JACKSON, Wyo. – Subtropical moisture will return to the Tetons this weekend, with light rain showers on Friday and Saturday giving way to heavier showers on Sunday. Snow levels will be above 9,000 feet for most of the weekend, but will drop to pass level or lower by early next week.
Recent Weather
Two weather systems have impacted the Tetons and Jackson Hole over the past week, and average snow levels have gradually been creeping downward, though we’re still waiting on our first measurable snow of the season in the town of Jackson.
The first storm system brought rain and snow to the area from October 22-23 (Friday AM to Saturday AM). Snow levels started out around 10,000 feet before dropping to 8,000 feet on Friday night (closer to 7,000 feet on the west side of the range).
This storm produced 4-7 inches of snow in the Tetons above 9,000 feet and down to 8,000 feet at Targhee, while only 1-2 inches of snow fell down to 8,000 feet on the east side of the range. Most of this new snow melted below 9,500 feet over the weekend.
Rain totals in the valleys ranged from 0.4 to 0.8 inches on October 22-23, including 0.72 inches in the town of Jackson.
Conditions dried out from Saturday to Monday, then the next storm system arrived on Monday night.
This storm was a quick-hitter, but temperatures were also colder, with snow levels dipping to 6,700 feet – low enough to dust the mid to upper slopes of Snow King.
Snow totals ranged from 1-3 inches in the Tetons, but this was enough to cause winter travel issues on Teton Pass for the first time this season, with slick roads contributing to multiple accidents and a brief road closure.
Another weaker disturbance moved through on Tuesday-Tuesday night, bringing some light snow showers and graupel showers with minimal accumulations to most areas. The town of Jackson did see some very light snow and graupel, but it was not measurable.
For the month of October, the town of Jackson has received an impressive 2.84 inches of rain. We will likely come up just short of hitting 3 inches, with only light rain showers expected at the end of the month. Average precipitation in October is 1.75 inches, for perspective.
Despite the wet October, Jackson has yet to receive a measurable snowfall so far this season. The average first measurable snow is October 16, so we are a couple of weeks (and counting) behind schedule.
Here is the 7-day weather summary for the town of Jackson:
For perspective, the average high and low temperatures in Jackson on October 28 are 51º and 23º.
Upcoming Weather Pattern
We are getting a break in the weather pattern for the middle of the week with seasonally chilly temperatures. Highs only reached the upper 40s during the day on Wednesday, but will warm up into the 50s on Thursday afternoon.
Heading into Halloween weekend, a slow-moving cut-off low pressure system will work its way across the Southwest and Southern/Central Rockies, but in close enough proximity to bring more subtropical moisture into our area from the south.
Sound familiar?
This has been a common theme for us this fall, in which we’ve seen wetter-than-average but also warmer-than-average conditions with high snow levels as a result.
Initially, we will see an increase in cloud cover with intermittent light showers on Friday and Saturday as moisture gradually increases. Halloween looks a little wet on Saturday, but not too bad, as the main event holds off until Sunday.
We will see a stronger surge of moisture and energy arrive on Sunday, with heavier and more widespread rain showers possible.
Snow levels will be high for most of the weekend, generally near or above 9,000 feet before a cold front arrives sometime later on Sunday or on Sunday night.
Behind the cold front, snow levels are projected to dip to 7,000 to 8,000 feet by Monday morning, which is low enough for snow to accumulate on Teton Pass, so I would be prepared for possible winter travel impacts on Monday morning.
Based on the latest projections, it’s unlikely that snow levels will reach the lower valley floor, at least around the town of Jackson, on Monday. But we’re also far enough out that it can’t entirely be ruled out yet, as the forecast could still change.
The 7-day precipitation projection below represents the average of 50 simulations of the European Ensemble Model. Notice how the Southwest will be very wet once again, but that we still catch a good amount of moisture on the northern fringe of the storm track.
Starting on Tuesday, it looks like we are going to head into a milder and drier pattern as a ridge of high pressure is expected to become the dominant pattern across the Interior West.
As a result, we may see reduced precipitation (and snow) chances through the first 7-10 days of November. Perhaps a system will manage to sneak in at some point, but overall, the pattern for early November (aside from the first 2 days) looks a bit quieter compared to the past few weeks.
Alan Smith, Meteorologist
