textproduct: Cheyenne

KEY MESSAGES

- Critical Fire Weather conditions expected on Saturday with gusty winds and low humidity values, with further critical conditions possible Sunday and again Monday as humidities dive into the single digit values.

SHORT TERM /THROUGH SUNDAY NIGHT/

Issued at 215 AM MDT Sat Apr 18 2026

High pressure will begin to build into the Rockies today as upper- level ridging takes hold of western CONUS. The ridge will begin to push cold air out of the region allowing warmer air to take its place. High temperatures on Saturday will be much warmer than Friday, however still below normal for this time of year. West of the Laramie Range, highs are expected to be in the 40s, while temperatures east of the range will be in the 50s. These highs will be roughly 5 to 8 degrees below average for mid-April. With the ridge building in, precipitation chances will be minimal, but cannot rule out a stray shower in the northern Nebraska panhandle as residual moisture and energy from the trough push out during the afternoon. Dry air will also be ushered in with the ridge, leading to rapid drying of the low-levels. The dry air combined with the blustery conditions expected today will lead to critical fire weather conditions for most areas east of the Laramie Range.

A return to above average temperatures is expected on Sunday as 700 mb temperatures climb above 0C. Highs will reach the 60s for most areas, leading to a pleasant day across the forecast area. With the approaching ridge axis, precipitation is not expected as sunny skies dominate. The approaching axis will also ensure that the low-levels stay extremely dry, with relative humidity falling into the single digits. This poses a concern for fire weather, however light winds under the ridge will limit any critical conditions.

LONG TERM /MONDAY THROUGH FRIDAY/

Issued at 241 PM MDT Fri Apr 17 2026

The work week will begin under the influence of a longwave ridge centered over the Rocky Mountain region, placing us in mid-level zonal flow. Unsurprisingly this will result in well above average temperatures, with locations east of the Laramie Range in the 70s and low 80s, especially in our Nebraska counties. West of I-25, temperatures will be slightly cooler in the 60s. Fire weather will be the main concern on Monday as median RH values are around 10% east of the Laramie Range per LREF guidance. Ensemble guidance also has median wind gusts of 20-25 mph, so combined with plenty of dry fuels given that our recent system didn't provide much in the way of moisture, fire conditions look to be elevated at this time. Have issued a Fire Weather Watch for area along and east of I-25 for this reason through Monday evening.

Not much change for Tuesday, except for slightly weaker winds which should decrease the fire concerns. RH values will also be slightly higher in the 15-20% range. High temperatures look to be a about 5 degrees warmer than Monday considering the ridge axis is progged to be located over SE Wyoming and W Nebraska. Not exactly threatening daily record highs, but temperatures should reach 20 degrees above climatology.

Wednesday the ridge begins to progress to the east, placing us in a southwesterly flow regime ahead of a closed low located over Oregon and Northern California. High temperatures look to remain similar to those of Tuesday, however given weak forcing for ascent downstream of the closed low, we may manage to see some high-based convection. Ensemble model soundings indicate inverted-v profiles, so wind is more likely than any beneficial rainfall. This is also consistent with ensemble median PWAT values which are around climatology, suggesting the overall lack of moisture.

On Thursday, the closed low progresses into an open wave and lifts off to the north and east of our area, bringing us a series of vorticity maxima along the base of the shortwave, providing some greater forcing for ascent. At the very least, this should increase cloud cover over Southeastern Wyoming and Western Nebraska. There is a slight increase in PWAT (0.05" more) relative to Wednesday, however the bulk of the moisture remains well to our north and east, so precipitation chances appear low at this time, so will keep low PoPs in the forecast. Given the increasing cloud cover, we can expect temperatures to be 10-15 degrees cooler than Wednesday's highs.

Ensembles are hinting at a cold front pushing across our area sometime Thursday evening into Friday morning, so Friday is expected to be much cooler than the rest of the work week. With the general lack of moisture along with quasi-zonal flow, beneficial precipitation unfortunately doesn't look to accompany this front.

AVIATION /18Z TAFS THROUGH 18Z SUNDAY/

Issued at 1121 AM MDT Sat Apr 18 2026

Breezy conditions expected across all terminals today with frequent north-northwest gusts to 30-35 knots. There is a scattered cumulus deck advecting southeastward across KCDR, KBFF, KAIA this afternoon, which are lowering ceilings to between 5 and 6 kft. This activity is slightly more expansive in coverage compared to earlier guidance, however is likely to diminish going into the evening hours. Visibilities are expected to stay above 6 statue miles throughout the forecast period. Overnight mid to high level clouds develop over the Wyoming terminals that make way to clear skies shortly after day break. Winds at the Southeast Wyoming terminals are to remain breezy with gusts to 25 knots out of the NW. The Nebraska Panhandle terminals will have light winds that may be variable in direction at times.

CYS WATCHES/WARNINGS/ADVISORIES

WY...Red Flag Warning until 8 PM MDT this evening for WYZ430>433. Fire Weather Watch from Sunday morning through Monday evening for WYZ417-418-430>433. NE...Red Flag Warning until 8 PM MDT this evening for NEZ434>437. Fire Weather Watch from Sunday morning through Monday evening for NEZ434>437.