textproduct: Cheyenne

KEY MESSAGES

- A Marginal Risk for strong to severe thunderstorms expected this afternoon and evening. Strong and possibly damaging winds and heavy rainfall are the primary concerns, though large hail is still possible.

- A Flash Flood Watch has been issued for the South Fork burn scar area due to the potential for multiple rounds of thunderstorms with heavy rainfall in the vicinity.

- Warming temperatures, falling humidity, and increasing winds will increase fire weather concerns this weekend into early next week.

SHORT TERM /THROUGH FRIDAY NIGHT/

Issued at 217 PM MDT Thu Jun 25 2026

Tonight...Severe Thunderstorm Watch in effect until 8 PM MDT for all southeast Wyoming counties. WSR-88D and visible satellite imagery show a healthy cluster of thunderstorms forming just northwest of our forecast area in western and central Wyoming. Models have consistently shown a northeast to southwest oriented line of showers and thunderstorms affecting Carbon and Converse Counties late this afternoon, with the line of storms propagating southeastward through the evening across our counties.

Impressive 850-700 mb and 700-500 mb theta e ridge axis resides in the clearing ahead of the line and shortwave trough approaching will help ignite a nearly unbroken line of thunderstorms. HRRR has consistently shown this well, and thus we have high POPS timed well thanks to coordination between our midnight and day shift Meteorologists. Main threats from the thunderstorms will be strong outflow and straight line winds, with hail and locally heavy rain as a secondary threat.

After the line of thunderstorms passes, widespread low clouds and fog will develop east of I-25 again in the moist upslope flow.

Friday...One more day of possible severe thunderstorms Friday afternoon and evening, as a healthy 850/700 mb theta-e ridge axis forms north to south across far eastern Wyoming and the Nebraska Panhandle. Concur with the Storm Prediction Center Marginal risk for severe storms east of I-25 due to impressive CAPE of 2000 to 3000 J/kg, and somewhat limited bulk shear values near 35 knots.

Synoptically, a shortwave trough aloft will lie across eastern Wyoming near peak heating, with deepening surface low pressure across central Wyoming, and a decent low level convergence axis developing in the afternoon from Casper to Cheyenne.

Friday night...After residual evening thunderstorms across the Nebraska panhandle move off to our east, clearing skies and quiet weather will ensue.

LONG TERM /SATURDAY THROUGH THURSDAY/

Issued at 217 PM MDT Thu Jun 25 2026

A large upper level trough will set up shop over the Pacific Northwest at the beginning of the long term. The western lobe of this trough is favored to have more vorticity and energy. This vorticity lobe will swing south and north while becoming negatively tilted as it move over our area Monday. We would typically expect unsettled weather with such setups, however it appears the dryline will be too far east, shutting off our access to moisture for widespread rain.

Saturday the dryline will mix well east of the area by midday. Following the passage of the line winds will increase from the southwest and humidity will plummet. Minimum humidities will be at or below 20 percent area wide with gusts to 30-45 mph. Some elevated fire concerns could materialize from these supportive conditions. This would impact our western counties the most, however fuels are still green in the latest reporting. The SPC has given this area 30- 70% chances of low relative humidities and gusty winds through the entirety of the long term. Therefore, elevated fire weather concerns will stay with us for awhile.

There is a chance of some strong thunderstorms along the dryline as it mixes east Saturday afternoon. The machine learning guidance is highlight a risk in the Nebraska Panhandle regions. The current thinking is the dryline will be too far east, but if the line does stall more west we could see a few storms go up before leaving the CWA quickly.

Sunday a cold front associated with the aforementioned trough will make its way through the area. A slight uptick in precipitation probabilities is anticipated mainly for the northern portions of the CWA, though widespread rain is unlikely. GEFS ensemble members have between a 40-70% of points receiving any measurable rainfall. Following the frontal passage we stick with a dry and warming trend. Highs creeping into the 90s west of I-25 by Thursday. Gusty winds will continue to no ones surprise. It probably will not be until Wednesday or Thursday that moisture makes its return to our most eastern counties. A few dry storms could then be allowed to develop with enough lifting from the persistent but disorganized troughing to our west.

AVIATION /06Z TAFS THROUGH 06Z SATURDAY/

Issued at 1111 PM MDT Thu Jun 25 2026

Some low clouds and fog are forming in the Nebraska Panhandle and the visibility will probably bounce between 1sm to 3sm all night in the fog. Some areas may briefly dip lower than 1sm but it probably wont last long when it does. The Wyoming terminals are expected to stay in vfr as mid level clouds between 8,000 and 10,000ft move through the area before clearing in the morning. Another round of scattered thunderstorms are expected around 20z for Wyoming and after 00z for the panhandle before clearing out by 04z.

CYS WATCHES/WARNINGS/ADVISORIES

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