textproduct: Cheyenne

KEY MESSAGES

- Critical fire weather conditions expected today alongside the potential for high winds.

- Much cooler on Tuesday with temperatures a few degrees warmer through the end of next week and daily chances of showers and thunderstorms.

SHORT TERM /THROUGH WEDNESDAY NIGHT/

Issued at 230 AM MDT Mon Sep 14 2026

Widspread lingering showers and thunderstorms across the region will continue to progress out of our area through the morning hours. Behind this activity as a cold front moves into our region and aloft a deep low spins across to our north with attendant troughing moving across the region, drier air will filter in behind it with PWAT values plummeting from around 1 inch to under or around a quarter. Meanwhile surface pressure gradients will remain enhanced, with Craig to Casper gradients around 50-55 meters at 850mb, and a low-level jet at up to 50 knots at 700mb. This will promote two potential threats for the day, the first of which will be possible strong to high winds. For now, have kept the High Wind Watch in effect and not upgraded because in-house guidance is still around or under a 40% probability our wind prone locations will see high winds, and most of the above guidance is just below what we would like to see for a Warning. Still, winds 50-55 mph are likely, and it wouldn't be surprising if a site or two reached 58+ today. Secondly, the dry air plus strong winds will promote a Critical Fire Weather environment, with Red Flag Warnings out across Southeast Wyoming and now into the Nebraska Panhandle. Otherwise, look for temperatures west of the Laramie Range to be quite cool as this area will remain behind the front, with 60's to 70's for the day. But to the east, it'll be another warm one with 70's to 80's.

This will change on Tuesday however as all zones will be behind the front. Highs for the day will only peak in the 60's to 70's giving a nice shot of fall air. Breezy winds from enhanced pressure gradients will remain, but not nearly as strong as today, and showers and thunderstorms should return alongside moisture, but strong to severe activity will be unlikely. Wednesday ridging builds back in and temperatures should warm back up, with highs in the 70's to 80's for the day. Similarly to Tuesday, another round of afternoon showers and thunderstorms is expected, but also similarly a lack of strong severe parameters will keep this activity sub-severe for the day. Pressure gradients will be relaxing as well, and gusty winds should finally subside for now.

LONG TERM /THURSDAY THROUGH SUNDAY/

Issued at 240 PM MDT Sun Sep 13 2026

Tuesday and into the weekend, the upper level low keeps migrating east into the Great Lakes and Hudson Bay region. The counter clockwise circulation will begin filtering cold air from the Arctic into the region undergoing some warming/modification as it pushes south over us. 700mb temperatures will drop between 8 and 12C translating daily surface temperatures into the cooler 60's and 70's and overnight temperatures into the 40's and 50's. Daily rainfall chances start to occur Wednesday as a train of Low pressure system system are expected to travel through the Pacific Northwest over the next 7 days. This precession of low pressure systems will push the ridge eastward into the central and southern plains leaving the intermountain west susceptible to multiple accompanied shortwaves but ahead and following each progged low pressure system.

AVIATION /06Z TAFS THROUGH 06Z TUESDAY/

Issued at 1050 PM MDT Sun Sep 13 2026

A Pacific cold front will gradually move across southeast Wyoming and western Nebraska later tonight through Monday. Expect showers and widely scattered thunderstorms to continue late this evening with another band of showers expected along the leading edge of the front early Monday morning. Low clouds likely and some fog expected across the eastern plains of western Nebraska. Gradual clearing after sunrise Monday morning.

HAZARDS/WEATHER TRENDS: Thunderstorm activity lingers across most of the area with another band of showers and thunderstorms moving into Carbon county, impacting KRWL over the next few hours through 07z. Gust up to 55 knots are possible with this line as it moves through KRWL and possibly KLAR later tonight. Otherwise, expect IFR to LIFR CIGS and VIS for KAIA and KSNY, with KCDR and KBFF in MVFR to near IFR CIGS until 14z. Do not expect these low clouds to get to KCYS, but can't completely rule it out either (<5% chance). Cold front will move across the whole area by late Monday afternoon with gusty westerly winds shifting into the north behind the front.

CYS WATCHES/WARNINGS/ADVISORIES

WY...Red Flag Warning from noon today to 8 PM MDT this evening for WYZ417>423-427-432-433. High Wind Watch from 6 AM MDT this morning through this afternoon for WYZ106-109-110. NE...Red Flag Warning from noon today to 8 PM MDT this evening for NEZ434>436.