One final mild stretch of weather, then winter arrives

JACKSON, Wyo. — We’ve entered a nice stretch of mild and sunny weather after the early season cold blast about a week ago. Enjoy it while it lasts, because winter conditions will return this weekend – and are likely here to stay this time.

After experiencing the coldest October temperatures on record in Jackson last Monday, temperatures rebounded nicely late in the week and into the weekend. Highs rose well into the 50’s in the Jackson Hole valley from Friday, October 30 through Monday, November 2 with sunny skies each day.

Sunny with warmer than average temperatures through Friday

A ridge of high pressure will remain parked over the Western U.S. for the next several days, continuing to result in warm and sunny daytime conditions and seasonally cold nights.

In fact, high temperatures are expected to reach the low 60s in the Jackson Hole Valley from Tuesday through Thursday and the upper 50s on Friday, which is well above average for early November. Enjoy it while it lasts, because we probably won’t see temperatures like this again until April.

5-day temperature anomaly (in Celsius) for Monday, November 2 -Friday, November 6. Source: weathermodels.com

Storm arrives this weekend with snow and much colder temperatures

A more significant pattern change will arrive over the weekend, and unlike our brief but severe cold snap in late October, this one will have staying power.

First, a storm system approaching from the west will impact the Rocky Mountains on Saturday with a sharp cool-down for Jackson Hole along with some snow. Precipitation will likely start as a rain-snow mix in the valley before changing to all snow.

Questions remain as to how much snow potential we have in Jackson Hole. The system as a whole will bring snow to most mountain ranges in the Western U.S. but the exact track of the system and whether or not we see a favorable wind direction remains in question.

For now, this storm looks like more of a “moderate” snow event in the Tetons and not as heavy as our storm in late October, but that could always change given this is still several days out.

Upper atmospheric weather pattern for Saturday, November 7. Source: weathermodels.com

Once snowfall ends sometime on Sunday, confidence is high that very cold air will arrive to follow. In fact, temperatures could run well below average through much of next week (week of November 9-13) with highs struggling to reach the freezing mark in the valley.

Early next week, we may see at least a couple of cold and dry days initially, but then more consistent shots of snow should be anticipated as we head into mid-November as the jet stream sets up in a favorable position for Pacific moisture to spread into the Northern and Central Rockies. In other words, this truly looks like the start of winter and the extended outlook is favorable for base-building snow at the ski resorts.

5-day temperature anomaly for November 8-12. Source: weathermodels.com

October finishes with near-average temperatures and precipitation despite late cold snap

As previously mentioned, Jackson experienced its coldest October temperature on record last week with a low of -9 on October 26. However, as a whole, the month finished with near-average temperatures (at the JH Airport, the average temperature was actually 0.6 degrees above normal) thanks to consistently warm temperatures over the first three weeks of the month.

Western U.S. temperature anomalies for October 2020. Jackson experienced near-average temperatures. Source: High Plains Regional Climate Center

The Town of Jackson weather station had an 84-degree temperature difference between its warmest temperature of the month (75 degrees on October 8) and its coldest temperature of the month (-9 on October 26). While it would take way too long to try to data dig and figure this out, this has to be one of the larger monthly high versus low temperature differences that Jackson has ever experienced.

Precipitation also ended up right around average across Jackson Hole for the month of October. Jackson was essentially right on the dividing line with wetter than average conditions to the north and drier than average conditions to the south.

Western U.S. precipitation anomalies for October 2020. Jackson experienced near-average precipitation. Source: High Plains Regional Climate Center

Thanks for reading, enjoy the last of the warm/sunny days and get ready for the snow to arrive in the coming weeks!

Alan Smith, Meteorologist

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