951 FXUS65 KCYS 051730 AFDCYSArea Forecast Discussion National Weather Service Cheyenne WY 1130 AM MDT Fri Sep 5 2025
.KEY MESSAGES...
- Below average temperatures with lingering smoke possible on Friday.
- A warming trend will develop for the Saturday through Thursday period, with chances for isolated to scattered late day showers and thunderstorms each day.
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.SHORT TERM /THROUGH SATURDAY/... Issued at 238 AM MDT Fri Sep 5 2025
A cold front that moved through earlier has left lingering light showers across southeast Wyoming and western Nebraska. These showers will continue through the early morning hours per Hi-Res guidance, but will not pose much of an impact besides getting the ground wet. The deep trough responsible for the cold front will sit over the north-central part of the country through Friday, leading to cool, below average temperatures for the beginning of September. With 700 mb temperatures in the lower single digits, highs today will only be in the 60s to low 70s, which is about 10 to 12 degrees below average. For the most part, the cooler weather and trough will keep precipitation chances pretty minimal today, however, cannot rule out a few high terrain showers developing during the afternoon. Besides the cooler and drier weather, the cold front was temporarily able to clear out some of the near surface smoke from Canadian wildfires. Unfortunately, near surface smoke is likely to re-enter areas west of the Laramie Range during the afternoon. Once clouds clear out, most of the CWA will still see hazy skies on Friday from smoke aloft. Expect quiet conditions heading into Friday night.
Most of the CWA will wake up to a chilly, fall like morning on Saturday with lows in the upper 30s to low 40s. A few isolated areas in the northern Nebraska panhandle and Converse and Niobrara Counties could develop patchy frost given calm, clear conditions overnight combined with lows in the upper 30s. Any frost that develops will likely be brief as temperatures will quickly warm up as mostly sunny skies dominate most of the CWA. The upper-level trough that was over the north-central part of the country will push eastward into the Great Lakes Region, opening the door for weak ridging to develop over the Great Basin. This will allow 700 mb temperatures to begin to warm up into the double digits, bringing highs into the 70s. A weak shortwave will also begin to move into western Wyoming and Colorado, potentially leading to a slight chance in scattered showers and storms developing in the afternoon for areas west of the Laramie Range.
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.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... Issued at 200 PM MDT Thu Sep 4 2025
Saturday...Northwest flow aloft continues with a slow warming trend as 700 mb temperatures rise to near 8 Celsius. Looks like enough residual moisture over the far southern Snowy Range and far southern Laramie Valley for isolated afternoon showers and thunderstorms.
Sunday...As ridging aloft develops over our counties, return southeast low level flow develops, advecting low and mid level moisture across our counties, and producing scattered afternoon and evening showers and thunderstorms, mainly west of I-25. The warming trend continues with 700 mb temperatures near 10 Celsius.
Monday...The warming trend continues with low amplitude ridging aloft and 700 mb temperatures rising to near 14 Celsius. Adequate low and mid level moisture for isolated late day showers and thunderstorms mainly west of I-25.
Tuesday...As the ridge aloft transitions over the Central Plains states and our flow aloft turns southwest, temperatures will remain about the same. Enough low and mid level moisture for isolated to widely scattered late day showers and thunderstorms, mainly west of I-25.
Wednesday...Southwest flow aloft strengthens, and with warm temperatures aloft providing convective inhibition, only isolated to widely scattered late day showers and thunderstorms will be possible, mainly west of I-25. High temperatures about the same as on Tuesday.
Thursday...South southwest flow aloft prevails, and with adequate low and mid level moisture, we expect to see isolated to widely scattered late day showers and thunderstorms. Perhaps slightly cooler compared to Wednesday due to more clouds and precipitation.
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.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/... Issued at 1125 AM MDT Fri Sep 5 2025
Low to mid-level clouds continue to linger at the start of this TAF period, affecting those terminals located across southeast Wyoming and southern portions of the Nebraska panhandle. This deck of clouds should lift and clear out by mid to late afternoon, resulting in minimal aviation concerns at the surface into the evening hours. However, RWL may experience reduced VIS at times as smoke drifts into the area through at least Saturday. Elsewhere, the remaining terminals, there is the possibility of smoke that remains aloft that could affect aviation operations.
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.CYS WATCHES/WARNINGS/ADVISORIES... WY...Air Quality Alert until 1 PM MDT Sunday for WYZ104-109-111>113. NE...None.
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SHORT TERM...SF LONG TERM...RUBIN AVIATION...RZ
NWS CYS Office Area Forecast Discussion