textproduct: Cheyenne

KEY MESSAGES

- A slight chance of rain is possible for the southern Nebraska panhandle into Wednesday evening.

- Cooler temperatures continue through Thursday, but warmer and drier weather will prevail Friday through early next week.

SHORT TERM /THROUGH FRIDAY NIGHT/

Issued at 151 PM MDT Wed Sep 30 2026

Tonight...The WSR-88D radar reflectivity from our radar and from Denver, shows very light bands of rain showers over Morrill and Cheyenne Counties of the southern Nebraska Panhandle, with this precipitation so light that much of it is evaporating as it falls due to the advection of drier air at low levels as seen on the theta- e advection pattern. Still though, radar reflectivity does show the northern extent of the rain shield moving slowly northward to Sterling, Colorado and some of these showers may skirt our Cheyenne County of the southern Nebraska Panhandle.

Otherwise, the upper trough aloft moves from northeast New Mexico to the Oklahoma Panhandle by dawn, with cooler air at low levels advecting into our counties. Quiescent weather anticipated overnight.

Thursday...As the trough aloft opens up and propagates over eastern Kansas, northwest flow aloft develops over our counties. Atmospheric moisture looks too scant combined with any lifting mechanisms to produce any precipitation. 700 mb temperatures near 6 Celsius will yield maximum temperatures in the lower 60s to lower 70s, with the coolest readings across the northern Nebraska Panhandle in the cooler low level airmass behind the dry cold front.

Thursday night/Friday...Northwest flow aloft continues with a surface trough developing across southeast Wyoming and a strengthening low level jet forming over the Nebraska Panhandle, with boundary layer progs suggesting a stratus field and some possible fog developing across the Nebraska Panhandle, though confidence in fog development is not sufficient at this time to include it in the gridded forecasts.

For Friday, the warming trend continues under northwest flow aloft, with 700 mb temperatures near 10 Celsius yielding maximum temperatures from the lower 70s to lower 80s. A surface trough will develop over southeast Wyoming with a decent low level convergence axis, however, low and mid level moisture will be too scant for any showers or thunderstorms.

Friday night...Under northwest flow aloft, surface troughing develops over southeast Wyoming and local mixing effects will produce a relatively mild night for early October, especially in Platte County and Wheatland due to downslope katabatic warming.

LONG TERM /SATURDAY THROUGH WEDNESDAY/

Issued at 151 PM MDT Wed Sep 30 2026

Global ensemble forecast guidance remains generally unchanged compared to yesterday regarding the long-term forecast period from this weekend into next week. High confidence exists for tranquil weather through much of the long-term period. Large-scale ridging will dominate the weather pattern over the western CONUS resulting in generally mild above-average temperatures and limited precipitation chances over southeast Wyoming and western Nebraska. This ridging pattern continues to be a result of the highly active tropical pattern over the eastern Pacific. Numerous EPAC and CPAC tropical storms will continue to move west and then recurve to the north in the mid-latitudes of the central Pacific, resulting in potent synoptic troughing over the Bearing Sea/Gulf of Alaska. This setup then drives downstream ridging over western North America, which is apparent once again in today's ensemble mean guidance. As mentioned yesterday, these types of stable-synoptic-wave patterns can often persist for weeks or more, locking in high-confidence forecasts over much of the west including our region.

Local details remain largely unchanged in the forecast. Above- average temps are expected each day from Saturday onward. High confidence exists in temps around 5 degrees above average this weekend (low to mid-70s east of the mountains) and highs 10 to 15 degrees above average through next week. The one new exception in the forecast in today's guidance is a very weak wave in the overall ridge which may move through on Tuesday. Ensemble guidance has a very high amount of spatiotemporal dispersion with regard to this system. Some members do not even show this wave, and others bring it through strong enough to produce some weak showers over the higher terrain of southern Wyoming and northern Colorado. We will opt for the driest solutions for now given recent model performance with similar systems. Mild temps even during the overnight hours should continue to hold off the first frosts for any populated areas outside of the mountains. Afternoon RH values will drop to near or slightly below 20% throughout the weekend during the afternoon hours across all of southeast Wyoming and portions of the Nebraska panhandle. However, generally light surface flow out of the west less than 20 mph will likely preclude the need for any fire weather headlines. The synoptic pattern described in both today's and yesterdays discussion will continue to result in high forecast confidence throughout the entire long-term period with limited societal impacts expected.

AVIATION /06Z TAFS THROUGH 06Z FRIDAY/

Issued at 1122 PM MDT Wed Sep 30 2026

High level clouds continue to move through portions of the CWA as a robust storm tracks across the Central Plains. Chances of precipitation remains nil as the bulk of the shower activity will stay to our south and east. So, expect VFR conditions to prevail across all terminals for the duration of this TAF period. No other aviation weather concerns for this forecast period as winds overnight into Thursday will be generally less than 15 knots.

CYS WATCHES/WARNINGS/ADVISORIES

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