textproduct: Cheyenne

KEY MESSAGES

- A Red Flag Warning is in effect for most of southeast Wyoming and the Nebraska panhandle today through Saturday evening. Critical fire weather conditions expected.

- Record warmth will continue Saturday with all-time record high temperatures for the month of March likely.

- Cooler, though still above average, temperatures return Sunday behind a cold front. Isolated showers possible with this frontal passage Sunday.

SHORT TERM /THROUGH SUNDAY NIGHT/

Issued at 245 PM MDT Sat Mar 21 2026

A *brief* pattern change arrives tonight in the form of a cold front. A weak shortwave moving across the US/Canada border will flatten the ridge over the Four Corners region enough for a cold front to sneak down from Montana. The cold front will be through most of the forecast area by midnight, with blustery northerly winds behind it as well as a slight chance for precipitation. Precipitation chances behind the front do not look promising as models continue to trend rather dry. Hi-Res guidance shows showers dissipating right along the northern CWA border, while synoptic models showing a whopping hundredth of QPF for the northernmost zones of southeast Wyoming and the Nebraska panhandle. At best, a sprinkle or light shower could sneak into the Pine Ridge area. Low stratus for areas east of the Laramie Range and in the Nebraska panhandle will be more likely than precipitation. Model soundings show a shallow saturated layer developing early in the morning. The HREF backs up the low stratus deck, showing pretty good probabilities of it occurring.

Temperatures behind the front on Sunday will be anywhere from 25 to 35 degrees cooler than Saturday. Despite the drastic cool down within 24 hours, high temperatures are still expected to be above average. Locations west of the Laramie Range will be the warmest with highs in the low to mid 60s. This will be about 15 degrees above average for late March. Areas east of the Laramie Range will see high temperatures in the 50s and low 60s, putting these temperatures only 5 to 10 degrees above average. However, these forecast highs could be cooler than anticipated depending on when low stratus clears out. Most models have the clouds clearing by the afternoon as dry air is quickly ushered back in by the upper-level ridge trying to rebuild itself. Clouds will once again build back in during the evening hours with the help of weak vorticity maxes aloft. Instability will grow over the Laramie Range which could produce a few light showers, or more likely, virga, given the dry environment. Hi-Res guidance is also keen on developing showers Sunday night, mainly in the vicinity of the Interstate 80 corridor, however, having a hard time believing these will manifest with the lack of moisture.

Temperatures will begin to warm back up on Monday as the ridge rebuilds. Despite there being some cloud cover, 700 mb temperatures will reach +6C which is about the 90th percentile for NAEFS climatology. Mixing will result in high temperatures returning to the 70s for areas east of the Laramie Range and mid 60s for areas to the west. Dry air will also be advected from the desert southwest, leading to a widespread return of relative humidity values in the teens.

LONG TERM /MONDAY THROUGH SATURDAY/

Issued at 245 PM MDT Sat Mar 21 2026

This persistent upper level ridge will keep building over our region going into Tuesday. Record high temperatures may be broken at some of the Wyoming Front Range sites as temperatures are likely to reach the mid to upper 70s, where records currently stand in the low 70s. Winds are also expected to increase as the 700mb pressure gradients begin tightening. Machine learning guidance is still highlighting elevated probabilities to 40 percent of high wind conditions in the wind prone areas. There are also 700 mb shortwaves being shown in model solutions, the passages of which could amplify winds if coinciding with peak mixing daytime hours or any mountain wave breaking.

Overnight Tuesday humidity recoveries will be poor, keeping already desiccated fuel sources receptive to fire spread. The Storm Prediction Center is highlighting a 70 percent Critical probabilities over a large portion of the CYS CWA. The conditions certainly match this outlook going into Wednesday, which looks the most concerning for impactful fire weather conditions so far. Relative humidity values are generally expected to be in the teens and high temperature likely to break records, some by almost 10 degrees.

Our next cold front has slowed down in today's guidance to next Thursday morning and there is notable divergence in its timing and strength. The trough associated with this front is flatter and less amplified in model guidance. The GFS solution is the most bullish in the strength of this front. If this is the correct solution then Friday may be cooler and more seasonable. However, if not, then much will be the same with above average temperatures. We will need to wait and watch guidance for any agreement as we get nearer.

To end this discussion on perhaps a happier note, in the very long term, past this forecast period, sees the possible breakdown of this stubborn ridging pattern. While too soon to work out specifics, ensembles are hinting at the return of the jetstream and wave breaking going into April. Fingers crossed this marks a return of wet and cooler conditions.

AVIATION /06Z TAFS THROUGH 06Z MONDAY/

Issued at 1133 PM MDT Sat Mar 21 2026

A cold front pushing south across the Nebraska Panhandle has turned winds to the north along with bringing gusts up to around 50 knots, which has been observed at KCDR. Expect this front to continue to push south over the next few hours and impact KSNY by 08Z with gust in the 30 to 45 knot range. These stronger winds with the FROPA will be short-lived and only continue for an hour or so after the front passes. A cloud deck with low CIGs is building across northern portions of the panhandle where KCDR has CIGs around 2,000 feet. This cloud deck will continue to push south towards KAIA and KBFF over the next few hours were CIGs there may too drop to near or less than 3,000 feet. CIGs should improve late overnight into Sunday morning, lifting and thinning. VFR conditions should prevail across southeast Wyoming while winds pose no threat to aviation operations for the duration of this TAF period.

CYS WATCHES/WARNINGS/ADVISORIES

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