textproduct: Cheyenne

KEY MESSAGES

- Mostly dry and warmer weather will prevail for Sunday through Wednesday, with thunderstorms possibly returning late in the week.

- Elevated to Near Critical fire weather conditions possible over east central Wyoming and the northern Nebraska Panhandle Monday afternoon.

SHORT TERM /THROUGH TUESDAY NIGHT/

Issued at 210 PM MDT Sun May 10 2026

Quiet conditions expected through the start of the work week, though that will lead to increasing warmth and elevated fire weather concerns. For the rest of today through Monday, expect warming to continue as ridging moves over the region, with highs shooting up significantly on Monday. Aloft, temperatures at 700 mb will peak between 10-13C, translating to highs at the surface in the upper 70's to upper 80's, with low 90's as we move into the Nebraska Panhandle. Many sites will be knocking on the door of record highs, so don't be surprised if a site or two at least ties the daily highs if we can get warm enough. Meanwhile this record warmth will also be in tandem with a notable lack of moisture as Relative Humidity values for the day descend into the low teens to near single digits. This will bring a widespread elevated fire weather concern, but at this time we have held off on issuing red flag warnings for various reasons. While winds will likely line up with these low RH values in Converse and Niobrara Counties, reports of greenup may be enough to hold off on issuing Red Flags at this time (though we are in contact with our fire weather partners on how true that may be). Meanwhile for the Nebraska Panhandle, winds are not currently expected to stay strong enough for 3 hours to produce Red Flag conditions. Looking again at 700mb, a quick hit of winds does occur during the afternoon into the evening, which may mix down, but this is for a brief period of 1-2 hours and struggling to increase winds using 90th percentiles to justify critical fire weather conditions. Will continue to message elevated concerns and pass this to incoming shifts to further analyze in case a last minute upgrade to Red Flag Warning is needed.

Into Monday evening and through Tuesday, a quick moving weak cold front will pass across the region, and should cool our highs on Tuesday back into the 70's to low 80's (though this will still be around 8-12 degrees above normal). This cold front should bring our temperatures down just enough that fire weather concerns should be low to perhaps slightly elevated, as some sites in the Nebraska Panhandle may see RH values bottom out in the upper teens for the day. The passing system will also bring a chance at a very isolated passing shower in the high terrain, but the risk remains minimal overall with a lack of more significant moisture as PWAT values remain rather dry at around 0.25 - 0.5 inch, alongside of course stronger forcing.

LONG TERM /WEDNESDAY THROUGH SUNDAY/

Issued at 210 PM MDT Sun May 10 2026

An upper level ridge will be centered over the New Mexico and Colorado area with an axis extending north over our area and into Canada. This kind of pattern should favor dry and clear conditions for much of our area. The daytime mixing of the boundary layer will dry out the surface while sinking air from the ridge will heat up the surface. Sampling the GFS model during the afternoon hours of Wednesday is indeed showing these conditions with a nearly 50 degree spread in surface temperatures and dew point temperatures. Maximum temperature will be flirting with daily record highs in some spots with widespread 80s and 90s. Relative humidities will drop into the teens and even single digits for areas in Carbon County. Surface trough development is being depicted in global models just to our north. During the afternoon a corridor of stronger flow to the southwest of this low will collocate with the driest conditions in Carbon and Albany Counties that afternoon. Sustained winds of 30 mph and higher gusts may be possible, though these details are murky being a few days out and depending on the strength of the surface low. Overnight humidity recoveries are expected to be poor for locations west of the Laramie Range. Regardless the pattern does favor elevated fire weather concerns at a minimum and interests should monitor conditions and forecasts for Wednesday and the next following days.

Thursday continues the dry conditions of Wednesday. We do see some monsoonal type moisture funneling in from the Gulf of California and the East Pacific that could be enough to create isolated showers and thunderstorms. PoPs are not high with current forecasts calling for around 20% chances at most. GEFS members give about a 20-40% chance of some areas in the CWA receiving 0.05" of rainfall. Given the fairly dry conditions at the surface most precipitation will evaporate on its way down from cloud level. The ridge axis that had been parked overhead the last few days should start to slide southeast, but dry and warm conditions will continue. Daytime temperatures may climb into the mid to upper 80s for areas east of the Laramie Range, with a slight cooling for the interior mountain regions. Relative humidity values remain low, in the teens, so fire weather concerns continue.

About this time a compact, high amplitude negatively tilted trough will be making its way in from the northwest. Compared to yesterday's guidance, the placement of this trough is trending southward and slower. The surface low that forms Wednesday may be tugged south to met this upper level trough during the day Thursday and Friday. We will likely remain on the dry side of this surface low. With the southward position of the upper level feature our high wind chances have decreased for Thursday, but gusty winds are still likely. Additionally, thunderstorm chances do not seem to have gotten better with this placement given the shut-off of surface moisture under the favorable portions of the jet, though details are still uncertain at this range. There was a slight increase in storm potential from machine learning models for the Nebraska Panhandle for what it is worth. The most likely outcome is a capped environment there.

Friday through the weekend portion of this outlook are appearing cooler following the departure of the upper level system. Another ridging pattern may setup for Friday and Saturday. Dry conditions continue with daytime humidity minimums dropping below 20%.

AVIATION /06Z TAFS THROUGH 06Z TUESDAY/

Issued at 1140 PM MDT Sun May 10 2026

VFR conditions will be in place throughout the TAF period as longwave ridging builds in from the west. A few high clouds will be present, but no low clouds/ceiling issues during this time. Winds are expected to remain variable in direction and below 10 knots through the overnight period, before our Wyoming terminals are expected to see winds ramp up after sunrise, mainly out of the WSW to around 15 knots. As we head into the afternoon hours, gusts are anticipated to increase to 25-30 knots as gradient flow strengthens thanks to weak lee cyclogenesis occurring to our north over South Dakota.

CYS WATCHES/WARNINGS/ADVISORIES

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