textproduct: Western and Central Wyoming

KEY MESSAGES

- Warm but more seasonable temperatures across the Cowboy State today

- Isolated showers and thunderstorms will be possible this afternoon and evening mainly over central and northern WY.

- Cooler temperatures arrive for Friday as a cold front moves through the state. Highs may be 10 to 15 degrees cooler than Thursday.

- The frontal passage will bring chances for showers and thunderstorms throughout the day Friday.

UPDATE

Issued at 1249 PM MDT Thu Jul 10 2025

Showers and thunderstorms that developed over portions of western and southern WY this morning have dissipated. Satellite imagery shows clearing skies with some isolated convection starting to develop over central and southern WY. Coverage will be limited mostly to east of the Divide and gradually spread to the east throughout the afternoon and evening. The main concern with any showers and thunderstorms will be strong gusty outflows of 50 mph or more. The atmosphere remains fairly dry which may lead to virga showers and an isolated dry thunderstorm or two. Temperatures are still on the warm side with highs in the upper 80s to low 90s east of the Divide and mid 80s west of the Divide. A cold front is nearing the state and is expected to start moving into the area by the late evening tonight.

The frontal passage is expected to bring cooler temperatures and chances for precipitation. Highs are forecast to be nearly 10 to 15 degrees cooler than Thursday. Temperatures east of the Divide will range in the mid to upper 70s with values in the upper 70s to low 80s west of the Divide. Shower and thunderstorms will be possible on Friday as the front passes with the best chances remaining across central and northern WY. Elevated PWAT values do look to possibly move into the region for Friday with above normal amounts mainly east of the Divide. This may create some brief heavy downpours but these are expected to remain fairly isolated.

The weekend sees warmer and drier conditions return to the area with highs reaching the upper 80s to low 90s. The next chance for precipitation does not look to arrive until the start of next week as a trough moves across the region. Another front moves through the area around Tuesday night bringing in a brief period of cooler temperatures. The remainder of the week looks to have increased chances for precipitation as multiple disturbances move through the region.

DISCUSSION

Issued at 120 AM MDT Thu Jul 10 2025

Weak showers will continue over the southern half of the CWA this morning, as a remnant low approaches the area from southern ID. Any rainfall amounts will be very low, a trace to 0.02", along with very isolated lightning strikes. Showers will remain isolated over this area through the rest of the morning after sunrise, as the low reaches far southern WY. The focus for precipitation will shift east of the Divide this afternoon, as the low exits over eastern portions of the state. Wind gusts of 50 to 55 mph will be the main threat, along with some lightning. Instability will be limited, as CAPE values will range between 200-500 J/kg. Temperatures will be about 10 degrees cooler across the CWA as a result of the passage of this remnant low. Fire weather conditions will remain elevated as well, with critical RH values returning to portions of the Wind River and Bighorn Basins and Sweetwater County.

A cold front will reach northern WY sometime between 06Z and 12Z Friday, quickly progressing southward and reaching the Divide by 15Z. Any precipitation looks to be confined to northern portions through much of the day Friday, but could progress into the Wind River Basin in the afternoon. Any thunderstorms look to occur along the Divide, due to the front. Highs in the 70s east of the Divide remains in the forecast, while areas west of the Divide stay in the low to middle 80s. Locations in northern Johnson County may not reach 70 degrees, which would be a 30 degree dip from yesterday.

Dry conditions then return for the weekend, with a somewhat northwest flow pattern aloft. This will lead to seasonal temperatures on Saturday and highs in the 90s return for areas east of the Divide on Sunday. Showers and thunderstorms could be possible Monday and Tuesday, as another trough drops south from British Columbia and bringing the trough/cold front through Tuesday night.

AVIATION /00Z TAFS THROUGH 00Z FRIDAY/

Issued at 335 PM MDT Thu Jul 10 2025

Models remain on track with the cold frontal passage overnight and Friday morning. There are slight indications of showers developing along and in the wake of the front, however, confidence is low. Most likely chances are at KCOD (30% chance), KWRL (20% chance) and KCPR (20% chance). Generally, the more likely impact looks to be lowering cigs at the aforementioned terminals. VFR conditions look to prevail, but for KCOD and KCPR, there is a 20-30% chance of MVFR cigs developing behind the front Friday morning.

Also with the frontal passage, northerly to northeasterly winds are expected at most east of the Divide terminals and at KRKS Thursday night through Friday morning. Gusts to 20 to 25kts are expected and could linger through much of the morning, though do look to gradually taper off at most terminals by the later half of the morning. Afternoon showers and thunderstorms will then be possible for east of the Divide terminals as clearing late Friday morning should prompt increasing instability into the afternoon.

Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for the latest information on smoke, icing, and turbulence forecasts.

RIW WATCHES/WARNINGS/ADVISORIES

None.