textproduct: Cheyenne

KEY MESSAGES

- Scattered strong to severe thunderstorms are expected once again on Tuesday, mainly in southeast Wyoming this time.

- All severe hazards including isolated tornadoes are possible today, but large, damaging hail remains the primary concern.

- Confidence is lower in strong to severe storms surviving into western Nebraska today due to a strong capping inversion.

- Numerous to widespread showers and thunderstorms are expected Wednesday through Thursday. Storms will have the potential to become strong to severe once again.

- Thunderstorms Wednesday and Thursday will also increase the flash flood potential, particularly over recent burn areas.

- Warming temperatures, falling humidity, and increasing winds will increase fire weather concerns Saturday onwards.

SHORT TERM /THROUGH WEDNESDAY NIGHT/

Issued at 230 PM MDT Tue Jun 23 2026

Another active day is on track for the area today as our stormy weather pattern continues. Last night, a moisture laden surface high pressure system surged westward across the area. Higher dewpoints have slipped west of the Laramie range, though a modest boundary is still apparent near the terrain. Further east, this cooler airmass has resulted in a very strong capping inversion setting up, with satellite imagery showing broken low cloud coverage holding strong northeast of a Wheatland to Pine Bluffs line. The cap has mostly broken down in Carbon and Albany counties by now, but it is still present in Laramie and Platte counties. Areas that are sunny now are expected to erode the cap over the next few hours, but those still in cloud cover may struggle to become uncapped at anytime this afternoon or evening. A modest jet streak remains overhead on the southwest flank of an upper level low well to our northeast. This is continuing to produce strong deep layer shear across the area, exceeding 50 knots in the 0-6km layer. Instability is a little weaker today compared to yesterday, with MLCAPE currently around 500 to 1000 J/kg expected to increase to around 1000 to 1500 J/kg by late afternoon. Overall, this sets the state for another round of scattered strong to severe thunderstorms today, but the risk area will be shifted to the south and west of where it has been the last few days.

Cumulus clouds are already going up in Albany and western Laramie counties as of this writing. This activity will make up the first round of thunderstorms, expected to primarily impact these two counties between now and 6PM or so. This may extend into southern Platte/Goshen counties as well as the southern panhandle, but there is lower confidence in storms surviving that far due to the strong capping inversion in place. Meanwhile, a second round is expected to initiate between about 4 and 6PM generally in northern Carbon county along the stalled moisture boundary in the area. This round will have the potential to develop into a longer track, discrete supercell thunderstorm and track to the east or southeast through the evening hours. Again, we should see this activity begin to weaken or struggle east of the I-25 corridor, and in particular, into western Nebraska. The primary hazards remain large, damaging hail especially with any discrete supercell thunderstorms that manage to develop. However, all severe hazards, including a few isolated tornadoes remain possible. Low-level wind shear is fairly weak right now, but this is expected to increase later this afternoon and evening with today's moisture return surging the stalled frontal boundary back to the south and west.

There is some concern for nocturnal, elevated convective activity tonight. Hi-res models are not showing this, but they traditionally struggle with this type of hazard. Overrunning lift on top of the frontal boundary will be occurring through about 4AM in place of elevated instability. Therefore, we are maintaining 20 to 40% PoPs through the overnight period once again. Tonight's fog will probably be fairly widespread with the strong moisture return. This was added to the official forecast. Confidence is too low for any Dense Fog Advisories now due to uncertainty in the exact location of the fog, but we will need to monitor this overnight.

Wednesday looks like another active day across the area. Following tonight's moisture surge, east to southeast flow will be present over the High Plains with plentiful low-level moisture pushing dewpoints into the 50s to low 60s. A vort-max will push in from the west over the top of an upper level ridge near the US/Mexico border. This feature will pull in abundant Pacific moisture in a pseudo- monsoonal surge. The combination of moisture from both sources will push precipitable water well above the 90th percentile of climatology, and even close to the 99th percentile. Low-level capping will be a concern once again over the High Plains tomorrow, but we are still expecting fairly widespread showers and thunderstorms to kick off early afternoon and spread eastward through the evening. Strong shear will remain in place Wednesday, supporting the potential for a few storms to become strong to severe. Expect much higher coverage of thunderstorms overall, but a similar risk for severe weather as not all of the storms will be strong to severe. Tomorrow will also add localized flash flooding back into the forecast due to the plentiful moisture and potential for multiple rounds of thunderstorms. The South Fork fire burn area is of particular concern. Forcing for lift will continue all through the night, which will likely keep a few showers and storms on the radar all the way into Thursday morning.

LONG TERM /THURSDAY THROUGH TUESDAY/

Issued at 230 PM MDT Tue Jun 23 2026

Thursday...Westerly flow aloft continues, and with surface low pressure developing over south central Wyoming producing a convergence axis from Douglas to Laramie, and plenty of low and mid level moisture, and 850/700 mb theta-e ridge axis from Casper to Cheyenne, along with CAPE of 1000 to 1800 J/kg and bulk shear near 50 knots, we anticipate some storms to become severe, with large hail and damaging winds as the primary threats east of I-25, with some locally heavy rainers due to flow aloft.

Friday...Low amplitude ridging develops over our forecast area, with some drier air noted advecting in. However, still expect isolated to widely scattered afternoon and evening thunderstorms to form along a low level convergence axis along the I-25 corridor. A few strong and possibly severe storms may occur.

Saturday...The flow aloft turns southwest and increases in speed, with considerably drier air moving across our counties, producing a dry day with a warming trend as 700 mb temperatures spike near 19 Celsius.

Sunday through Tuesday...A broad trough aloft develops across the northern and central Rockies, with dry southwest flow aloft, leading to only isolated to widely scattered thunderstorms at most in the afternoons and evening. Slightly cooler compared to Saturday in the wake of a cold frontal passage.

AVIATION /00Z TAFS THROUGH 00Z THURSDAY/

Issued at 552 PM MDT Tue Jun 23 2026

Scattered thunderstorms have developed over Southeast Wyoming and slowly pushing east into the Panhandle. However, KBFF looks to possibly get a storm maybe around 0400z. These storms are kind of pulsy so its unsure if they hold up and keep the same intensity or fall apart. Low clouds look to develop overnight but unsure if any fog will develop with the low clouds as well. But the low clouds should burn off around 15z tomorrow. And then we can start this all over again with storms around 21z.

CYS WATCHES/WARNINGS/ADVISORIES

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