textproduct: Cheyenne

KEY MESSAGES

- Warming and drying trend expected through the end of the week.

SHORT TERM /THROUGH WEDNESDAY/

Issued at 155 PM MDT Tue Sep 1 2026

With a shortwave exiting Wyoming today, a few isolated showers and thunderstorms could pop up this afternoon. There is a bit of remnant monsoon moisture in the mid-levels, so moderate to heavy rain could be possible in any thunderstorms that develop. Severe thunderstorms are unlikely with MUCAPE barely maxing out around 500 J/kg. A few lingering showers could be possible overnight as moisture increases slightly in the mid-levels.

Wednesday will feature much of the same weather albeit a bit warmer and windier. With an upper-level ridge building over the eastern half of the country, areas east of the Laramie Range will see their temperatures rise by about 5 to 10 degrees compared to Tuesday. Most of the Nebraska panhandle will see highs return to the 90s, making for a warm start to September. While areas west of the Laramie Range may not benefit from the increased temperatures, they will see the wind. With an upper- level trough coming onshore of the Pacific Northwest, a weak 250 mb jet will be pushed into the CWA. Strong southwest flow will lead to a windy day across Carbon and Albany Counties with frequent gusts over 45 MPH likely throughout the afternoon and evening. Another weak disturbance moving across the CWA on Wednesday will spark another round of afternoon and evening convection. Once again, there will be very little instability and shear so severe storms are unlikely. Even heavy rain is less plausible with the monsoon plume weakening and PWATs dropping down to more typical values.

Looking at a dry and sunny day for Thursday as the ridge to the east strengthens. Temperatures will continue to rise, with highs a few degrees warmer than Wednesday. Conditions will remain breezy on Thursday as the CWA still sits under southwest flow. The breezy and dry conditions will lead to areas of increased concern for fire weather.

LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/

Issued at 155 PM MDT Tue Sep 1 2026

Friday...Although a bit of pseudo monsoonal moisture at mid levels will be over our forecast area, the deeper moisture on southwest flow aloft will remain over Colorado and New Mexico, thus continued dry for us. 700 mb temperatures suggest summer like heat will continue for warm weather lovers.

Saturday...Low and mid level moisture increases somewhat via precipitable water content, and the deeper moisture will create widely scattered showers and a few thunderstorms from the Laramie Valley to near Douglas and nearby locations in the afternoon and evening hours. Dry elsewhere. The decent 700 mb temperatures will aid in keeping similar temperatures to Friday.

Sunday...Beneficial rains look quite promising as there will be an increase in precipitable water values via a better monsoonal moisture tap. The combination of passing shortwave troughs aloft and low level mechanical lift and orographic effects will help produce scattered afternoon and evening showers and thunderstorms, most numerous over and near the mountains.

Monday...With adequate low and mid level moisture availability combined with upslope lift and passing shortwave troughs aloft, expect scattered afternoon showers and thunderstorms mainly over and west of Interstate 25, with the showers and thunderstorms propagating and developing mainly east of I-25 in the evening. Still some uncertainty with regard to maximum temperatures, as an early September cold front may pass across our counties bringing in a refreshing respite from the heat. With still so much uncertainty, will leave the warmer temperatures as is to blend in with our neighboring offices, but this day will likely be cooler than currently forecasted.

Tuesday...An autumnal like pattern greets us synoptically for September with a rather significant shortwave trough aloft traveling eastward across Montana. Still enough atmospheric moisture to produce scattered showers and thunderstorms south of a Rawlins to Scottsbluff line. Again, temperatures may be cooler than currently forecasted with later model runs and trends.

AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/

Issued at 1151 AM MDT Tue Sep 1 2026

A weather disturbance will move to the northeast of the region this morning, with mid level clouds clearing out in the wake of the disturbance. Quiet weather will prevail through the period.

Wyoming and Nebraska TAFS...High confidence in VFR prevailing. Scattered to broken mid level clouds will prevail through much of the afternoon, with decreasing cloud cover and scattered mid level clouds prevailing thereafter. Winds will be relatively light with minimal gustiness across western Nebraska, with gusty winds to 35 knots at KRWL, KLAR and KCYS through early this evening, and again after mid morning on Wednesday, due to gradient and mix down winds.

CYS WATCHES/WARNINGS/ADVISORIES

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