JACKSON, Wyo. — We’re in the midst of a warm and beautiful fall weather pattern, which will continue through the middle of this week. The next storm system will arrive on Thursday, with showers, thunderstorms and decent rainfall totals expected, but snow levels will remain high when most of the precipitation falls due to mild temperatures in place.

September 20-26 Recap

Last week started out warm and dry before a storm system arrived on Wednesday, producing widespread showers and thunderstorms followed by cooler temperatures and lingering showers on Thursday.

Snow levels were relatively high during most of this event as the moisture arriving was subtropical in nature. However, as cooler air arrived on Thursday, snow levels dipped to around 10,000 feet, but snow that fell quickly melted off in most areas, except for shaded terrain on the highest peaks.

The Town of Jackson received 0.62 inches of rain last week, all of which fell between Wednesday afternoon and Thursday afternoon. Elsewhere, Moran picked up 0.72 inches of rain while radar estimates indicate the Tetons likely received between 0.75 and 1.50 inches of rain.

Following last week’s storm system, conditions quickly cleared out from Friday through Monday with outstanding fall weather.

High temperatures last week ranged from 57ºF on September 22 to 79ºF on September 26 and low temperatures ranged from 29ºF on September 24 to 43ºF on September 23. Other than Thursday and Friday, temperatures were warmer than average for this time of year for most of last week.

Forecast for Tuesday (9/27) to Monday (10/3)

Warm and dry conditions will continue for two more days on Tuesday and Wednesday as a ridge of high pressure remains in place over the Western U.S. Highs will reach the upper 70s in the valley on both days, which is above average for the end of September. Mostly sunny skies and light winds can also be expected on both days.

On Thursday, the next storm system will arrive, resulting in off-and-on showers from early Thursday morning through Thursday evening along with gusty southwest winds. Thunderstorms will also be possible in the afternoon. This system does not look as strong as last week’s system, but decent rainfall amounts will still be possible.

The warm airmass in place as this system arrives will also result in high snow levels on Thursday, ranging from 11,000-12,000 feet.

On Friday, lingering moisture will result in additional scattered showers, but coverage and amounts will be less compared to Thursday. A cold front will also arrive early Friday, and this will result in snow levels lowering to the 8,500-10,000 foot range. However, any accumulations down to these elevations will be on the lighter side and will melt off in the days to follow.

In the valley, highs will reach the upper 60s on Thursday and the upper 50s on Friday.

On Saturday, the slow-moving storm system will move east of the area, but we will likely continue to see some cloud cover. However, easterly winds will favor only light showers/sprinkles if anything so it will be a relatively dry day. Temperatures will remain on the cooler side, however, with highs near 60 in the valley.

East of Jackson Hole, heavier precipitation including snow is possible in the Absaroka and Wind River Ranges on Friday night and Saturday, so heads up if you are heading out that way.

On Sunday, we will start to dry out more though a few sprinkles (and high elevation flurries) couldn’t entirely be ruled out if that last storm system hangs around east of here for longer than expected. Highs are currently expected to reach the mid 60s in the valley.

On Monday, further drying is expected along with mostly sunny skies and highs in the upper 60s – signaling another stretch of near-perfect fall weather.

Extended Outlook

Dry and sunny conditions are likely through the first half of next week with a ridge of high pressure in place across the Western U.S. Highs should top out in the upper 60s to low 70s through mid-week based on medium to long-range projections.

Over the second half of next week, it’s possible we could see a weaker disturbance or two arrive with occasional showers possible. However, the pattern does not look conducive to major storm systems at this time. Temperatures will fluctuate depending on if and when any disturbances arrive, but overall, early October is looking warmer than average.

Note: I will be on vacation during the first two weeks of October and will not be posting weather updates during this time. The next weekly weather update will be posted on October 17 or 18.

Alan Smith, Meteorologist

Town of Jackson Climatology for September 20-26:

Average High: 66

Average Low: 28

Record High: 87 (October 1, 1997)

Record Low: 9 (September 30, 1985 and October 1, 1950)

Precipitation Since Oct 1st: 17.93″ (104% of Average)

Buckrail Meteorologist Alan Smith

Alan is a professional meteorologist who holds a degree from MSU Denver and writes weather forecasts for Buckrail. He has worked in the private sector of weather forecasting since 2013 and has lived in Jackson since 2015. Alan specializes in mountain weather and forecasts for ski areas across North America.