We had quite a start to the week with heavy snow showers and cold temperatures on Monday, followed by a slight warm-up but still overall chilly conditions with isolated snow showers on Tuesday.

Jackson Hole's upper mountain above 9,000 feet picked up 5 inches of new snow on Monday while the valley was coated with wet snowfall off and on during the day as heavy snow showers moved through. Jackson only recorded a high of 35 on Monday, which was a record "low maximum" for the date.

Wednesday has turned out to be a pretty nice day following a chilly start with mostly sunny to partly cloudy skies. Jackson has seen a high temperature of 61, which is much closer to average for this time of year.

Forecast for Wednesday Night - Thursday:

Currently (as of late Wednesday afternoon), a trough of low pressure is located over the Great Basin. This trough will lift northeastward into Central Wyoming overnight with rain/snow showers and thunderstorms developing east of the Continental Divide initially.

The center of low pressure will deepen over North Central Wyoming early Thursday morning and moisture wrapping around the center of the low will work its way into the Tetons from the Northwest, resulting in showers developing during the morning hours and continuing off and on through much of the day on Thursday.

There is still some uncertainty as to how much moisture makes it into the Tetons, but overall, models have trended wetter since my last post. With the main flow out of the west/northwest, we will likely see a shadowing effect downwind of the Tetons in the lower Jackson Hole Valley (around town) where showers are likely to be lighter and more spotty in nature.

Temperatures will be noticeably colder on Thursday with gusty winds also expected. Snow levels will be hovering close to the valley floor with a mix of snow and rain showers expected in the valley. Areas above 7-8k feet will likely pick up a few inches or more of snow.

I also wouldn't rule out an isolated thunderstorm on Thursday afternoon, though the overall threat looks low.

Forecast for Friday:

After a brief lull on Thursday evening, another storm system approaching from the west will lead to snow and rain showers developing again by early Friday morning and continuing off and on through much of the day Friday.

Snow levels will likely hover near the valley floor once again with a mix of snow and rain showers expected in the valley, while precipitation will remain all-snow in the mountains where additional light accumulations are expected.

Forecast for Saturday:

Originally, Saturday was looking dry but that is no longer the case. A trailing disturbance will approach from the Pacific Northwest with yet another round of showers now expected during the daytime hours Saturday.

Models are in relatively poor agreement in terms of precipitation potential as there is quite a spread in projected amounts. To me, the overall pattern looks more conducive to a light event versus a heavy event. Still, it will be something to watch over the coming days.

Warmer air will be arriving with this system on Saturday, and as a result, we will see a change-over to all rain in the valley with snow levels projected to rise to around 8,000 feet. There will also be a slightly better chance of seeing an afternoon thunderstorm compared to prior days. 

We should start to see a drying trend by Saturday evening with decreasing clouds on Saturday night.

Here are the projected precipitation amounts across Wyoming and surrounding areas from Wednesday night through Saturday night. This blend of weather models is projecting liquid precipitation totals of a half-inch to an inch across the Tetons during this timeframe.

Forecast for Sunday:

Believe it or not, Sunday continues to look like a warm, dry, and sunny day as high pressure builds in from the south. This will likely be our warmest day of the year so far with highs in the JH Valley projected to reach the upper 60s, and 70 isn't out of the question either. It's been a cold spring, so get out and enjoy!

Next week's pattern has trended more active since my last post with warm temperatures to start the week followed by colder temperatures late in the week.

On Monday, temperatures will be similar to Sunday but a disturbance approaching from the West will result in a chance of afternoon showers and thunderstorms. Tuesday looks like a similar story with mild if not slightly cooler temps along with afternoon showers/thunderstorms.

Temperatures will be warm enough early next week that snow levels will be very high (11,000+ feet). 

Over the second half of next week, a colder and deeper trough of low pressure is likely to work its way into the Western U.S. As a result, shower chances will continue nearly every day through the end of next week with a cooldown also likely late in the week.

By next Thursday (5/19) or Friday (5/20), we will see increasing potential for mountain snow, and eventually, we could even see snowflakes reaching the valley floor. In other words, our cold spring pattern is on track to resume heading into the back half of May.

Thanks so much for reading! Next update on Friday (5/13).

ALAN SMITH