Ralston, WY 82440 Weather

Key messages

- A pleasant day today, with increasing high clouds and highs in the 50s to low 60s. A similar day is in store on Friday.

- Shower chances (20% to 40%) increase across western and southern Wyoming Friday night into Saturday. However, shower activity will be more scattered so most will remain dry during this time.

- A weather system will bring showers to most of the area Sunday into Monday, with moderate snow likely ( greater than 60% chance) in the mountains. Exact timing and placement of the heaviest precipitation remains somewhat uncertain.

Discussion

Issued at 205 AM MDT Thu Oct 29 2026

Early this morning, I am listening to old school rhythm and blues. When I turned to the station, it was a rather convenient coincidence that the first song I listened to describes the weather across much of the area today. Shortwave ridging will build across the area today, and bring a dry day with above normal temperatures for late October. Some mid to high level clouds will move in at times, but nothing other than that. If you are still wondering about what the song that describes the weather today, it is "Lovely Day" by the late, great Bill Withers. So if you can, get out an enjoy it. Dry weather will continue through tonight, but more clouds may keep temperatures a bit warmer than Wednesday night.

The pattern begins getting more active following today. Clouds will increase Friday as moisture deepens ahead of a shortwave moving in from the southwest. Guidance continues to trend slower with the wave though. Most of the area will have a dry Friday with another day of above normal temperatures. Some locations, like Casper, will be well up into the 60s. As for precipitation, we can't rule out a shower in southwestern Wyoming. However, the chance is less than 1 out of 6 and most showers would not occur until after sunset Friday night.

Guidance has also trended somewhat drier for Saturday. The main showers will be across western and southern Wyoming again, with diminishing chances further north and east. But even in the west, amounts look rather light, generally a tenth of an inch or less. Although the forecast East of the Divide is dry right now, we can't rule out a shower in some locations. Chances are rather low at this time though, generally less than 1 out of 7, and most locations East of the Divide would likely remain dry through at least Saturday evening. As for the trick or treating weather, most guidance shows mainly dry conditions for most of the area Saturday evening with at most a 1 in 4 chance and that would be in the far west. It will be another fairly mild day as well. So, things look good for all the kiddos to get their annual sugar rush from the various forms of candy (save a Snickers bar for me).

All eyes are still looking at what will happen Sunday into Monday. We continue to have a complex set up, and details still remain somewhat uncertain at this time. There is a bit more agreement at this time though with the general pattern. The two main players are an upper level low that will drop southward along the Pacific Northwest Coast and move onshore in northern California Saturday night and another, much wetter low that will move onshore in southern California on Sunday. It looks like these two systems will phase to the south of Wyoming and continue East, with lee cyclogenesis occurring over Colorado Sunday night. The deepest moisture will remain to the south of Wyoming, over the desert southwest and over portions of Utah and Colorado. This should keep amounts down somewhat. And continuing the trend, the system is slower. All areas will have a chance of showers on Sunday, but most will be across western Wyoming. The wettest period looks to be Sunday night into Monday morning as the low moves eastward. There is a new wrinkle in a few of the models for Monday. It is that some ensemble runs, as well as the operational European model, show a good area of wrap around moisture that could impact areas East of the Divide Monday into Monday night. This is the first run showing it though, so I'm not completely buying into it yet. We will continue to watch it though to see if it persists though.

Now we move on the precipitation amounts, in the 48 hour period ending Tuesday at 6 am, the NBM ensemble guidance shows most areas having at least a 1 in 2 chance of a quarter of an inch of precipitation, with the highest chance in the mountains. Areas with a greater than 1 out of 2 chance of 0.75 inches or more are generally confined to the mountains. The greatest chance will be in the western mountains, where a period of orographic enhancing westerly flow will bring heavier amounts, as well as in the Bighorn Range, more from the possible wrap around moisture.

And the question more people are wondering about, will there be snow and how much and where? One change today is the most guidance has trended warmer, so the chance of accumulating snow in the lower elevations is looking less likely (less than a 1 out of 3 chance at this time). Snow levels look to remain fairly high through Saturday night. The 700 millibar temperatures are expected to remain near to above 0 degrees celsius, putting snow levels at 8500 feet or higher. This could still impact some mountain passes though, especially Togwotee Pass. Colder air then moves into the area as the low passes and flow turns to the north. There is still a difference on the models with snow levels past this though, with differences of up to 1500 feet. At this time, most guidance shows some snow in the western valleys, although amounts will be on the light side. As for the first guess of accumulations, there is a greater than 1 in 2 chance of 6 inches of new snow across most of the mountain ranges above 9000 feet through the event. The chance of a foot or more is largely restricted to the highest elevations though. My first guess would be that we may need some winter weather advisories for some of the mountains with the impact to passes but nothing more. As for the East of the Divide lower elevations, the best chance would be above 6500 feet on Monday as the cooler air moves in. This would include places like Dubois or possibly the south side of Casper, but accumulations would be light, an inch or less.

Following this, ridging will build back over the Rockies for much of next week. This bring a period of tranquil weather with near to somewhat above normal temperatures and dry conditions. Looking way out, the next chance of showers might be next weekend, but details are obviously impossible to nail down this far out.

Aviation

Issued at 445 AM MDT Thu Oct 29 2026

VFR conditions will continue through 12Z with high pressure over Wyoming. High clouds will move in at times, especially after 00Z but ceilings will remain above 12000 feet. Wind should remain 11 knots or below for the most part. Wind gusts between 15 and 20 knots are possible in vicinity of KCPR after 18Z today but should decrease after sunset.

Watches, warnings and advisories

None.