textproduct: Cheyenne

KEY MESSAGES

- Another critical fire weather day on Friday alongside gusty, dry showers and/or dry thunderstorms possible.

- Quick cool down on Saturday with temperatures warming again on Sunday followed by an early week cooling period Monday and Tuesday.

- Increasing moisture should lead to precipitation chances over the weekend followed by daily shower and thunderstorm chances next week.

SHORT TERM /THROUGH SUNDAY NIGHT/

Issued at 230 AM MDT Fri Sep 11 2026

Forecast will ebb and flow over the next several days as we see temperatures oscillate up and down and moisture chances increase through the weekend. Aloft, we'll see more zonal flow return today with an increasing low-level jet and mid level moisture returning, with a quick shortwave disturbance moving across the forecast area. On Saturday, this pattern should continue, but a transient ridge will overtake moving into early Sunday, but by the afternoon and evening a Pacific Low swinging inland will start to encroach the forecast area by late in the period into early Monday. At the surface, troughing and a cold front will pass across our area today, with this front lifting back up as a warm front Saturday evening, and then dropping back down across the forecast area Sunday into Monday.

For today, this pattern will produce notably warm daytime temperatures east of the Laramie Range, with highs between the 80's to 90's (meanwhile a much cooler day expected to the west with highs in the 70's). While mid level moisture does begin to move into the area, low level moisture will remain lacking, with critically low relative humidity values expected yet again alongside gusty winds. Because of this, a Red Flag Warning is once again in effect across the region, but this time primarily for our eastern zones including Cheyenne and surrounding fire zones alongside the Nebraska Panhandle. Further west, while winds will be pretty gusty and sitting just under High Wind Warning criteria, RH values are expected to be a bit higher alongside the cooler afternoon temperatures, at least enough so to keep this area just outside of critical criteria (though elevated fire weather conditions are still anticipated). Finally, we should see the return of clouds alongside the potential for some showers or storms, but with inverted V profiles from the dry low levels, anticipating most of this activity to struggle to reach the surface, with gusty virga or dry thunderstorms the most likely activity for the day.

On Saturday highs should drop down into the 70's to 80's, with locations west of the Laramie Range actually a little warmer overall as it remains just outside of the cold front which should be hung up on the high terrain. While surface profiles will be slightly more moist, we should continue to struggle to produce more noteworthy precipitation, with only slight chances of another batch of showers and storms. But then into Sunday as more moisture arrives we should finally have the return of noteworthy precipitation on the day. PWAT values should climb in excess of 175-200% of normal, roughly equivalent to 1-1.3 inches. While instability will be low to moderate overall, shear should actually be pretty fair to good for the day, with bulk shear values of 50-60 knots possible. So not only should we see storms with decent rainfall potential, severe storms cannot be ruled out as well with gusty winds and large hail possible, primarily along the eastern Wyoming border through the Nebraska Panhandle. Finally, 850 mb Craig to Casper pressure gradients for the day exceeding 50m will be close to giving us our first high wind event of the fall, but expecting our breeziest locations to remain just under criteria, likely around 50-55 mph. In house random forest model guidance agrees with the above wind outcome, with Rawlins the closest to nearing high wind warning criteria at 40%. That being said, with how Wyoming is, don't be surprised if we do get a site or two nearing or reaching 60 mph gusts.

LONG TERM /MONDAY THROUGH THURSDAY/

Issued at 235 PM MDT Thu Sep 10 2026

On Sunday an upper level system makes its way into the PNW. Guidance is showing the potential for storms with this return flow ahead of the upper level system's passage. The main risk area for these storms is east of I-25. Sunday night into Monday morning shows a cold front passing over the CWA. After this front moves out, a ridge starts to build, bringing cooler temperatures and dryer air. Some storm and shower activity is possible Tuesday evening with return flow. A shortwave passes through on Thursday evening, allowing the ridge to continue to build. 700mb temperatures are in the 10-15C range in this long term period. Temperatures start to cool off and feel more like fall as the week progresses.

AVIATION /12Z TAFS THROUGH 12Z SATURDAY/

Issued at 534 AM MDT Fri Sep 11 2026

VFR conditions expected over the next 24 hours. Winds will be the primary concern as gusty conditions from the W to NW between 20-40 knots expected, with winds lessening during the nighttime hours and turning more N to NE'ly for Nebraska terminals, or becoming light and variable for WY terminals. Cloud decks will continue to be mid to high level, generally at SCT to FEW through the course of the day. While there is a chance of a shower or storm, those probabilities remain too low to include in the TAFs, though any precipitation near sites could cause gusty and erratic winds.

CYS WATCHES/WARNINGS/ADVISORIES

WY...Red Flag Warning from 11 AM this morning to 7 PM MDT this evening for WYZ429>433. NE...Red Flag Warning from 11 AM this morning to 7 PM MDT this evening for NEZ434>437.