainly over the higher elevations.
Shower activity will become more widespread later Wednesday night as the center of the storm system approaches, and a cold front will also move through early on Thursday morning.
Snow levels (i.e. the rain/snow line) will start out as high as 8,000-9,000 feet on Wednesday afternoon, before lowering to 7,000-8,000 feet on Wednesday evening, and eventually falling to the valley floor by Thursday morning.
A period of heavier snow is expected through the morning hours on Thursday, which will impact the commute over Teton Pass. Snowfall will then become more showery in nature on Thursday afternoon and evening, but temperatures will be noticeably colder with highs in the mid/upper 30s in the valley along with brisk west/southwest winds.
Snow totals from Wednesday night through Thursday night will range from 4-8 inches in the Tetons above 8,000 feet, and snow quality will be wet and heavy.
The Jackson Hole Valley could pick up anywhere from a trace to 2 inches of snow on Thursday morning depending on snowfall rates as temperatures will be borderline in the low 30s. The valley may get by with only wet roads on Thursday morning unless snowfall rates are intense enough to overcome the warm pavement, in which case slushy road accumulations will be possible.
After this storm, cool and unsettled weather will persist on Friday as a trailing weak disturbance moves through. Light snow showers will redevelop with a couple of inches possible up high, while the valley should only see a light dusting at best. Highs in the valley will reach the upper 30s on Friday.
A return to dry and sunny conditions will occur this weekend as a ridge of high pressure builds over the Central Rockies. If you plan on heading over to Grand Targhee for their closing weekend, you can expect a return to spring skiing conditions.
Highs on Saturday will reach the mid 40s in the valley before warming up into the mid 50s on Sunday. Hard freezes are excepted in both the valley and the mountains on Saturday and Sunday mornings.
Following the weekend break, a slow-moving low pressure system will approach from the Northwest early next week (approximately the Monday-Wednesday timeframe), resulting in a return to cooler and more unsettled weather.
Extended Outlook
Generally speaking, the pattern during the second half of next week (and possibly beyond) continues to look cool and unsettled with below-average temperatures for late April.
The higher elevations will continue to see snow showers on a relatively frequent basis, while the valley will likely see periods of rain and snow showers with gradual melting of the low-elevation snowpack.
Alan Smith, Meteorologist
Note: I will be traveling in late April so this will be my last weather article for the next couple of weeks. Stay tuned for the next article on Wednesday, May 3.
