JACKSON, Wyo. – We’re coming out of another active weather period across Northwest Wyoming with numerous thunderstorms and abundant rainfall over the past several days, along with a dip in temperatures. However, over the rest of this week and into next week, we will see our first real extended stretch of summer-like weather.
June 14-20 Recap
The Tetons and Jackson Hole continued into the early part of this week.
We’ve been in a weekly cycle featuring active weekend weather for quite some time now. In case you’re wondering, Jackson has received a measurable rainfall at least one day every weekend (Saturday or Sunday) since the beginning of May.
Last week started out like the floods in Yellowstone and severe thunderstorm wind damage around Jackson Hole. However, we have seen our warmest temperatures of the year so later in the week with highs in the 80s.
Conditions turned unsettled and also very windy over the weekend as a result of thunderstorms (and a fantastic lightning show) over the Tetons on Friday night followed by clouds, gusty winds, and isolated showers on Saturday .
Conditions then turned wet on Sunday as a series of heavy thunderstorms moved through the south, starting on Sunday morning and continuing into Sunday evening.
A cold front also arrived on Sunday with much cooler temperatures. Periods of showers and thunderstorms continued to move through on Monday and light snow above 8,000 feet with the Tetons revealing dustings of snow during breaks between showers / storms.
A funnel cloud was also observed near Driggs / Tetonia on Monday, or more specifically a “cold air funnel”. Cold temperatures Winds near the surface and aloft can differ enough in this post-frontal armass to result in rotation, allowing a funnel cloud to form. Cold air funnels are usually harmless and rarely ever reach the ground.
The Jackson weather station received 0.59 inches of rain over the past week, Throughout Teton County and Yellowstone, generally ranging from a half-inch to three inches of rainfall, possibly approaching an inch across some of the higher elevation areas.
This is a very important week after the last week.
Temperatures were all over the place during the past week with three days of highs in the 50s in Jackson, one day with a high in the 60s, and three days with highs in the 80s.
High temperatures ranged from 53ºF on June 14 to 86ºF on June 17, and low temperatures ranged from 30ºF on June 16 to 47ºF on June 19.
Forecast for Tuesday (6/21) to Monday (6/27)
We got a nice taste of summer late last week, but it will arrive for real this week with no significant cool snaps on the horizon.
Tuesday morning is starting out chilly with areas of fog and low clouds. However, this low cloud cover will quickly turn out to be a beautiful day with highs reaching the low 70s in the valley under sunny skies. Winds will also be light for a change.
Temperatures will start out freezing in the valley on Wednesday but will warm up quickly with highs in the upper 70s under mostly sunny skies. Winds will pick up a bit out of the southwest during the afternoon, but overall, it looks like a wonderful day to get outside.
The North American Monsoon (which is much earlier than usual) attempts to work its way into the Tetons from the southwest.
Thursday will be warmer with highs in the low 80s along with a breezy afternoon afternoon, but isolated thunderstorms will become possible later in the afternoon and into the evening. Isolated showers will remain possible overnight, but any rainfall will be light and spotty.
Friday is more uncertain as a disturbance will be passing from the north at some point.
Depending on the northward / southward extent of the disturbance and timing of the cold front, moisture could increase ahead of the front to the uptick in showers or thunderstorms. Or, the cold front could arrive early enough to push the moisture southward and keep us dry.
Weather models are in poor agreement on how Friday’s pattern will play out, but we can expect a small chance for showers on Friday morning and a better chance of showers / thunderstorms on Friday afternoon. Rainfall amounts should be light overall, and temperatures will cool off into the 70s for highs with breezy winds also expected.
This weekend is looking quite nice as drier will be arriving behind friday’s cold front. Highs on Saturday will reach the mid 70s in the valley and winds are likely to be stronger in the wake of Friday’s disturbance. However, a thunderstorm is likely to develop with higher elevations.
On Sunday, we will see slight warmer temperatures with highs near 80 to mostly cloudy skies. Thunderstorm may increase on Sunday afternoon compared to Saturday, but activity looks fairly isolated at this time with any storms producing only light rain.
Monsoonal moisture will increase over the Great Basin this weekend and is likely to lead to the Tetons on Monday afternoon. . Northwest winds are less favorable for storms to “survive” upon reaching the valley, with a greater chance of storms over the Northern JH Valley compared to town. However, we’re still far enough out that the details could change.
Temperatures with relatively frequent afternoon thunderstorms from time to time.
Overall, temperatures are expected to be above average for the next week with highs getting into the 80s in the valley most days. Thunderstorm and rain chances will fluctuate from day to day.
Alan Smith, Meteorologist
Town of Jackson Climatology for June 21-27
Average High: 77
Average Low: 38
Record High: 95 (June 26, 1988)
Record Low: 22 (June 25, 1953)
Precip 24-Hour Record: 0.85 ″ (June 26, 1965)