textproduct: Cheyenne

KEY MESSAGES

- Red Flag Warnings have been expanded to include all of western Nebraska and extended through Friday evening.

- High Wind Warnings remain in effect for the typical wind prone regions of southeast Wyoming from through Thursday evening.

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

- Another late season snowfall event is taking shape to start the work week.

SHORT TERM /THROUGH FRIDAY NIGHT/

Issued at 117 AM MDT Thu May 14 2026

Upper-level ridging is slowly pushing off to the east this morning as an upper-level low over southern Canada starts to move closer to the region. Southwesterly flow aloft will develop through the afternoon hours before switching to westerly then northwesterly as the base of the trough slides eastward just to the north of the CWA. A very dry airmass is moving into the Intermountain West today, leading to significantly limited precipitation chances, despite broad lift associated with the base of the trough axis. Additionally, strong westerly flow at 700mb develops this morning as height gradients strengthen across the region. A 50 to 55kt jet is anticipated to develop by 9AM this morning across the Laramie Range, with modest subsidence expected along and east of the Laramie Range, as well as near the Arlington/Elk Mountain wind prone zone. With dry, downslope winds anticipated this morning, the surface will dry out even more, further prevent any precipitation development this afternoon, as well as drop afternoon humidity values into the single digits across much of the CWA. 700mb temperatures remain warm, though cooler than Wednesday, in the 7 to 10C range. These temperatures, combined with dry, warm downslope winds along and east of the Laramie Range will lead to temperatures topping out in the mid-70s to upper-80s east of the Laramie Range and upper-60s to mid-70s west. Strong surface pressure gradients are expected this afternoon as relatively low pressure in western Nebraska and relatively high pressure across western Wyoming develop. As a result, strong surface winds are expected today, but especially in the typical wind prone areas of southeast Wyoming. High Wind Warnings remain in effect for the typical wind prone areas through 6PM tonight, while other locations will gust upwards of 35 to 45mph. Combined with very dry surface conditions, critical fire conditions are expected everywhere this afternoon, but fuels are only critical in western Nebraska. So elevated conditions are anticipated across southeast Wyoming, even though fuels currently remain in greenup. Outdoor burning is not recommended anywhere and Red Flag Warnings for the Nebraska Panhandle remain in effect through Friday evening. Poor overnight humidity recoveries are expected today and Friday night, due to very dry surface conditions.

Another dry, warm, and crispy day is expected for Friday as largely zonal flow develops aloft ahead of the next incoming upper-level trough. Largely westerly flow will continue at 700mb, favoring continued, though lighter, downslope flow along and east of the Laramie Range. As a result, the surface will remain quite dry with afternoon humidity values dropping back into the single digits to low teens. Winds will continue to be breezy across the area, with increasing potential for dry lightning Friday afternoon. Temperatures Friday afternoon with max out in the mid-70s to mid-80s across the area. Combined with dry and breezy conditions, the Red Flag Warnings will remain in effect through Friday evening.

LONG TERM /SATURDAY THROUGH WEDNESDAY/

Issued at 117 AM MDT Thu May 14 2026

No major chances with the forecast update tonight. Please see previous discussion for more details...

A wet and unsettled pattern is taking shape for the the long term period for southeast Wyoming and western Nebraska. This pattern will be largely driven by an approaching trough embedded in westerly flow over the northwest CONUS. This trough will move inland on Saturday and pass through the region on Sunday, bringing lowering heights and a plume of pacific moisture aloft over the higher terrain. After a mild day on Saturday with a high likelihood (over 75% chance) of above average temperatures throughout the high plains, a the surface frontal boundary is expected to drop south through the northern high plains. This boundary will reach east-central Wyoming by daybreak on Sunday and push south throughout the day, bringing easterly upslope flow and overcast skies as well as a cooldown in temperatures. While isolated showers will be possible on Saturday afternoon and evening in a deeply mixed, prefrontal airmass, Sunday appears to bring high confidence of area-wide light to moderate rainfall, especially in the favored easterly upslope regions of the Cheyenne Ridge and Laramie Ranges. Currently, the ECMWF ensemble is a bit wetter than most NAEFS members, supporting perhaps up to an inch of rain in the south Laramie Range into the Cheyenne Ridge from Sunday through Sunday night. Confidence remains only moderate for these heavier rainfall amounts, as subtle differences in ensemble clustering suggest some of the deeper upslope moisture may sneak a bit too far south into the Colorado front range and leave eastern Wyoming slightly drier.

From Monday onward, models begin to diverge as GEFS members quickly push this system eastward transitioning us into a drier pattern, whereas ECMWF ensemble guidance generally supports a developing mid-level low over western Wyoming and continued rainfall over much of the state as well as western Nebraska on Monday. Given the post-frontal airmass in place and generally suppressed jet pattern we have been in lately, the instinct currently is to favor the slightly wetter pattern for early next week. Higher confidence exists in continued near-average temperatures, with any days of particularly heavy rainfall likely resulting in lower than average weather. As far as snow for our late-season winter enthusiasts, chances are looking increasingly likely for a snowfall refresh in the higher terrain. Most ensemble guidance keeps mid and upper-level temperatures cooler through early next week, resulting in lower snowfall levels in the Snowy Range, Sierra Madres, and even Laramie Range by Mon-Tues. Up to a foot or more of late-season snowfall is being suggested by at least 30% of ensemble guidance from the Sunday-Tuesday timeframe, especially at elevations above 10kft. We will have to see if this trend continues in guidance but confidence is certainly growing in another late- season snowpack boost.

AVIATION /06Z TAFS THROUGH 06Z FRIDAY/

Issued at 1122 PM MDT Wed May 13 2026

VFR conditions will continue across all terminals for the duration of this TAF period. Breezy conditions for a majority of the sites with gusts up to 30 knots through the overnight hours, while KCYS and KCDR will see winds taper off to generally less than 10 knots. A strong pressure gradient will tighten over the region Thursday morning, causing winds to ramp up across all terminals by 15Z with westerly gusts 25 to 45 knots. Wind shear is also expected to impact most of the Nebraska sites during the overnight and early morning hours before surface winds increase.

CYS WATCHES/WARNINGS/ADVISORIES

WY...High Wind Warning from 6 AM this morning to 6 PM MDT this evening for WYZ106-116. High Wind Warning until 6 PM MDT this evening for WYZ110. NE...Red Flag Warning until 7 PM MDT Friday for NEZ434>437.