JACKSON, Wyo. — The first significant weather system in several weeks will impact Western Wyoming this weekend with a mix of rain and wet snow across the lower elevations and heavy snow for the higher elevations.
Thursday will be the last sunny day for a while, then the pattern will start to shift on a Friday as a weak disturbance moves through from the northwest. We will see some light snow showers from this disturbance but it won’t amount to much moisture.
Saturday morning will start out dry with partly to mostly cloudy skies, then showers will arrive from the southwest on Saturday afternoon and evening as the leading edge of the storm system approaches.
Valley rain and mountain snow will become more widespread and heavier on Sunday and into Sunday night, with a changeover to wet snow likely in the valley on Sunday night and Monday morning.
Additional showers can be expected on Monday and Monday night, and temperatures will also be colder. As a result, we will likely see more snow versus rain on the valley floor on Monday.
Rain and Precipitation Amounts
We are still a few days away from this event, but right now it looks like the Tetons will pick up anywhere from 1 to 1.5 inches of precipitation from Saturday through Monday, with upwards of 2 inches not out of the question.
The Jackson Hole Valley should pick up anywhere from a half-inch to an inch of precipitation, with locally higher amounts possible if some of the more aggressive weather models (for this storm) verify.
While the timing of the wet weather over the weekend will be a drag for outdoor activities, we really need this moisture given how dry the pattern has been since the beginning of March.
So far in April, the weather station in the town of Jackson has received only 0.12 inches of precipitation and the weather station near Jackson Lake has received only 0.35 inches of precipitation. Average precipitation for the month of April is 1.28 inches in Jackson and 2.04 inches at Jackson Lake, so we are well behind.
Looking back further, Jackson has only received 0.24 inches of precipitation since March 1 and Jackson Lake has only received 0.80 inches.
Snow Levels and Snow Amounts
As is often the case with a late April storm system, snow levels will fluctuate quite a bit.
On Saturday afternoon, snow levels will range from 7,000-8,000 feet, then will fall to around 6,500 feet on Sunday morning with valley areas waking up to a mix of rain and wet snow.
Snow levels will then rise to 7,000-7,500 feet on Sunday with all rain for most of the valley. On Sunday night, colder air will arrive with snow levels dropping to the valley floor.
In fact, most of the valley including the Town of Jackson could wake up to some slushy snow accumulations on Monday morning.
The higher elevations of the Tetons above 8,000 feet will pick up around 6-12 inches of snow from Saturday through Monday. There may be a little bit of snow covering the top of Teton Pass on Sunday morning, but the most impactful commute over the pass will be on Monday morning with heavier/slushy accumulations likely.
Thunderstorms
Believe it or not, there is at least a chance we could see thunderstorms across Teton County and Northwest Wyoming on Saturday afternoon in response to weak atmospheric instability along with a surge of energy arriving from the southwest. This is just a sign of the change of seasons as we head later into spring.
Temperatures
Ever since the warm-up that occurred during the first five days of April, temperatures have been consistently below average during the two plus weeks since despite the lack of significant moisture.
With more widespread and heavier precipitation arriving, temperatures will remain on the cooler side of average through the weekend with valley highs in the low 50s on Friday and Saturday and 40s on Sunday and Monday. Average highs for this time of year are in the mid to upper 50s.
Medium to Long Range Outlook
On Tuesday, we’ll start to transition out of the wet pattern but some lingering clouds and light (snow) showers will remain possible along with colder than average temperatures.
Dry and sunny weather should return on Wednesday and persist for a couple of days along with warmer temperatures. However, long range signals indicate we could head back into a cooler and wetter pattern during the first few days of May.
Alan Smith, Meteorologist
