JACKSON, Wyo. — We saw a beautiful stretch of sunny weather with mild temperatures during the first half of last week, before the pattern turned more unsettled over the second half of the week and into the weekend.
A storm system last Thursday brought a good soaking rain to the Jackson Hole Valley along with 6-10 inches of new snow above 9,000 feet. Temperatures did not stray far from average for late April with the town of Jackson recording a weekly low of 20 degrees and a weekly high of 59 degrees.
The town of Jackson picked up a half inch of rain last week while valley locations north and west of Jackson received over 0.75 inches. The higher elevations received about 1-2 inches of moisture, including 14 inches of new snow at Jackson Hole’s Rendezvous Plot at 9,580 feet.
Snowpack remains well above average across all elevations of the Tetons with only some minor melting across the mid to high elevations during the past week.
Weekly Weather Outlook – April 27 – May 3
Over the upcoming week, we can expect a significant warm-up which will speed up snowmelt rates and increase the threat for wet slide activity in the mountains. We’ll also see at least a couple of systems bring showery weather to the region, as is typical at this time of year — May is Jackson’s rainiest month on average.
Conditions are starting out dry on Monday morning with mostly cloudy skies, but a system approaching from the west will result in rain showers developing by early afternoon and continuing into the evening hours. A thunderstorm will be possible on Monday afternoon as well.
Here is a look at Monday morning’s satellite and upper atmospheric weather chart, which shows the system approaching from the west.
Highs on Monday will reach the mid 50s in the valley and the rain/snow line will be rather high, ranging from 9,000-10,000 ft. on Monday afternoon. Winds will also become strong out of the west/southwest on Monday afternoons across all elevations.
On Monday evening, a cold front will arrive with scattered showers persisting well into the night and snow levels eventually falling to 7,000-8,000 ft., though some flakes couldn’t be ruled out on the valley floor if any shower activity lingers into early Tuesday morning. Any snow accumulations at the higher elevations on Monday night will be light.
Tuesday is looking nice and sunny with highs warming up into the low 60s, though winds will pick up again during the afternoon out of the west/southwest. A big warm-up will occur on Wednesday as a strong ridge of high pressure builds over the Rockies.
As a result, we’ll see mostly sunny skies and highs reaching the upper 60s to possibly 70 in the valley. The mid-week warmth will accelerate snowmelt and will almost certainly lead to an uptick in wet avalanche activity in the mountains.
On Thursday, the next system will arrive bringing a good chance of rain showers throughout the day with rain falling even at the higher elevations due to warm air in place. On Friday and Saturday, we will dry out more with only a slight chance of showers both days.
Another system is projected to approach late in the weekend. This is almost a week away and a lot can change between now and then, but for now, it appears that shower and thunderstorm chances will increase starting on Sunday, with cooler temperatures and possibly more widespread precipitation next Monday.
Alan Smith, Meteorologist