Heavy rain, strong winds expected Monday with falling snow levels on Monday night

JACKSON, Wyo. – A powerful storm system remains on track to impact Jackson Hole on Monday with heavy rain, strong winds and mild Pacific air as an atmospheric river takes aim at Northwest Wyoming.

Snow levels will be high for much of this event due to the mild air in place, but a cold front will arrive early Monday evening with snow levels falling behind the front through Monday night. Colder and unsettled conditions will continue on Tuesday and Wednesday with additional snow showers along with low snow levels.

Timing of the Storm

Showers will arrive late afternoon or early evening on Sunday and will continue at light to moderate intensity through Sunday night. Snow levels will quickly rise on Sunday night as milder air floods into Jackson Hole from the south. Snow levels overnight will generally range from 9,500-10,500 feet, possibly higher at times.

On Monday, precipitation will continue to pick up in coverage and intensity throughout the day with snow levels remaining high in the 9,500-10,500 foot range. Winds will also be very strong over the higher elevations.

A cold front will arrive late afternoon or early evening Monday, and behind the front, snow levels will fall. A few hours of heavy precipitation is likely in advance of and behind the front, before tapering off to lighter precipitation late Monday night. Snow levels will fall to the valley floor by Tuesday morning.

An active west/northwest flow will continue behind the main system on Tuesday and Wednesday with a series of weaker disturbances resulting in continued snow showers. This activity will be less intense compared to Monday’s storm, but temperatures will also be colder.

Snow levels will be on the valley floor during the day on Tuesday, but we could see rain start to mix in with snow again on the valley floor by Wednesday afternoon as temperatures gradually start to warm.

Rain/Precipitation Amounts

Rainfall and liquid-equivalent precipitation will range from 1.25 to 2.5 inches over the Tetons from Sunday night through Tuesday morning and 0.65 to 1.5 inches over the Jackson Hole Valley.

Additional liquid-equivalent precipitation on Tuesday and Wednesday will range from 0.5 to 1.0 inch in the Tetons and 0.1 to 0.4 inches in the Jackson Hole Valley.

Snowfall Amounts

Due to the timing of the warm air and heavy precipitation, snowfall amounts are not looking as impressive as they once did, unless you’re talking about areas above 10,500 feet (which will also be heavily wind-affected).

Snowfall on Monday night will range from 3-7 inches between 9,000-10,000 feet in the Tetons and 1-3 inches between 7,500-9,000 feet. Areas below 7,500 feet and down to the valley floor will see minimal accumulations. The snow that accumulates on Monday night will be very wet and dense (i.e. “Sierra cement”).

Additional snowfall later this week will range from 2-5 inches above 8,000 feet on Tuesday and 1-3 inches above 8,000 feet on Wednesday. Any accumulations on the valley floor will likely be minor and short-lived.

In the town of Jackson itself, borderline temperatures (see the chart below) will mean that snow will have trouble accumulating. If we do see any accumulations, it would likely happen during the early morning hours during any heavier bursts of snow showers when temperatures are at their lowest and heavy snowfall rates could overcome the warm surface.

Wind Impacts

Winds will be very strong during the storm on Monday over the higher elevations, out of the south/southwest with gusts to 75 mph possible over 10,000 feet and gusts to 40-50 mph between 8,000-9,000 feet.

In the valley, we could see gusts out of the south in the 20-30 mph on Monday afternoon.

Winds will be lighter on Tuesday, but are expected to pick up again during Wednesday’s disturbance with gusts to 50-60 mph out of the west at 10,000 feet and 20-25 mph out of the southwest in the valley.

Extended Range Outlook

Another weak disturbance could arrive from the northwest on Thursday, but warmer air will also be arriving with rising snow levels.

We should dry out on Friday, then another disturbance is possible on Saturday with snow levels projected to be relatively high.

A drying trend with mild temperatures is then expected starting around Halloween and continuing into the first few days of November.

Alan Smith, Meteorologist

 

 

About The Author

Buckrail Meteorologist Alan Smith

Alan is a professional meteorologist who holds a degree from MSU Denver and writes weather forecasts for Buckrail. He has worked in the private sector of weather forecasting since 2013 and has lived in Jackson since 2015. Alan specializes in mountain weather and forecasts for ski areas across North America.

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