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 150 AM MDT Fri Sep 25 2026

Current observations across the region show that the low clouds and fog are slow to develop over the eastern plains at 100 AM with several sites reported SCT to occasionally BKN cloud cover at 3000 feet. Short range models and ensembles have caught onto this trend and are now showing low clouds and fog developing closer to sunrise across much of the area along with a more patchy coverage of fog. Models show hardly any fog developing north of the North Platte River valley, so may need to remove that from the forecast. For now, lowered most of the coverage to patchy and ended it around 800 to 1000 AM. Upslope winds have been slow to develop ahead of the subtropical upper level disturbance. Otherwise, kept widely scattered showers and a some rumbles of thunder along the I-80 corridor early this morning with KCYS and KFTG radar loop showing returns increasing across the mountains in northern Colorado.

For Friday, models continue to show a more organized band of showers and thunderstorms developing near the mountains around noon and progressing eastward across the eastern plains through the afternoon and evening hours. This activity looks to be colocated with the upper level trough/disturbance axis ejecting northeast across the area. Tricky coverage and intensity forecast for today with models showing a good chance at some locally higher QPF amounts. However, model soundings show some lingering CIN east of the Laramie Range and especially over western Nebraska this afternoon and evening which may limited thunderstorm activity and heavy rainfall. Kept POP peaking at around 300 to 500 PM (around 50 percent) and gradually tapered them down to 30 percent by this evening from west to east. Not the best lapse rates on area soundings, but there is certainly long/skinny CAPE profiles, which suggest locally heavy rainfall. With ample cloud cover today, lowered high temperatures a few degrees with afternoon into the mid 60s to the low 70s.

Mid to upper level flow veers into the west on Saturday allowing drier air to finally push into the region as dewpoints lower into the mid 30s to mid 40s. Little to no forcing present with low CAPE, so kept POP below 10 percent even though some high res CAMS show some activity trying to develop over Carbon and Albany counties late in the afternoon. Pleasant day expected with highs climbing into the mid 70s to mid 80s, warmest below elevations of 5000 feet. Unseasonably mild Saturday night with lows mostly in the 50s across the eastern plains.

LONG TERM /SUNDAY THROUGH THURSDAY/

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 /12Z TAFS THROUGH 12Z SATURDAY/

Issued at 600 AM MDT Fri Sep 25 2026

A subtropical upper level disturbance is forecast to lift north and then northeast across the region today. Morning low clouds and fog will lift ahead of a line of showers and thunderstorms that will quickly move across the eastern plains later this afternoon. Gusty winds and brief heavy rainfall possible into this evening.

HAZARDS/WEATHER TRENDS: Tricky low confidence LIFR forecast this morning with low clouds and fog around the area. However, fog and IFR conditions have been brief and intermittent at times prior to 12z with little sign of persistence, likely due to the light and variable wind speeds. Kept forecast as is for KCYS, KSNY, KAIA, and KBFF since confidence isn't high enough to improve the overall conditions quite yet. Confident enough to remove any mention of IFR from KLAR and KCDR though, with fog likely not making it into those locations. Otherwise, conditions will be slow to improve over KAIA and KSNY with IFR conditions possible past 18z. Higher confidence that a line of showers and thunderstorms will impact KLAR, KCYS, and possibly KBFF and KSNY this afternoon through this evening. MVFR VIS and CIGS possible with this activity along with gusty winds and brief heavy rainfall.

CYS WATCHES/WARNINGS/ADVISORIES

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