626 FXUS65 KCYS 061722 AFDCYSArea Forecast Discussion National Weather Service Cheyenne WY 1122 AM MDT Sat Sep 6 2025
.KEY MESSAGES...
- Patchy frost possible across the area Saturday morning. Areas of smoke and haze will persist through Saturday.
- Warmer temperatures will develop for the Sunday through Friday period, with chances for isolated to scattered late day showers and thunderstorms nearly every day.
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.SHORT TERM /THROUGH SUNDAY/... Issued at 233 AM MDT Sat Sep 6 2025
Current temperatures early this morning are a bit cooler than what models have been suggesting over the last few days. As a result, used a blend of NBM 25th and 10th percentiles to bring morning lows down as effective radiational cooling takes place. Given the calm conditions, patchy frost will likely develop across much of the Nebraska panhandle as lows fall into the 30s. A few lower elevation spots and valley locations in southeast Wyoming may also see some patchy frost Saturday morning. Frost should dissipate rather quickly as temperatures warm up fast with an upper-level ridge building over western Wyoming.
With a an upper-level ridge beginning to build over western CONUS, 700 mb temperatures will rise back into the double digits for most of the CWA. This will lead to high temperatures about 5 to 10 degrees warmer than Friday with highs mainly in the 70s for most cities. With northwest flow expected to continue aloft, Canadian wildfire smoke will persist through the day Saturday, leading to hazy skies. Near surface smoke may also persist for areas west of the Laramie Range where light winds will keep air a bit stagnant. For the most part, the upper-level ridge will limit precipitation chances, however, a weak disturbance moving through the ridge could spark a few high terrain storms during the afternoon and evening hours. As the disturbance moves across Wyoming, light showers could linger into Saturday night.
By Sunday, the upper-level disturbance will be over the CWA. This will provide lift as well as a little mid-level moisture needed for storms to develop. Coverage of storms will be more widespread compared to Saturday, with storms developing in Wyoming by early afternoon and eventually spreading east into Nebraska by late afternoon. There is a bit of instability present, so thunderstorms are likely with a few potentially containing small hail and gusty winds. Storms will continue into the evening hours.
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.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... Issued at 202 PM MDT Fri Sep 5 2025
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 13 Celsius.
Monday...The warming trend continues with low amplitude ridging aloft and 700 mb temperatures rising to near 13 Celsius. With drying at the low and mid levels, no precipitation is expected.
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.
Friday...As the shortwave trough aloft pivots into western Colorado, the flow over our counties will turn southerly, advecting more low and mid level moisture and clouds into our counties, and producing a chance of late day showers and thunderstorms. With more cloud cover, temperatures will be a bit cooler compared to Thursday.
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.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/... Issued at 1122 AM MDT Sat Sep 6 2025
VFR conditions will prevail for a majority of this TAF period across all terminals in our CWA along with generally light winds. However, smoke from Canadian wildfires may drift into our CWA once again, leading to hazy skies, with surface smoke potentially reducing VIS slightly at times, with the greatest chances for our western terminals. A few widely scattered storms may develop later this afternoon and move into the vicinity of southeast Wyoming terminals.
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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