JACKSON, Wyo. – A storm system moving across the Northern Rockies will bring periods of rain and snow to the Tetons and Yellowstone from Wednesday afternoon through Thursday afternoon along with below-average temperatures. Showers are also possible on Saturday and Sunday followed by a warming and drying trend on Monday.
Current and Upcoming Weather Pattern
A potent trough of low pressure will move across the Northern Rockies on Wednesday and Thursday. The heaviest precipitation with this low pressure system will occur across Central Idaho and Southern Montana, but the Tetons and Yellowstone will still pick up some decent moisture on the southern fringe of the system.
Wednesday has been cool and cloudy with off-and-on showers, mainly over the higher terrain of the Tetons. It has not been easy to track the precipitation so far as the closest radar site to our area in Pocatello is currently down for maintenance this week. So if your radar app looks suspiciously clear, then that is why.
A cold front will move through the area on Wednesday night, and rain and snow will become heavier and more widespread during the evening as the front approaches. Snow levels will start out around 8,000 feet, but will quickly fall behind the front.
Once the front passes through, showers will become more scattered and terrain-driven in nature from late Wednesday night through Thursday, while the valleys will see only light and intermittent showers.
However, snow levels will drop to the valley floor by Thursday morning, so Jackson, Driggs, and Victor could all see snow falling at times though accumulations are unlikely. High temperatures on Thursday afternoon will only reach the low to mid 40s, which is about 20 degrees below average for late May.
The higher terrain of the Tetons (above 8,000 feet) can expect a general 4-10 inches of new snow from Wednesday evening through Thursday afternoon along with gusty winds. Slick and slushy roads are possible near the top of the pass on Thursday morning, which could make for a slow commute.
Lingering showers will taper off on Thursday night, and we will see a break in the pattern on Friday with partly cloudy skies and highs in the upper 50s in the valley.
Another storm system will move into the area on Saturday, though this storm looks less organized and weather models are in poor agreement with how heavy or widespread the precipitation will be. At the very least, scattered showers can be expected and temperatures will not be quite as cold with snow levels projected to range from 8,000-9,000 feet.
Sunday is a wild card day as some models are projecting dry conditions to quickly take hold, while others have enough moisture lingering for a chance of showers. For now, plan on a slight chance of showers but with more favorable conditions compared to Saturday.
The holiday weekend will end on a high note on Monday as high pressure builds into the area, resulting in mostly sunny skies and dry conditions with highs warming up into the 60s.
Heading into the middle part of next week, the dry and sunny pattern will continue with highs reaching the 70s.
Here is a precipitation projection for the next week, representing the average of 50 simulations of the European weather model. Heavier precipitation (rain and snow) is expected in Montana with moderate precipitation for the Tetons and Yellowstone, and nearly all of this will fall between Wednesday and Sunday (if not Saturday).
Weather So Far This Month
We are three weeks into May, and so far this month has been cooler than average but also a little bit drier than average. Snowfall, however, has been above average.
Temperatures are running about 3ºF below average this month in the Jackson Hole Valley. In the town of Jackson, we have only hit 70ºF once so far this month. By this date last year, we had already hit 70ºF eight times.
The first week of May was very active and cold with several accumulating snow events in the valley, while the higher terrain received significant snow totals.
The town of Jackson has received 7.6 inches of snow this month, which is well above the May average of 0.6 inches and also makes this “officially” the snowiest May in town since 1973 (caveat: there are many years with missing snowfall data in May).
The Rendezvous Bowl Plot at 9,580 feet in the Tetons has received 41 inches of snowfall this month, which is above its monthly average of 30 inches. More snow is in the forecast at this location over the coming days as well.
May snowfall records at the Rendezvous Bowl Plot only go back to 2008, but in that time span, the May snowfall record is 58 inches which was set in 2011.
Despite the snowy start to May, dry weather since the first week of May along with more seasonal temperatures have resulted in steady snowmelt. Snowpack is now slightly below average for the date in the Tetons, but not by much.
The town of Jackson has received 1.39 inches of precipitation so far this month and the Jackson Lake weather station 1.53 inches. We are on pace to finish with below-average precipitation this month, even with rain and snow in the forecast over the next few days. Average precipitation in Jackson during the month of May is 2.12 inches.
However, water year precipitation (since October 1) has been near normal in our region on the heels of a healthy water year in 2022-2023. As a result, we are currently in good shape from a drought and water perspective, though it wouldn’t hurt if we saw some decent rainfall in June before our climatological driest month of the season in July.
Alan Smith, Meteorologist
