Forecast Highlights:

• Dry and sunny conditions will continue from Monday to Wednesday.
• Rain showers can be expected on Thursday, and possibly Friday and Saturday.
• Snow levels will be high (11-12k) on Thursday when the most widespread showers are expected, before dipping to 9-10k on Friday-Saturday but with only light precipitation expected.
• High temperatures will reach the mid/upper 70s in the valley Monday to Wednesday, and 60s on Thursday and Friday.
• Winds will be relatively light for most of the week, except on Thursday when gusty southwest winds can be expected.

Forecast for Monday to Wednesday:

Beautiful weather will continue through the first half of this week as a ridge of high pressure remains in place across the Western U.S. Highs will warm up into the mid to upper 70s each day in the valley, which is above average for this time of year, while nights and mornings will be seasonally chilly with low temps dropping below freezing.

This is a nearly perfect pattern for outdoor activities, so get outside and take advantage while you can. 

Forecast for Thursday to Saturday:

The pattern will become unsettled late this week as a minor storm system moves across the Pacific Northwest and into the Northern Rockies. This system will be fairly moisture-starved, but we'll have just enough moisture and energy to work with to produce some scattered showers along with gusty southwest winds.

Thursday looks like the wettest day as more widespread showers are expected. Right now, I would expect around a quarter-inch to a half-inch of rain in the Tetons from early Thursday morning through Friday morning, and around tenth to a quarter-inch in the valley.

Thunderstorms will also be possible on Thursday afternoon as the atmosphere will be relatively unstable.

Daytime temperatures will be cooler under increased cloud cover, but it will still be a fairly mild system with snow levels ranging from 11,000-12,000 feet during the day on Thursday.

Confidence decreases in the outlook for Friday and Saturday, as the center of the low pressure system slowly works its way from Idaho into Central and Eastern Montana. This will result in a transition from a southwest flow to a northwest flow, but it's not clear how much moisture we'll have left to work with.

Additional showers will be possible on Friday and Saturday, but rainfall should be lighter and more intermittent compared to Thursday. There's also a chance we could end up staying dry with little to no rain, and just some scattered clouds. Also, northwest winds typically have a drying/downsloping effect in the JH Valley so even if the Tetons manage to see some showers, the valley will probably only see very light rain amounts. 

A cold front will arrive on Friday and this will help to lower snow levels to around 9,000-10,000 feet on Friday and Saturday. However, with limited moisture left to work with, any snow accumulations down to these elevations will likely be minor and will melt off quickly in the days to follow.

Temperature-wise, highs in the valley will reach the mid to upper 60s on Thursday and upper 50s to low 60s on Friday and Saturday.

Outlook for Sunday (10/2) to Sunday (10/9):

High pressure will rebuild over the Intermountain West on Sunday, and this will lead to a return to a dry and sunny pattern from Sunday through the early part of next week. Temperatures will also trend warmer with highs approaching 70 by early to mid next week.

During the second half of next week, we could potentially see a weak disturbance or two approach from the Pacific with showers possible at some point.

However, the disturbances will have a tendency to weaken upon encountering the high pressure ridge over the Rockies, which will limit our potential of seeing significant precipitation. Temperatures will fluctuate with any disturbances that arrive, but overall, temps are expected to be warmer than average during this period.

Thanks so much for reading! Next update on Thursday (9/29).

ALAN SMITH