Smoke Outlook:

It's hard to believe we're talking about smoke in mid-May, but here we are. While the Western U.S. had a big winter, Western Canada (especially Northern Canada) was drier than average this winter, and late April and May have been exceptionally warm with record temperatures. The result has been an early outbreak of large wildfires, especially in Northern Alberta.

A ridge of high pressure has been centered over far Western North America this week, but the ridge has shifted slightly further west recently, allowing a cold front to slide into the Central Rockies and adjacent plains from the north on Thursday.

The resulting wind shift from westerly to northerly has allowed heavy smoke to work its way into the U.S. Rockies. Check out the satellite image from about midday on Friday, where you can clearly see smoke blanketing the entire state of Wyoming.

You can also see the extent of the smoke coverage using our smoke maps:

Air quality quickly plummeted when the smoke arrived on Thursday, and since then we have been in the At-Risk or "Unhealthy for Sensitive Groups" range, spoiling what would otherwise be a nice day outside. 

How long will this smoke stick around?

Winds will generally remain out of the north on Saturday with perhaps a slight shift to north/northwest on Sunday. As a result, we are likely going to see the smoke stick around through the weekend, though perhaps with some minor improvement over time (low confidence).

The good news is that winds will shift to west/southwest as a trough of low pressure moves into the Pacific Northwest on Monday. This should help to scour out the smoke by early Monday with improving air quality and visibility.

Also, don't forget that you can use our Maps overlay to track smoke and air quality:

Air Quality

• Use this map to view the current PM 2.5 air quality index. Shown as the 10-minute average for the past 24 hours and available worldwide.
• Tap here to view the map.

Smoke (surface)

• Use this map to track smoke for the next 2 days near the ground where it can impact breathing. Updated every hour and currently only available for North America.
• Tap here to view the map.

Smoke (sky)

• Use this map to track smoke for the next 2 days in the sky where it can impact visibility. Updated every hour and currently only available for North America.
• Tap here to view the map.

Air Quality Forecast

• Use this map to view the likely location of smoke and other pollutants for the next 5 days. Updated 4 times per day and available worldwide.
• Tap here to view the map.

Weekend Weather Outlook:

A more stable airmass has taken hold across our area behind Thursday's cold front, which in reality only cooled things off slightly around Jackson Hole with a more substantial cool-down east of the Continental Divide. 

As a result of the more stable air, we will stay dry through the end of the day on Friday. 

On Saturday, the atmosphere will become more unstable with some cumulus cloud build-ups, but only a slight chance of isolated thunderstorms is expected around the Tetons and Jackson Hole. The weak north/northeast flow will favor areas east of Jackson such as the Gros Ventre, Absaroka, and Wind River Ranges for a better chance of isolated thunderstorms.

On Sunday, a weak north/northwest flow along with a subtle uptick in moisture will result in a better chance of isolated thunderstorms over the Tetons, mainly across the core of the range and western slopes of the range. Any storms that develop will likely not survive eastward into the Jackson Hole Valley, however.

Despite the smoke, temperatures will be very pleasant through the weekend with highs in the low 70s in the valleys and mid/upper 50s at 9,000 feet. Overnight lows will get close to freezing in the valleys, but will remain well above freezing in the mountains.

The average high in Jackson at this time of year is in the mid 60s, so we are running a little above average. In fact, May is almost certainly going to break our 6-month streak of below-average temperatures.

Next week's outlook includes better rain/thunderstorm chances along with a return to clean air as smoke retreats back into Canada.

On Monday, a trough of low pressure will move into the Pacific Northwest with winds shifting to west/southwest across Wyoming. Most of the energy with this feature will be located to our north, but we could still see just enough energy to result in a slight uptick in shower/thunderstorm potential compared to the weekend.

As we head into the middle part of the week, a trough of low pressure will become established as the dominant pattern over California and the West Coast while a ridge of high pressure remains in place near/east of the Continental Divide.

We will see a shift to southwest winds with a series of shortwave disturbances projected to move into our area during roughly the Tuesday (May 23) to Friday (May 26) timeframe, resulting in a better chance of showers and thunderstorms capable of producing wetting rains. Wind shear (change in wind with altitude) is also expected to increase, which would result in more organized clusters of showers/thunderstorms. 

Despite the more unsettled pattern, temperatures are only expected to cool off slightly with snow levels remaining very high. Highs are projected to be in the 60s in the valleys mid to late next week.

Looking further out, the pattern looks fairly similar heading into Memorial Day weekend with near-daily shower/thunderstorm chances while temperatures should remain near to slightly above average with a mild airmass in place. 

Thanks so much for reading! Next update on Monday (May 22).

ALAN SMITH