textproduct: Cheyenne

KEY MESSAGES

- Chances for scattered rain and snow showers will continue for portions of southeast Wyoming through this evening. Isolated thunder remains possible.

- Warmer and drier conditions are expected to return for Friday into the weekend.

SHORT TERM /THROUGH FRIDAY NIGHT/

Issued at 300 AM MDT Thu Apr 30 2026

Mostly cloudy skies are over the area this morning as a weak upper level shortwave slowly progresses through. An expansive, but relatively weak surface high pressure is filling in behind the upper level features, pushing down from the north this weekend. The frontal boundary was relatively diffuse but most of the area is now seeing weak northerly winds as surface pressure slowly rises. Upslope flow and weak frontogenesis are supporting some show shower activity mainly in Carbon and Albany counties. This is tied to the surface front slowing as it pushes up against the higher terrain. Snow showers are leading to slick spots and reduced visibility along I-80. A Special Weather Statement has been issued through 6AM, but accumulations are expected to be sub-advisory. Still, travelers may encounter slick or hazardous conditions this morning. Expect this to improve quickly once the strong April sun rises. Coverage of snow shower activity should also come down around sunrise, but then pick up again around midday with minimal convective instability expected to develop. We may also see a few rumbles of thunder with this activity. The High Plains north and east of Cheyenne will see little to no moisture from this event, and even most of Carbon, Albany, and western Laramie counties will be fairly limited. The higher peaks of the Snow Range and the northern and eastern foothills have the best chance for seeing over 0.10" of liquid precipitation through this evening.

Drier air will work in aloft overnight tonight, and bring any lingering shower activity to an end. Skies will clear from north to south, with mostly clear skies expected by daybreak Friday. Today's sloppy shortwave trough will get stuck to our south over the Four Corners states by tomorrow morning. A narrow ridge will try to sneak back into the northern Rockies, boosting temperatures once again. Expect highs on Friday to be relatively close to seasonal averages, generally mid 50s to mid 60s. Winds will remain fairly light even as humidity drops again, which should keep fire weather concerns from escalating too much.

LONG TERM /SATURDAY THROUGH WEDNESDAY/

Issued at 300 AM MDT Thu Apr 30 2026

Upper level ridging will remain in place over the area for Saturday and Sunday. 700-mb temperatures will climb to around +2 to +6C across the area for the weekend, supporting daytime high temperatures above seasonal averages. Forecast highs in the mid 60s to mid 70s each day will be about 10F above average. With winds remaining light, it should be a very pleasant weekend for outdoor activities. Saturday will remain very dry across the area with RH as low as 10%, but moisture will begin to recover on Sunday. Elevated moisture overtop a dry and deep boundary layer will return high- based virga showers to the forecast Sunday afternoon and evening, but the chance for rainfall will be fairly low.

Another subtle upper level shortwave rough moving down from the north on Sunday into Monday will be accompanied by a surface cool front. The temperature drop will be subtle, with Monday's highs expected to be just a few degrees cooler than Sunday, but surface moisture should improve significantly. Meanwhile, a sprawling upper level low will slowly move inland from the west coast on Monday, which will set the stage for an unsettled but extremely messy weather pattern beginning Monday and continuing through the middle of next week. Monday looks to be primarily convective. Synoptic forcing is muddled and weak, but we should see ample moisture in place with decent instability. Tuesday looks like a mix of convective and synoptic forcing for precipitation as a stronger shortwave aloft drops down from the north and initiates a complex interaction with the west coast closed low.

The primary uncertainty next week is how far west this northern branch shortwave will travel. Ensembles are fairly evenly split between two scenarios. The first features a stronger trough positioned further west, which should lead to 700-mb temperatures around -6 to -10C and support well-below average temperatures. The second keeps the cooler air further east, and only features a modest cool down with 700-mb temperatures dropping to between 0 and -4C. It is somewhat unclear which scenario would lead to more widespread precipitation. Each cluster contains several members with notable precipitation amounts exceeding 0.25" for much of the area. Each scenario also includes several ensemble members with little to no precipitation as well. The official forecast includes PoPs in the 40 to 70% which seems appropriate at this lead time. The precipitation outcome will depend on the interaction between the west coast closed low and the northern branch shortwave, and that will be very difficult to accurately forecast outside of a few days lead time.

AVIATION /06Z TAFS THROUGH 06Z FRIDAY/

Issued at 1050 PM MDT Wed Apr 29 2026

Northwest flow will continue tonight as an upper level trough slowly moves south out of Canada. Lowering CIGS with periods of light rain and snow possible for southeast Wyoming, with little to no precipitation over western Nebraska.

HAZARDS/WEATHER TRENDS: Expect VFR conditions to prevail with periods of light rain/snow over the southeast Wyoming terminals tonight and early Thursday. Periods of MVFR CIGS and VIS are looking a little more likely for KRWL, KLAR, and maybe KCYS between 06z and 15z. Can't rule out brief IFR conditions, especially for KLAR, but probabilities are less than 15% at this time.

CYS WATCHES/WARNINGS/ADVISORIES

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