textproduct: Cheyenne

KEY MESSAGES

- Red Flag Warning remains in effect through 9 PM Sunday for all of southeast Wyoming for very low humidities and significant gusty winds.

- Elevated to critical fire weather conditions will likely persist through Tuesday with the potential for another Red Flag to be issued for Southeast Wyoming.

- Hot temperatures continue through the start of the week before a pattern change begins to occur as precipitation chances start to rise and temperatures fall, dropping to below normal by the later half of the week.

SHORT TERM /THROUGH MONDAY NIGHT/

Issued at 259 PM MDT Sun Aug 9 2026

A stalled front will be the likely catalyst this evening as the showers push through from the West. SPC has a Marginal Risk for severe thunderstorms in the Panhandle. The Hi-res models put around 2,000 joules of CAPE east of the stalled front. DCAPE values continue to be around 1,000-2,500 joules with moisture advecting in at the mid levels and a stout dry layer at the surface for the classic inverted-v Sounding. The stalled boundary runs pretty much along the I-25 corridor. So this afternoon and evening these weak thunderstorms/gusty showers will likely produce "virga bombs" or frequent microburst like wind gusts pretty much west of I-25 and through our northern counties of Converse and Niobrara. These showers or weak thunderstorms will cross the boundary into an environment with moisture and CAPE. It will be like when you're playing those popular racing games and you hit a power up, except these showers and storms will slightly intensify but the bulk shear will limit things a little bit being between 30-40kts and the CAPE slowly increasing to around 1,000-1500 joules in the northern panhandle and 2,000-2,500 joules in the southern panhandle. The HRRR and the NAM Nest develop supercells either over Sidney or Chadron NE indicating the locations of the most favorable environment for severe thunderstorms if they dont fall apart before then. The RAP also indicates some areas of weak isentropic lift along the Colorado/Wyoming border and into the southern Nebraska Panhandle as the evening progress. However, It also shows weak isentropic descent in the Northern Panhandle which makes it makes it a little harder to produce a supercell as potential drier air may entirely ruin the chances assuming the RAP was right. Although kind of conflicting signals depending on which models you look at, the areas to watch this evening would be either Sidney or Chadron for a potential severe threat that includes a tiny bit more than wind gusts greater than 60mph. It wouldn't surprise me if a storm does organize itself and drops the Intermountain west special of accumulating peas or potentially pennies with one or 2 quarter sized stones thrown in there. Monday is looking like a copy and paste forecast tomorrow. Looking at the WPC graphics the frontal placement remain quasi- stationary and the SPC has a marginal risk for tomorrow as well in the exact same place. Which honestly is fair when the catalyst is pretty much the same and the soundings show a tiny bit lower lcl's but the overall inverted v is still there but a tiny bit less CAPE values in the Panhandle with these latest runs... persistence forecasting may actually pay off. Monday still looks like a gusty shower/ weak thunderstorm type of day overall, but the potential for wind gusts to exceed 58 mph exists in our environment thus justifying the marginal severe risk. Especially when the model soundings have DCAPE values values around 1500-2000 joules in the afternoon and evening and the Rocky/Intermountain West region can produce those strong microburst like wind gusts at the drop of a hat. Temperatures and Dewpoints will be a little hard to forecast as the models are not doing a "good job" with the stalled boundary/dryline. They seem to be mixing out a lot more than whats actually happening and cloud cover seems potentially underdone which cooled us off a lot faster than the models anticipated thus the daily high temperatures being a little cooler than forecast. However, West of I-25 looks to still be in the 80's and east of I-25 will still be in the 90's with some areas still reaching 100. So in the grand scheme of things not much of a change in impacts as it still will be hot in the afternoon under this flatten ridge and the global models holding onto 700mb temperatures between 15 to 20C by the late afternoon.

LONG TERM /TUESDAY THROUGH SUNDAY/

Issued at 259 PM MDT Sun Aug 9 2026

As the long term forecast progresses, the 500mb jet moves from the Pacific NW to right over our area on Wednesday. While this jet has winds in the range of 50-60 knots, it is suppressed. As the ridge flattens, chances of moisture increase. PWAT values increase starting on Wednesday, with the highest values being Friday at around 1.5" near the Nebraska panhandle. RH values increase significantly on Thursday, ranging from 60-90%! This moisture sticks around through Sunday, even bringing some chances of thunderstorms with it. Shear increases Friday and Saturday evening, supporting chances of thunderstorms. Surface winds stay in a normal range for the area, typically staying below 35 knots. With this moisture moving in, and winds staying relatively slow, fire weather becomes much less of a concern through this long term period. 700mb temperatures show Wednesday still being quite warm, with much of the CWA being in the 15-17C range. Temperatures begin to cool down Thursday as a cold front moves in, bringing temperatures to the 10-12C range. The area stays cool through Sunday, below 13C.

AVIATION /00Z TAFS THROUGH 00Z TUESDAY/

Issued at 534 PM MDT Sun Aug 9 2026

A few strong thunderstorms in western Nebraska will impact BFF and AIA over the next 1-2 hours with strong, gusty winds, a brief VIS drop to IFR, and possibly some hail. Impacts may occur at SNY and CDR, but confidence is lower there. SE winds will stay elevated through the evening in the Nebraska panhandle, but should become lighter and occasionally variable later, though LLWS is possible at CDR.

Winds will turn northwest by late Monday morning across the area with gusts increasing in Wyoming. Look for another round of gusty showers and a few thunderstorms Monday afternoon.

CYS WATCHES/WARNINGS/ADVISORIES

WY...Air Quality Alert until noon MDT Monday for WYZ101>119. Red Flag Warning until 9 PM MDT this evening for WYZ417>433. NE...None.