JACKSON, Wyo. – A significant warming trend is underway with high temperatures rising into the low 80s from Thursday through the weekend. Isolated afternoon thunderstorms will also enter the picture on Friday and Saturday, with more numerous storms possible on Sunday and Monday.
Recent Weather
May was a chilly month in Jackson Hole with temperatures running nearly 3ºF below average. On the final day of the month, we had a morning low of 23ºF in Jackson which was the lowest value for so late in the year since 1995 when the temperature dipped to 21ºF on June 7.
We also saw a low of 27ºF on Saturday, June 1 but temperatures have been milder since then. On Sunday, we had a high of 72ºF in town, then a storm system arrived on Monday with steady rain falling throughout the day.
Rainfall amounts were variable, generally ranging from 0.20 to 0.40 inches in the Jackson Hole Valley, including 0.40 inches in East Jackson and 0.34 inches at the climate station near the visitor center.
Rainfall was heavier in the mountains as the Raymer Plot above 9,000 feet received 1.05 inches. The combination of rain and melting snowpack across the higher elevations has resulted in a rise in rivers and streams.
In fact, a Flood Warning is currently in effect for Teton County, Idaho as Trail Creek near Victor experienced flooding in recent days and the Teton River is expected to approach flood stage.
Partly cloudy skies and gusty winds have prevailed in the wake of Monday’s system. This has resulted in mild overnight lows in the 50s in Jackson for each of the past three mornings.
On Wednesday afternoon, the high temperature hit 74ºF in Jackson, making for a comfortable day in the valley and only the fifth day this year with a high of 70ºF or warmer.
Upcoming Weather Pattern
A strong ridge of high pressure is building over the Western U.S. right now, and this will be the culprit for our warm-up that will suddenly make it feel like summer. Wednesday has already been noticeably warmer than recent days, and on Thursday we will see highs reach the 80s in Jackson for the first time this year.
The warmth will hold through the weekend with highs in the low 80s each day through Sunday. Average highs at this time of year are in the upper 60s to low 70s, so we will be running about 10-15 degrees above average.
The Western U.S. will be warmer than average as a whole, with triple-digit heat expected in the deserts and lower valleys of the Southwest and Great Basin.
For the most part, conditions will be ideal for outdoor activities, but we will start to see some afternoon thunderstorm activity enter the equation – something we haven’t experienced much of yet this year.
Learn More ? Thunderstorm Safety
On Friday, a weak disturbance will push through the high pressure ridge with enough moisture and instability in the atmosphere for isolated thunderstorms to develop. A similar pattern is expected on Saturday as well. Any rainfall will be light and spotty with Friday/Saturday storms, but gusty winds and cloud-to-ground lightning will be possible.
On Sunday and Monday, a more potent disturbance will move through, which may result in more numerous thunderstorms along with the potential for downpours. The highest threat of rain and thunderstorms will be during the afternoons, but some overnight and morning showers couldn’t be ruled out either.
Here is a rainfall projection for the next 7 days, representing the average of 50 simulations of the European weather model. This shows that we aren’t expecting a lot of rain over the next week, but that it will not be completely dry either.
Temperatures will cool off slightly on Monday and Tuesday (mid 70s currently projected), but longer-range models are projecting temperatures to warm back up into the 80s during the second half of next week.
Alan Smith, Meteorologist
