textproduct: Western and Central Wyoming

KEY MESSAGES

- Showers continue today through Wednesday, with the most numerous showers shifting further east, especially on Wednesday.

- Snow is expected in the higher elevations of the mountains, especially above 9000 feet. The highest amounts will be in the Wind River Range, where there is a greater than 1 out of 2 chance of 2 inches or more.

- Drier weather moves into northwestern areas on Wednesday, spreading everywhere by Thursday night. Dry and mild weather is expected Friday into the weekend.

DISCUSSION

Issued at 153 AM MDT Tue Oct 13 2026

What I have noticed this year is that when we get a certain kind of weather, is that it sticks around for a while, with a few exceptions of course. Examples include the several heat waves we had this year, the monsoon over the summer that seemed to drag on forever and the period in the latter part of June when we seemed to have a severe thunderstorm somewhere in the area. The past few weeks have been an example, we had a prolonged period of wet weather in the middle of September. We then had a strong ridge across the area for better part of three weeks, bringing dry and warm weather for most of the latter part of September as well as the first several days of October. We are now in the period of the everlasting moisture, courtesy of what was left of Tropical Storm Rachel and now a slow moving bowling ball, AKA and upper level low, now dropping southward over Nevada. And this system will influence our weather for a couple more days.

For the third night in a row, we continue to have areas of showers moving across the area. Satellite imagery shows cloud tops are slowly warming, so coverage and intensity of showers should gradually decrease through the rest of the night, although some will linger through the night. As for today, it will be fairly similar to yesterday with another day of below normal temperatures and plenty of cloud cover. There will also be showers around through the day. However, with the low moving further way, coverage should be less than previous days. This is also the first day of the past few there is not an excessive rainfall outlook, so amounts should be less.

Steadier precipitation may increase tonight though, especially across southern and central Wyoming as the upper level low begins to make a turn to the east and moves across Colorado. This will turn flow to the east and bring some upslope flow into the area. The area looks to be on the northern edge of the deeper moisture though, so rainfall amounts do not look excessive at night. The most favored areas will be across the Wind River Basin to Casper with the upslope flow. I will discuss amounts later in the discussion. And this includes potential snowfall amounts in the mountains. Precipitation will continue into Wednesday, but there is some uncertainty here. There are some differences in guidance in regards to the movement of the upper level low. The bottom line is, the further north it moves, the further to precipitation can wrap back into the area. The greatest confidence for rain will be from Natrona County southwest to Rock Springs and on to the south and east. Chances drop further north and west, with the northwestern part of Wyoming largely dry on this day. And this continues through Wednesday night as well as the low continues to move eastward.

There is one more concern for Wednesday night. As the upper level low moves eastward, lee cyclogenesis will occur over Colorado. This will tighten the pressure gradient across the area, increasing wind. Much of the area East of the Divide as well as southern Wyoming have a greater than 1 out of 2 chance of wind gusts past 30 mph from later Wednesday night through Thursday. The strongest gust would be in the wind prone areas in Johnson County, where there is a 1 in 3 chance of gusts past 50 mph. Low level winds do not look sufficient for high wind though. Following this, all rain ends on Thursday and then ridging builds back over the area, bringing a return to dry conditions and near to somewhat above normal temperatures.

PRECIPITATION AND SNOW AMOUNTS...We still start with precipitation. Reasoning remains similar to yesterday with the highest amounts in the mountain ranges and across central and southern Wyoming. Most of the mountains, except for the far north, as well as much of the Wind River Basin and Natrona County, have at least a 3 out of 5 chance of a quarter of an inch of precipitation or greater through Wednesday night. The 1 out of 2 chance of three quarters of an inch or greater runs roughly from east of Riverton to Casper and southward to the Continental Divide. The smallest amounts would be across northern Wyoming as the low digs to the south.

Now on to snowfall. Snow levels look to bottom out Tuesday night into Wednesday, with 700 millibar temperatures falling to around 7000 to 7500 feet. Most of the mountain ranges have at least a 1 in 2 chance of an inch of snow from Tuesday morning through Wednesday night. However, for advisory level amounts, which is 6 inches or greater, the only location is the Wind River Range. Most areas above 9000 feet continue to have at least a 1 in 2 chance of 6 inches of snow or more. The highest peaks will likely (a greater than 2 out of 3 chance) see over a foot of additional snow, but impacts here are few to none. So, we will keep the advisory going for now. The heaviest snow should end by sunrise Wednesday as the deeper moisture moves to the east of the mountain range. As for the lower elevations, a few flakes can't be ruled out, but no accumulation is expected.

AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/

Issued at 438 AM MDT Tue Oct 13 2026

The aviation forecast is difficult and somewhat uncertain on details. Showers should remain isolated through the morning before increasing again later today and especially tonight as steadier rain moves back into some locations, especially in vicinity of KCPR, KLND and KRIW. All stations will have periods of MVFR and IFR at times, with LIFR possible for brief periods in heavier showers. Patchy fog may also bring brief IFR to LIFR conditions, especially in vicinity of KRIW, KLND and KCPR. Specific timing of areas of showers remains uncertain. Conditions should improve across the western sites after 06Z tonight, especially in vicinity of KJAC as deeper moisture begins to move away to the east. Mountain obscurations will remain frequent through the TAF period. Wind should generally be light, generally 11 knots or less through the TAF period.

RIW WATCHES/WARNINGS/ADVISORIES

Winter Weather Advisory until 6 AM MDT Wednesday for WYZ014- 015.