textproduct: Cheyenne

KEY MESSAGES

- Monsoonal moisture has returned to the area, increasing storm chances through the weekend and bringing temperatures down to near or below seasonal averages.

- Numerous to widespread showers and thunderstorms are expected Thursday with isolated strong to severe storms and flash flooding possible.

- A warming trend early next week may bring us back to near normal late summer warmth.

SHORT TERM /THROUGH FRIDAY NIGHT/

Issued at 315 AM MDT Thu Aug 13 2026

Forecast for today is a bit more tricky than yesterday as we try to navigate the pitfalls of thunderstorm potential for the day. There is plentiful moisture across the region as evidenced by the low cloud ceilings, and areas in the Nebraska Panhandle already seeing lowered visibility from mist or patchy fog. PWAT values are expected to reach their maximum, at around 150-170% of normal. This should roughly equate to around 1.25-1.5 inches east of the Laramie Range. But the main issue will be our ability to produce stronger showers and thunderstorms today. Sounding profiles for our southern zones from Laramie County and the southern portions of Platte and Goshen Counties through the southern Nebraska Panhandle show a modest environment including areas of MUCAPE in the neighborhood of 700-1500 J/kg and lapse rates that could get as high as 8 C/km, but convective inhibition may put a damper on this potential. All of this not to mention daytime heating will be stifled by the widespread cloud cover from the abundant moisture means storms will need to work to be strong enough to cause issues. But if stronger storms can occur, we could see rainfall rates in excess of 1-2 inches per hour, or the potential for training activity dropping several rounds of rainfall over the same location(s), alongside a meager severe risk for the aforementioned region. A marginal severe risk for hail and/or strong winds is expected for the aforementioned area, and we have collaborated with our neighbors in Boulder to issue a Flood Watch to include Laramie County and the southern Nebraska Panhandle up through both Scottsbluff and Alliance. While the strongest storms may stay just south of Alliance, thinking was that the eastern half of this area saw fairly decent rainfall yesterday including Alliance itself at just under 1.5 inches, and so if we can get further notable precipitation here then a flood risk will be possible. Otherwise today the widespread cloud cover will keep us the coolest we've been in a while, with highs only reaching the 70's for most of our area.

Moving into Friday PWAT values will descend just a bit, but we'll still be looking at 130-150% of normal. Clearing clouds during the morning into the afternoon may also promote a bit better daytime heating and thereby fueling instability and lapse rates (1000-2000 J/kg and 8-9 C/km respectively). This has helped to expand the severe risk into our area, with another marginal risk for hail and/or winds for Laramie County and into the southern Nebraska Panhandle. This area will also be at the most notable risk for excessive rainfall. CAMs get another round of activity going as we heat up during the early afternoon with a decent line or two of fresh storms off the high terrain and multiple rounds of activity possible through the afternoon and into the evening. Once again just like the previous couple of days though, outflow debris and ongoing activity will likely begin to stabilize the atmosphere and limit our strongest potential to earlier on. But the increased heating will warm us back up, with temperatures 6-12 degrees warmer than Thursday.

LONG TERM /SATURDAY THROUGH WEDNESDAY/

Issued at 245 PM MDT Wed Aug 12 2026

As the long term period progresses, the ridge starts flattening out as a low approaches from the PNW. Shortwaves move northward toward our region which brings widespread chances for showers and thunderstorms to our area. This moisture is still coming into the area as monsoonal moisture. Precipitable water values stay around the 90th percentile range, slowly tapering off through this long term period. With this plentiful moisture, there is higher confidence in precipitation each day through this period. Precipitation chances are greatest in the afternoon to evening hours through the CWA. 700mb temperatures are around 10-15C bringing us seasonal daytime highs and overnight lows.

AVIATION /06Z TAFS THROUGH 06Z FRIDAY/

Issued at 1125 PM MDT Wed Aug 12 2026

Difficult TAF forecast with timing and pinpointing when or if a terminal will get impacted by showers and/or thunderstorms. If a storm comes near or goes over a terminal, expect gusty and erratic winds. With the added moisture from Wednesday's storms, decrease in VIS is possible in BR and/or FG at KCYS, KBFF, KCDR, KSNY, and KAIA. This will be possible through most of the night and end by sunrise. Additional storms are likely Thursday, bringing increased chances of thunderstorms. Since the convective nature, kept PROB30s out of the TAFs and used VCTS due to low confidence.

CYS WATCHES/WARNINGS/ADVISORIES

WY...Flood Watch from 3 PM MDT this afternoon through this evening for WYZ117>119. NE...Flood Watch from 3 PM MDT this afternoon through this evening for NEZ003-019>021-054-055.