textproduct: Western and Central Wyoming

KEY MESSAGES

- Showers have ended across the area this morning, with areas of fog possible. Dry conditions with mostly clear skies will be in place by midday. Wind gusts up to 30 mph will develop from South Pass to Casper through the afternoon.

- Mainly dry and tranquil weather is expected on Thursday, with all but far western Wyoming remaining dry through Friday. Temperatures will average 8 to 12 degrees above normal on Friday from Rock Springs to Casper and Buffalo.

- A weather system may bring more substantial rain and mountain snow Sunday into Monday, but details in placement and amounts of the heaviest rain and snow remain rather uncertain.

DISCUSSION

Issued at 303 AM MDT Wed Oct 28 2026

The forecast is again working out fairly well this morning as some jet enhanced precipitation is currently working its way across roughly the southern half of the area, including here at the humble Riverton Weather Abode. It is rain at our office right now, but there has been some snow in places like Pinedale and Big Piney. A few lightning strikes have also been noted. Almost all showers should end by sunrise today. However, there will likely be some slick spots on roads that saw snow. And, a few locations have seen the fog monster crawl out of this lair to feed on the moisture from the precipitation.

Once the showers end, ridging should build across the area and bring at least two days of fairly tranquil weather with many areas having three days of fairly quiet weather, lasting through Friday. There will still be somewhat of a pressure gradient in the wind prone areas from Muddy Gap through Casper so a gusty wind will continue there, but not nearly as strong as yesterday. Wind should decrease through Friday as well. Temperatures will also be on the rise. The temperatures in the forecast today are probably the coolest it will be. I could see it 3 to 5 degrees higher on each day. The warmest day looks to be Friday when places like Casper may be well up into the 60s.

The next chance of showers will begin to move into western Wyoming as a trough rotates around an upper level low off of the Pacific Northwest Coast and brings increasing moisture to the area. There continues to be disagreement in the guidance in regards to placement and intensity of the showers, with some models, like the GFS, keeping things mainly dry through most of Saturday. For now, most areas have some chance on Saturday but most places should be dry most of the time.

The most interesting feature of the forecast though is from Sunday into Monday. There is an interesting and complex situation setting up. We have two main players. The first is the aforementioned upper level low that will get kicked eastward into the Rockies Sunday night and into Monday. Another player is an area of low pressure from further south in the Pacific Ocean that will move into southern California on Sunday and track east to northeastward into the Southern Rockies. The big question is how will these systems interact, how much moisture from the much wetter southern system can get drawn northward and if the systems phase and where will they phase. The guidance of both the deterministic and ensemble varieties, continues to have a rather wide spread in regards to all of these variables. In the deterministic realm, the ECMWF phases the systems further eastward and is slower, which would mean a wetter solution. The GFS is faster and drier, with the phasing and deepening of the low further east. So, although we are fairly confident of at least some unsettled weather across the area, precipitation amounts and the placement and timing of precipitation remains highly uncertain. A first look at the NBM ensemble gives at least a 1 in 2 chance for most areas to get at least a quarter of an inch or QPF from Sunday morning through Monday evening. As for snow, the 1 in 2 chance of 6 inches over the same time frame is largely confined to the mountains above 8000 feet. It could get cold enough for lower elevations to see the first snowflakes of the year, but chances of decent accumulations of greater than 2 inches remains low, under 1 out of 4 at this time. But remember, this is still 5 days out so a lot can and probably will change. Stay tuned as we get closer to the event for more clarity. After this system departs, there is good model agreement in ridging building over the area, possibly bringing dry and tranquil conditions for much of next week.

AVIATION /18Z TAFS THROUGH 18Z THURSDAY/

Issued at 1112 AM MDT Wed Oct 28 2026

IFR flight conditions from freezing fog at KPNA and KBPI is expected to gradually lift through 19Z. Once the fog lifts, there is high confidence in dry and VFR flight conditions through at least 18Z Thursday. Winds are expected to remain light at most terminals the entire TAF period. The exception is KCPR where westerly gusts around 25kts are forecast through sunset this evening.

Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for the latest information on icing and turbulence forecasts.

RIW WATCHES/WARNINGS/ADVISORIES

None.