textproduct: Western and Central Wyoming

KEY MESSAGES

- Scattered showers and thunderstorms form between 1 PM and 3 PM Monday with stronger storms possible between 4 PM and 8 PM. The best chances for showers and storms will be across western, central, and northern Wyoming.

- A few strong to severe storms cannot be ruled out, with the main concerns being frequent lightning, strong wind gusts around 50 mph, and pea- to dime-sized hail.

- Another round of showers and thunderstorms Tuesday, although coverage will be less widespread. Chances further decrease Wednesday except across north-central Wyoming.

- Warm and dry conditions return for the second half of the week with record-breaking heat possible the weekend of July 11-12.

UPDATE

Issued at 1210 PM MDT Mon Jul 6 2026

Morning cloud cover has delayed cumulus growth Monday morning, but satellite imagery is showing clearing and more sunshine at midday. The shortwave responsible for the cloud cover was located over southeast Oregon late Monday morning, while high pressure was present over the Four Corners region. Southwest flow between these two features was funneling moisture northeastward across Utah into Idaho and Wyoming. This moisture feed continues through the evening and overnight hours as the shortwave slowly tracks to the Bitterroots tonight. The moisture and instability, owing to daytime heating, combine with some favorable jet dynamics to favor stronger convection later Monday afternoon and evening before slowly decreasing in coverage and intensity toward midnight Tuesday.

Showers and storms erupt between 1 and 3 PM Monday with stronger storms developing after 4 PM and persisting until 8 or 9 PM. Dewpoints have risen into the mid 40s to around 50 across the Bighorn Basin and I-25 corridor late Monday morning. This should set the stage for more robust convection later this afternoon across this region, which is highlighted within a marginal risk for severe thunderstorms in SPC's Day 1 outlook. The primary hazard will be strong wind gusts, although the increased moisture, at the surface and aloft, could lead to small hail east of the Continental Divide. The low dewpoints and inverted-V profiles across southwest Wyoming limit the threat to strong outflow wind even from weaker showers. Higher dewpoints and increased precipitable water values across mainly the north half of the state should allow for brief moderate rain with the stronger storms. Storm motion will be northeast around 25 mph. Drier air arrives from the west late tonight and Tuesday as the shortwave travels east through Montana. Coverage and intensity of showers and storms will be less Tuesday afternoon, although outflow wind will remain a hazard.

DISCUSSION

Issued at 243 AM MDT Mon Jul 6 2026

Sunday saw some of the warmest temperatures of the season so far across the Cowboy State. Portions of the Bighorn Basin flirted with the century mark, while central WY saw highs in the mid to upper 90s and locations west of the Divide hit the upper 80s to even 90F. These warm temperatures may be a brief hint at what could possibly be on the horizon. However, there is still a whole week of weather to address before that.

The work week will start with a nice break from the heat and possibly some precipitation across the CWA today. A weak cold front has worked its way across northern WY this morning and is likely to remain stationary over the northern portion of the state. The frontal passage has brought some cooler temperatures, but more importantly increased dewpoints mainly over northern WY. High temperatures are expected to get into the upper 80s to lower 90s east of the Divide and low to mid 80s west of the Divide. A shortwave will gradually start making its way across northern Idaho, portions of Montana, and northwestern Wyoming this afternoon and evening. This will begin to initiate convective development, while also slowly pushing in above normal PWATs to much of the area. A few isolated showers cannot be ruled out during the morning hours mainly over western WY. Convection really kicks off after noon, across western/central WY with showers and storms gradually spreading north through the afternoon and evening. Precipitation chances will be the greatest across western, central, and northern WY. Chances range from 20 to 40% for much of the previously mentioned area, with higher chances of 30 to 60% over northern WY. Drier air will likely hinder precipitation chances from Rock Springs to Casper. The Storm Prediction Center has highlighted portions of northern and central WY this afternoon/evening for a marginal risk (1 out of 5) of severe storms. The main hazards being strong gusty winds and possibly hail greater than 1 inch. The greatest instability will likely remain across northern WY, where dewpoints may near 50F. CAPE values look to range from 500 to possibly 1,000 J/kg over this area. Lesser CAPE around 500 J/kg will be across much of central and southwestern WY. The nearing shortwave looks to create some favorable 700-500 mb shear with values of 30-40 kts across portions of central and especially northern WY. Favorable steep lapse rates are likely to be in place leading to the potential for a strong to severe storm or two during the mid to late afternoon. PWAT values look to be nearly 100-150% above normal, so some storms especially across northern WY may be capable of producing a period of moderate to heavy rainfall as well. Overall, scattered showers and thunderstorms will be possible during the afternoon and evening mainly across western, central, and northern WY. The main concerns will be frequent lightning, strong gusty winds, small to large hail (~1"), and possibly a few moderate to heavy rain showers. One thing to mention is that dewpoint depressions across Sweetwater and portions of Natrona/Fremont County will likely be around 45-55F. This means if any storms do develop nearby, which does not look likely (10-20%), there could be a few strong gusty outflow winds of 45 mph or more.

Showers and weakening storms may linger after sunset, but should gradually dissipate through the late evening Monday into the early morning hours Tuesday. Some CAMs do show another round of light showers move through western WY during the early morning hours Tuesday. Currently, chances sit around 20-40% with lesser chances east of the Divide. Tuesday could see another day of scattered showers and thunderstorms, but the caveat being widespread above normal moisture. Some strong to severe storms cannot be ruled out with the main concerns likely being strong gusty winds and hail. Due to above normal PWATs, some minor flooding cannot be ruled out, especially in poor drainage areas. Temperatures Tuesday look to get into the mid to upper 80s east of the Divide and low 80s west of the Divide.

After Tuesday, models are trending towards a drier and warmer second half of the work week. Temperatures look to gradually warm back into the low 90s east of the Divide and mid to upper 80s west of the Divide. Some showers and thunderstorms cannot be ruled out Wednesday, but at this time chances for moisture look slim.

Long range forecast models have been hinting at this for a little while now and that "thing" is a rather anomalously potent ridge building over the western/central CONUS. While still nearly a week out, there is time for things to change but at the moment, there is good consensus among long range forecast models. Temperatures start to turn up Friday with current highs getting into the mid to upper 90s east of the Divide and upper 80s to lower 90s west of the Divide. Temperatures continue to soar for the weekend with probabilistic models showing a 30-70% chance for highs near or above 100F east of the Divide and 40-80% chance for highs around 105F for portions of the Bighorn Basin. Locations west of the Divide do not look to be spared with a 20-50% chance of highs to get into the mid 90s. There is certainly potential to see widespread daily high temperature records broken and the potential for all time high temperature records to be broken too. Overnight temperatures do not look to cool all too much with breezy winds keeping lows above 60 across locations east of the Divide. Overall, there is still time for things to shift and change. However, there is certainly an increasing potential for a record breaking prolonged period of heat. So unlike that one song, the dog days are not over, so you better be sure to check that A/C is working properly!

AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/

Issued at 414 PM MDT Mon Jul 6 2026

The majority of showers and storms end by 03Z/Tues. However, lingering showers, and a possible thunderstorm, continue across portions of western Wyoming through the night, with PROB30 groups kept at KCOD and KJAC. Most of these showers should be done by 08Z/Tues, but a few may linger as late as 12Z/Tues.

For Tuesday, storms begin to initiate around 19Z, with chances through the afternoon. Given the range out, have left PROB30 groups for now for sites with the best chances of isolated showers or storms.

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

RIW WATCHES/WARNINGS/ADVISORIES

None.