textproduct: Cheyenne

KEY MESSAGES

- Cool but seasonable temperatures will continue with a warming trend expected for the weekend.

- A brief drying trend expected for the weekend, ahead of a potential strong Pacific storm system moving into the Front Range early next week.

SHORT TERM /THROUGH SATURDAY NIGHT/

Issued at 141 PM MDT Thu Sep 24 2026

Tonight...A weak shortwave trough aloft, oriented west to east, will move slowly north across Wyoming with deeper low and mid level moisture transported northward across our forecast area. Even with a decent low and mid level theta-e ridge axis in the area, lift will be minimal due to synoptic and orographic and mesoscale features, though the usually dependable HRRR does depict isolated showers and thunderstorms developing late this afternoon, through this evening to the south of a Laramie to Scottsbluff line. Thus, will maintain isolated to widely scattered POPS for locations near the Colorado state line, and later gridded forecast updates may need to adjust POPS higher further north. Looks like fog and low clouds will become widespread as per boundary layer relative humidity and upslope wind progs, thus expect rather widespread fog to develop, which may be tempered by the areal coverage of low clouds. We did see some local areas of dense fog this morning across far eastern Laramie County of Wyoming and the southern Nebraska Panhandle, including Kimball and believe a persistence forecast for fog development is prudent due to the moist low levels.

Friday...With the flow at mid levels turning southwest, a decent surface lee trough will develop from northwest to southeast bisecting our counties from Douglas to Cheyenne, with a rather impressive 850/700 mb theta-e ridge axis along the spine of the Laramie Range and the Interstate 25 corridor. Decent low level convergence along the surface trough, combined with diurnal heating and differential heating due to terrain differences over the mountains, is expected to spawn scattered showers and some thunderstorms from the Laramie Valley northward to Douglas and also including the southern Laramie Range and central Laramie County including Cheyenne.

Saturday/Saturday night...Will see a pleasant beginning to the weekend as ridging aloft moves overhead and surface low pressure develops over central Wyoming. Although low level moisture will be adequate, warm temperatures aloft from 10 to 12 Celsius will likely provide enough convective inhibition, CIN, to minimize shower and thunderstorm potential, thus will maintain our current dry forecast. Excellent late September day for outdoor weather enthusiasts and outdoor weather activities. Quiescent overnight Saturday night with minimum temperatures in the 40s west of Interstate 25, and lower 50s further east, making it quite pleasant to open up windows for fresh, cool air.

LONG TERM /SUNDAY THROUGH WEDNESDAY/

Issued at 141 PM MDT Thu Sep 24 2026

Long term starts quiet but then we'll see a good shot of fall weather to start the next work week, giving us cooler temperatures and widespread precipitation followed by a dryout and warming period into the middle of the week. Sunday morning at least starts out relatively quiet and dry as we'll see afternoon temperatures warm in the mid 70's to mid 80's for the day. But an incoming shortwave along with increasing moisture should help to usher in a few late evening and overnight showers or storms prior to the more eventful Monday and Tuesday. The work week then starts out with a surface cold front approaching the region and moving across into Tuesday, while deep upper level troughing from the Pacific moves in and across the region. This system brings a nice influx of moisture, with PWAT values approaching 170-200% of normal. Scattered showers and thunderstorms start to overspread the region into the early afternoon hours, but guaranteed moisture encompassing most of our forecast area occurs during the evening into the overnight hours through Tuesday morning. Initial activity could include thunderstorms, with favorable lapse rates and marginal instability alongside some stout bulk wind shear for our eastern zones. Therefore, a few storms could be on the stronger side, but with how much cloud cover and overspreading precipitation we are expecting, this should be few and far between as of this writing. Otherwise, widespread QPF looks both generous and fairly plentiful, with most of our CWA seeing a tenth to a quarter of an inch, with locally heavier totals in the strongest downpours. Our mountain zones should be seeing around an inch of QPF meanwhile, and overnight temperatures into Tuesday morning will be approaching freezing, meaning they may see their first snow (albeit light) of the season. Behind the cold front, temperatures on Tuesday will sit around 5-8 degrees below normal, giving us highs in the 50's and 60's. And then expect chilly mornings through the rest of the forecast period, as low temperatures bottom out in the 40's, possibly even upper 30's, particularly if we can get any overnight clearing to allow for even more cooling. We'll be looking at similarly cool temperatures into Wednesday as highs stay in the 60's, to just around 70's, with another chance of precipitation as a shortwave passes across with deep upper level troughing just to our north as we end the long term.

AVIATION /18Z TAFS THROUGH 18Z FRIDAY/

Issued at 1139 AM MDT Thu Sep 24 2026

VFR conditions expected over the next 12 hours or so. Beginning this evening, precipitation will try to lift up into the region, but should mostly be light and scattered in nature (though activity may get strong enough to produce a rare thunderstorm, but probs are too low to include in TAFs for now). Mid to low level CIGs will file in behind this activity along with winds becoming light and less than 10 knots all sites. KCYS, KBFF, KSNY, and KAIA will be most likely to see the lowest CIGs, with decks likely to cause MVFR to IFR status, and KSNY the most likely to see sustained LIFR conditions. VIS will also be impacted by mist and fog, with conditions below 3-5 miles tomorrow morning for many of these sites. Conditions should begin clearing by the end of the TAF period with CIGs lifting as well.

CYS WATCHES/WARNINGS/ADVISORIES

WY...None. NE...None.