textproduct: Cheyenne

KEY MESSAGES

- Shower and storm chances are expected through the rest of this weekend and later on Monday. Strong to severe wind gusts will be possible Sunday, with moderate to heavy rain possible Sunday and Monday.

- Marginal Risk for severe thunderstorms Sunday with strong gusty winds up to 65 MPH possible.

- Drying and warming trend expected going into mid to late week with growing potential for elevated fire weather conditions.

SHORT TERM /THROUGH MONDAY NIGHT/

Issued at 1153 AM MDT Sun Aug 30 2026

Another active day is in store for us mainly across Southeastern Wyoming, as another round of showers and thunderstorms is expected to develop across Carbon and Albany counties early this afternoon before pushing east. Our area will be located in the right-entrance region of a 90 knot 250 mb jet streak rounding the base of a potent negatively-tilted shortwave trough, setting the stage for large- scale forcing of ascent and more widespread coverage of convection.

Current visible satellite imagery shows quite a bit of convective debris from showers and even a few thunderstorms during the overnight hours. This should limit diurnal heating and hence destabilization into the afternoon which will put a restraint to the threat for large hail in any thunderstorms, which is similar to what we experienced yesterday. This is also confirmed via poor mid-level lapse rates (6-7 degC/km) as suggested by high-resolution ensemble guidance thanks to all the convective overturning. The primary threat will be damaging winds with any storms with forecast soundings showing inverted-v profiles and DCAPE values around 1000 J/Kg as a result of large surface dewpoint depressions and cloud bases around 2.5-3.0 km AGL. Further, any areas that do manage to experience some clearing and therefore heating and mixing will have the potential to mix down higher momentum air from the speed max aloft.

Today also features a marginal risk for excessive rainfall as noted by WPC, putting us in a level 1 of 4 risk for flash flooding. While surface moisture is rather meager with dewpoints in the mid to upper 40s across Southeastern Wyoming, overall total column moisture is more impressive, with PWAT values ranging from the 85th-95th percentile (around 0.9"), so heavy rainfall will be a threat. Due to the stronger flow aloft and forecast soundings indicating a cloud- layer mean wind of around 35 knots, showers and thunderstorms should move at a decent clip, so the flooding threat will largely be dependent on back building and training convection, primarily over urban areas. High temperatures today will remain around climatology for this time of year east of the Laramie Range with temperatures peaking around 80 degrees along the I-25 corridor, and upper 80s throughout the Nebraska Panhandle. Convection should come to an end this evening as the shortwave trough lifts to the northeast, limiting overall synoptic-scale forcing.

Monday will remain somewhat active as we remain on the western periphery of a rather flat 596 dam mid-level ridge, placing us in a southwesterly flow regime. This will allow for another surge of monsoonal moisture with PWAT values above the 90th percentile. Ensemble guidance shows another negatively-tilted trough lifting north and east out of the Four Corners region, placing us in a region of DCVA. HREF guidance isn't exactly excited about high rainfall totals, with probabilities of exceeding 0.1" of rainfall sitting between 10-15% mainly west of the I-25 corridor. Certainly see the potential for heavy rainfall with storms, however cloud- layer mean flow around 30 knots will keep storms moving and the flooding threat will be limited in areas of training and back building convection. Model soundings again are hinting at the potential for downbursts with any of the stronger cores given the lack of low-level moisture. Highs on Monday will be similar to today. Convection is expected to linger well into the overnight hours especially over the Nebraska Panhandle where the bulk of the forcing remains as the open wave lifts north and east.

LONG TERM /TUESDAY THROUGH SATURDAY/

Issued at 1153 AM MDT Sun Aug 30 2026

The long term period will feature a warming and drying trend as mid- level heights rise over our region and the bulk of any forcing for ascent remain to the north or west of our area. Tuesday will feature a slight chance of late day showers and storms as moisture remains trapped underneath the ridge and we remain in SW flow pattern (PWAT around the 70-80th percentile), however coverage is expected to be lower relative to today and Monday. High temperatures will again remain close to climatology, with highs in the 80s east of the Laramie Range and mainly 70s out west.

We begin to heat up on Wednesday and Thursday as the ridge axis becomes focused closer to the Northern Great Plains. This will turn our attention to potential fire weather concerns as long-range ensemble guidance has signals for gusty winds and daytime RH values ranging from 15-25% especially north of the I-80 corridor. Highs will peak in the upper 70s to near 80 degrees west of the Laramie Range on both days, with much of the Nebraska Panhandle soaring into the low to mid 90s, which is still a few degrees short of record highs.

As we end the work week and head into the weekend, the ridge begins to amplify and establish itself over the Central and Southern Great Plains, resulting in a containing trend of above-average temperatures and primarily dry conditions. There are some signals of an additional push of monsoonal moisture on Saturday and Sunday, however confidence isn't high enough at this time to mention any widespread precipitation for the region.

AVIATION /18Z TAFS THROUGH 18Z MONDAY/

Issued at 1109 AM MDT Sun Aug 30 2026

Primarily VFR conditions are anticipated through the forecast period, although scattered showers and a few thunderstorms will present some aviation weather concerns. The greater coverage of the showers will be across eastern WY, and higher wind gusts will accompany this activity. Confidence in impacts is too low to include tempo groups for the northern NE panhandle. Most showers should wane by 31/03z, and winds primarily turn light and variable for the NE terminals. Slightly breezy west winds will continue overnight for WY.

CYS WATCHES/WARNINGS/ADVISORIES

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