JACKSON, Wyo. – On Tuesday, showers and thunderstorms produced rain totals of 0.2 to 0.9 inches across Teton County, while Jackson saw a high of only 63ºF. Unsettled weather will linger through Thursday night with a return to more seasonal temperatures late this week.
Recent Weather
The first week of August was very hot with a high of 95ºF occurring in Jackson on August 3. However, the past week has been much cooler and we have also seen more frequent showers and thunderstorms along with some needed rainfall.
On Tuesday, an approaching low pressure system interacted with abundant monsoonal moisture to result in more widespread cloud cover, showers, and thunderstorms. Temperatures also ended up well below average with highs only in the low 60s in the valleys.
Rainfall totals were variable given the hit-or-miss nature of showers at this time of year, with rain gauges across the area picking up anywhere from about 0.2 to 0.9 inches.
Some of the higher totals include 0.91 inches at Grassy Lake, 0.74 inches in Alta, 0.70 inches in Star Valley Ranch, 0.62 inches in Moran, 0.58 inches at the Yellowstone South Entrance, and 0.41 inches in Wilson.
Jackson picked up 0.26 inches of rain on Tuesday, and has now received a total of 0.80 inches of rain so far in August as of Wednesday afternoon.
This is less rainfall than we had received through mid-August of the previous three years (which were all very wet Augusts), but is more than we saw in all of June (0.53 inches) and all of July (0.29 inches) of this summer.
Jackson averages 1.48 inches of rainfall during the month of August, so we are a little over halfway there right now.
Temperatures are currently running 1.5 degrees above average in Jackson through the first two weeks of August, but temperatures in recent days have been substantially cooler.
Upcoming Weather Pattern
Cool temperatures have persisted through much of the day on Wednesday with light rain showers occurring earlier in the day. However, we have seen a bit more sun as of late Wednesday afternoon and temperatures have shot up into the low 70s as a result.
The afternoon has been quiet in terms of rainfall so far, but some weak showers are trying to organize over the Tetons as of late afternoon, and it’s possible we could see some thunderstorms pop up as well.
On Thursday, a break in the pattern will occur in the morning with more abundant sunshine, and highs will reach the upper 70s by the afternoon.
However, another low pressure system will approach late in the day, resulting in a good chance of scattered showers and thunderstorms during the evening hours. While coverage will be scattered in nature, locally heavy downpours will be possible.
On Friday and Saturday, a break in the pattern will occur with dry conditions and more seasonal temperatures for mid-August as highs warm up into the low 80s.
On Sunday, a surge of monsoonal moisture will arrive from the south, and thunderstorm chances will return to the picture from Sunday through early next week as a result.
So far, this looks like a fairly substantial moisture surge that will at least put us in play for locally heavy rain and active cloud-to-ground lightning with storms, though a major cooldown like what we just had is not expected. Highs are projected to reach the low 80s from Sunday through early next week.
Here is a 7-day rainfall projection, representing the average of 50 simulations of the European weather model.
While rainfall is often hit or miss in these patterns that feature pop-up thunderstorms rather than organized frontal systems, this seven-day projection does paint a fairly optimistic picture for picking up some more beneficial rainfall.
Another thing you may have noticed over the past few days is the disappearance of wildfire smoke.
Winds aloft have recently shifted from a persistent westerly flow (winds blowing from the west) to a true southwest flow (winds blowing from the southwest), which is pushing most of the smoke north of our area.
Also, the fires over the Pacific Northwest (where most of our smoke had been coming from) will see some help over the next 7+ days due to below-average temperatures, higher relative humidity, and even some measurable rainfall in some areas where fires are burning.
Alan Smith, Meteorologist
