Recent Weather and Current Conditions:

We're coming out of a beautiful weekend that featured abundant sunshine and our warmest temperatures in almost six months. 

Highs rose well into the 60s in the valleys from Friday to Sunday, including highs of 67º in Jackson and Driggs on Saturday. Temperatures also reached the 50s at 8-9k feet and low to mid 40s at the top of the tram at 10,000 feet.

Spring skiing was in full effect for JHMR's closing weekend. JHMR finishes the season with 447 inches of total snowfall at the Rendezvous Bowl Plot and 319 inches at mid-mountain. This turned out to be a solid season overall, with an impressive mid to late-season turnaround following a slow start.

Targhee is still open for another week and I will have a full winter season recap for the Tetons on Friday.

Similar to recent years, I'll continue to post updates a few times per week through the summer months during hiking/climbing season, with occasional breaks whenever I'm traveling.

Forecast for Monday:

We have already seen an uptick in cloud cover on Monday morning with some slight cooling in the Tetons. After a few days in a row without an overnight freeze, low temps are in the upper 20s to low 30s in the mountains on Monday AM while the valleys are above freezing as we do not have a morning inversion in place.

Snow will not soften up as quickly compared to recent days, but temperatures will still be mild enough for softening to occur. Highs are projected to reach the upper 30s at 9,000 feet and low 50s in the valleys under partly to mostly cloudy skies (occasional sun peeking through).

The culprit for our cloud cover increase is a cut-off low pressure system passing to our south across Utah and Colorado. Winds are blowing in a counterclockwise (cyclonic) direction around this low, spreading moisture into our area from the southeast.

East to southeast winds are not a favorable direction for precipitation in the Tetons. So far, we are just seeing some clouds as a result with minimal shower activity. 

However, the potential for scattered showers will increase by the afternoon and evening. We will have convective instability to work with today due to colder air moving in aloft while temperatures will be relatively warm across the lower levels of the atmosphere. 

As the atmosphere becomes unstable on Monday afternoon with daytime heating, scattered showers and thunderstorms will develop across NW Wyoming. Convection can sometimes overcome an unfavorable wind direction, so we may see some of this activity develop over the JH Valley, Gros Ventres, and Eastern Tetons initially.

A shortwave is expected to move through late afternoon/early evening with winds shifting from east to northwest.

This feature will result in a better chance of showers/thunderstorms. Activity will still be scattered in nature, and once the wind shift occurs, the best chance of showers/thunderstorms will be over Teton Valley, and the west side and upper east side of the Teton Range.

Our point forecast for Teton Pass shows the highest lightning potential between about 3pm and 8pm. You can find hourly lightning forecasts by switching from the Snow Summary tab to the Weather tab at the top of the page.

The NWS Storm Prediction Center has a product that calculates thunderstorm/lightning percentage for 24-hour periods based on a blend of high-resolution models. This product indicates a 60% chance of lightning across Teton County, which is a pretty strong signal for mid-April. Just a sign that the seasons are changing.

If you plan on being outside on Monday afternoon, keep an eye out for towering cumulus clouds and dark cloud bases which could signal a building or approaching thunderstorm. In addition, any thunderstorms that develop could produce small hail and gusty winds along with brief downpours.

While temperatures will be cooler on Monday compared to recent days, snow levels are going to be around 9,000 feet on Monday afternoon and evening. So any snowfall will be confined to the higher terrain, with accumulations of an inch or two possible in areas that see showers (activity will be spotty in nature).

Here is a projection from a blend of weather models. Note that higher amounts are forecast along and east of the Continental Divide in the Winds, Absorakas, and Bighorns, as these areas will benefit from east/southeast winds.

In terms of precipitation (rain and liquid-equivalent snowfall), most mountain ranges in Wyoming will see some moisture with heavier amounts expected in Southeast Wyoming.

Forecast for Tuesday:

We will see a lull in the pattern during the day with partly cloudy skies and cooler temperatures. Highs will range from the mid 30s (9,000 feet) to near 50 in the valleys. Winds will pick up in the afternoon out of the west/southwest with gusts to 30-40 mph at 10,000 feet.

We will still see spring conditions with softer snow in the afternoon, but snow may not soften up as quickly due to cooler temperatures and gusty winds.

Forecast for Tuesday Night to Wednesday:

This is when we will see our best chance of accumulating snow in the Tetons. A cold front will work its way southward on Tuesday night and into Wednesday morning with snow showers developing over the Tetons as snow levels lower to near the valley floor (however, accumulations are unlikely in the valley).

The jet stream is expected to set up along/just south of the Wyoming/Montana border. Also, the center of low pressure with this system will be moving into Saskatchewan with northwest winds wrapping around the low and upper-level support from the jet stream favoring the Beartooth and Bighorn Ranges for the heaviest snowfall.

We will be on the southern fringe of the jet stream and are only expected to see light snow totals as a result. I'm expecting Targhee and Teton Pass to pick up 2-4 inches of new snow from late Tuesday night through Wednesday afternoon.

If the jet stream were to set up in a slightly more favorable position than currently expected, then there is an outside chance we could see some heavier snowfall bands develop in the Tetons with low-end potential for 6+ inches at Targhee.

The "most likely scenario" would only result in dust-on-crust skiing conditions in the Tetons, whereas the "low probability boom scenario" of 6+ inches could result in some fun late-season powder turns. 

Temperatures will be much colder on Wednesday after the front passes through with lows in the low 20s and highs in the upper 20s at 9,000 feet.

Valleys will see temps fall into the low to mid 30s on Wednesday morning with afternoon highs in the low 40s. Precipitation will fall as snow in the valleys but will probably not accumulate unless we see temps drop more than expected early on Wednesday morning in which case light/slushy accumulations would be possible.

Winds will become very strong with the frontal passage early on Wednesday morning out of the west/southwest with gusts to 50-60 mph possible at 10,000 feet. Behind the front, winds will remain out of the west/southwest during the day on Wednesday with gusts to 30-40 mph at 10,000 feet.

Forecast for Thursday:

The storm will be moving east, but the tail end of the jet stream will linger over Northern Wyoming, and this could help to trigger some additional showers – especially on Thursday afternoon when the atmosphere is less stable.

Snow levels will remain near the valley floor with a chilly airmass in place, but any snow is expected to be light and confined to areas above 7,000 feet with anywhere from a trace to a couple of inches possible.

 

Outlook for Friday to Sunday (Targhee Closing Weekend)

The overall trend will be toward a warmer and drier pattern, but I wouldn't entirely rule out some showers yet. The American GFS Model indicates a weak disturbance or two arriving from the northwest that could lead to scattered clouds and possibly some showers.

Most other models have high pressure over the Rockies extending further east, which would lead to drier and "sunnier" conditions.

Temperatures are expected to warm up regardless of shower chances, though the extent of the warming is a little uncertain at this time. Our model-blended forecast currently has highs reaching the 40s in the mountains and 50s to possibly low 60s in the valleys.

Bottom line – Spring conditions are likely for Targhee's closing weekend, but I wouldn't rule out some occasional clouds or showers.

Outlook for Monday (April 22) and Beyond:

A mild pattern is expected to persist into early next week. We may eventually see an increase in shower potential heading into late April, but the pattern doesn't look conducive to major cooldowns or late-season winter storms at this time. But this is also a volatile time of year, so that could always change.

Thanks so much for reading! Next update on Wednesday (April 17).

Alan Smith 

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Important Dates:

Snow King – CLOSED for the season (open for uphill access)

Jackson Hole Mountain Resort – CLOSED for the season (no uphill access)

Grand Targhee – Closing Day April 21

Grand Teton Park Road – Open for bike and foot traffic, closed to cars until May 1

Static Peak and Other Winter Wildlife Closures – in effect until May 1