textproduct: Cheyenne

KEY MESSAGES

- Near to record warmth expected Wednesday under high pressure aloft. Temperatures will increase into the mid-80s to mid-90s.

- Fire Weather Watches have been upgraded to Red Flag Warnings, expanded to include all of western Nebraska, and extended through Thursday evening. Critical fire conditions possible again on Friday and Saturday.

- High Wind Watches have been issued for the typical wind prone regions of southeast Wyoming from late tonight through Thursday evening.

- Next chance for precipitation returns during the weekend alongside cooler conditions.

SHORT TERM /THROUGH THURSDAY NIGHT/

Issued at 109 AM MDT Wed May 13 2026

Upper-level ridging is progged to remain in place across the CWA today with near record high temperatures expected in many areas. 700mb values are maxed out per the NAEFS Mean Temperature for this time of year, further suggesting record highs this afternoon. Mostly clear skies overnight and in the morning hours will slowly becoming mostly cloudy, especially as 700mb warm air advection leads to synoptic scale rising motion across much of southeast Wyoming and western Nebraska. Additionally, a diffuse, 700mb shortwave will propagate across the CWA today, leading to additional support for more concentrated rising motion, especially along and east of the Laramie Range. 99th percentile and above 700mb temperatures combine with southerly flow at the surface allowing for continued warming across the region. Afternoon temperatures look to max out in the low- to mid-80s west of the Laramie Range and mid-80s to mid-90s east of the Laramie Range. Unfortunately, limited moisture is anticipated this afternoon as a drier air mass moves in. With very warm temperatures and little additional moisture, afternoon minimum humidity values will drop into the 10 to 15 percent range with breezy winds developing this afternoon associated with the diffuse 700mb shortwave. These ingredients will combine to create critical fire concerns across western Nebraska where fuels remain dry and not currently in green-up. As a result, Fire Weather Watches have been upgraded to Red Flag Warnings, expanded to include the southern Nebraska Panhandle, and extended through at least Thursday night.

With the increased synoptic ascent across the region due to modest 700mb WAA and concentrated lift from the diffuse 700mb shortwave, afternoon showers are anticipated to develop, but the dry surface level will make it difficult for rain to reach the ground. In addition to this, hires model guidance suggests modest MUCAPE values across the region this afternoon, maxing out around 200 J/kg. This would be enough instability to result in a few rumbles of thunder across the CWA, especially east of the Laramie Range. Unfortunately, since precipitation will struggle to reach the ground due to the very dry surface layer, isolated, dry lightning cannot be ruled out. The best chance for dry lightning will be largely concentrated east of the Laramie Range into the western Nebraska Panhandle, where fuels are quite dry. Forecast soundings suggest Inverted-V profiles this afternoon, so gusty and erratic winds gust are likely with any shower or storm that develops this afternoon. All in all, this will only increase fire concerns as any fire that starts from dry lightning could spread easily with the gusty and erratic winds produced by the storm itself. Therefore, the southern Panhandle was added to the Red Flag Warnings, despite humidity values remaining slightly above critical levels, closer to 15 to 20 percent.

Moving into Thursday, the upper-level pattern starts to shift as an upper-level trough over southern Canada dips just far enough south to slightly impact the region. Upper-level winds will be largely southwesterly to zonal as the upper-level low moves eastward, with northwesterly flow developing late Thursday night into early Friday morning. Unfortunately, the best lift and moisture associated with this system will remain well off to our north and east, leading to yet another dry day across the region. 700mb temperatures cool slightly towards the 7 to 10C range for Thursday as the upper-level low briefly funnels cooler air into the region. Afternoon temperatures will remain warm, though significantly cooler than Wednesday. Afternoon highs will reach the upper-60s to mid-80s, with the coolest temperatures west of the Laramie Range. With the best moisture associated with the upper-level low missing the region and a very dry air mass moving in behind it, very low afternoon humidity values are anticipated to develop Thursday afternoon, likely 8 to 12 percent everywhere. Additionally, 700mb height gradients will respond to the nearby 700mb low over southern Canada, leading to a 55 to 60kt 700mb jet Thursday morning, decreasing to around 40 to 45kts by the evening hours. Surface winds are anticipated to respond due to modest downward omega values across the region leading to widespread gusts over 40mph, with high winds possible in the wind prone areas of southeast Wyoming. Given that this is a shoulder season, confidence is lower in the high winds manifesting, but a High Wind Watch has still been issued for Arlington/Elk Mountain, Bordeaux, and the I-80 Summit from early Thursday morning through the evening hours. Combined with very dry temperatures, the Red Flag Warnings were extended for western Nebraska through Thursday night, as overnight humidity recoveries look to be quite low. Additional extension may be needed into the afternoon/evening hours on Friday. With the very dry air mass in the region, mostly clear skies are expected with little to no precipitation chances across the region, further increasing fire concerns.

LONG TERM /FRIDAY THROUGH TUESDAY/

Issued at 109 AM MDT Wed May 13 2026

No major changes with this forecast update. Please see previous discussion for more details...

Friday will be largely dominated by upper-level zonal flow across much of the region. Temperatures will be quite warm Friday and Saturday as 700mb temperatures increase above about 7 to 10C each afternoon. Highs on Friday are anticipated to be in the low- 70s to mid-80s, with Saturday being slightly warmer in the mid-70s to low-90s. Afternoon minimum humidity values look to remain quite low Friday and Saturday, likely between 10 to 15% each day. Luckily, winds will be on the lighter side across western Nebraska, where fuels are ready to burn, and breezier across southeast Wyoming, where green-up has decreased fire spread potential. That being said, hot and dry conditions may still favor easier fire starts, though rapid fire spread is not anticipated at this time. Instability will start increasing Saturday afternoon with the continued, hot pattern, as well as a cold front pushing through the area. An isolated thunderstorm or two will be possible Saturday, especially across western Nebraska, as is common as we move into the Spring and Summer months.

Saturday into Sunday, an upper level trough will push its way into the Pacific Northwest and send a front through the Intermountain West. Some lobes of vorticity looks to accompany this front to aide in the synoptic lift to help produce some weak showers in the late afternoon to evening time period. By Sunday afternoon, the trough becomes more positively tilted pushing some strong warm air advection and vorticity lobes to give us some possibly strong rain showers through Sunday evening. As this upper level trough pushes through the Intermountain West Sunday night into Monday, the 700mb temperature gradient goes from a warm 8 to 10C and drops down to about -6/-5C giving us a decent chance for a rain/snow mix to possibly snow showers in the higher elevations above 7,0000ft early Monday morning and Monday night. During the day the summer sun is likely to keep all the precipitation as rain outside the mountain peaks for Southeast Wyoming. This trough is the start of an active weather pattern for the work week as we look to get the chance for precipitation almost every other day.

AVIATION /18Z TAFS THROUGH 18Z THURSDAY/

Issued at 1135 AM MDT Wed May 13 2026

Gusty winds are expected at all terminals this afternoon with the strongest winds in the Nebraska panhandle. Wind gusts of 20 to 35 kts can be expected. Dry microbursts will be possible this afternoon and evening as the surface remains very dry. Gusty and erratic winds will be possible in and around storms. Cannot rule out gusts over 50 kts in these storms. Storms could also have lightning but contain very little precipitation. Showers and storms will dissipate overnight, but winds will begin to pick up once again in southeast Wyoming. VFR conditions are expected for the TAF period.

CYS WATCHES/WARNINGS/ADVISORIES

WY...High Wind Warning from 6 AM to 6 PM MDT Thursday for WYZ106- 116. High Wind Warning from 3 AM to 6 PM MDT Thursday for WYZ110. NE...Red Flag Warning until midnight MDT Thursday night for NEZ434>437.