textproduct: Western and Central Wyoming

KEY MESSAGES

- Scattered rain showers and an isolated thunderstorm continue this evening across northern WY, including portions of YNP, the northern Absarokas, and the northern Bighorn Basin. Gusty downdrafts and strong outflow wind are the main threats.

- Abnormally warm temperatures are forecast for Wednesday with highs near monthly record high temperatures. Temperatures look to get into the 90s east of the Divide and upper 80s west of the Divide.

- Afternoon showers and thunderstorms will be possible Wednesday with the main concern being strong gusty outflow winds as well as dry lightning.

- Remaining warm and mostly dry Thursday through Saturday, with a cooldown back to about normal by Sunday.

UPDATE

Issued at 118 PM MDT Mon May 11 2026

Record high temperatures are expected across the Cowboy State today. Highs look to get into the mid to upper 80s east of the Divide and upper 70s west of the Divide. Most locations stay dry today with the only exception being far northern WY, where a few showers and possibly an isolated thunderstorm cannot be ruled out. The best chances (10-30%) will be across portions of YNP, the northern Absarokas, and the northern Bighorn Basin. Models have indicated a push of moisture later this evening, which may allow for precipitation to reach the surface in some locations. Overall, the atmosphere is likely too dry to see much moisture reach the surface. Strong gusty winds may be possible with these showers but at this time concerns remain minimal. The main focus shifts to Wednesday, where the heat really arrives with the potential for monthly May high temperature records to be met or even broken. Currently, models are showing 700 mb temperatures getting around 13- 16C which would translate to temperatures nearing 90 degrees at the surface. The locations most likely to see these temperatures would be central WY such as Fremont/Natrona Counties and portions of northern WY such as the Bighorn Basin and Johnson County. Other locations, likely see temperatures get into the mid to upper 80s. The concern remains for showers and thunderstorms during the afternoon Wednesday with the main hazard being strong gusty outflow winds. Otherwise, the forecast remains on track with little change for the end of the week into the weekend.

DISCUSSION

Issued at 1252 AM MDT Mon May 11 2026

The strong ridge that will control our weather for the next several days is noted on water vapor imagery across the southwestern US. This will lead to very hot, dry, and breezy to windy conditions through at least Wednesday. The ridge is being flattened slightly by a shortwave currently sliding east from southwestern Canada into the northwestern US. This shortwave will deal a glancing blow to Wyoming as it slides east through Montana and into the northern Plains Monday into Monday night. This shortwave will bring a weak cold front with it Monday night leading to a slight cooldown Tuesday. The ridge should amplify with a vengeance by Wednesday, with the hottest temperatures of the year, by far. Wednesday's high temperatures will reach the low to middle 80s F west of the Continental Divide and upper 80s to low 90s east of the Continental Divide.

Concerns for Wednesday include, the potential for dry thunderstorms and very strong downdrafts/outflows from convection. Mid-level moisture will be funneled in from the southwest as the ridge shifts east putting the area on the western side of the ridge. This mid- level moisture should be enough for isolated rain showers and thunderstorms Wednesday afternoon into Wednesday evening. A lack of low-level moisture due to very dry air remaining in place from earlier in the week will prevent much, if any, rain from reaching the ground. Model forecast soundings depict impressive inverted-v soundings across the area, with dew point depressions of 50-60 degrees. If this comes to fruition wind gusts from even little green blobs (very light rain showers) will have the potential to produce wind gusts of 50-60 mph at the minimum. The lack of precipitation reaching the ground will also lead to the threat of dry lightning. This will be discussed in more detail in the fire discussion below.

For Thursday and beyond the weather pattern becomes much less certain. There is good consensus on a fairly compact upper-low moving into the region, but the timing and exact location will be the difference between another hot and dry day on Thursday vs a cooler day with modest chances for precipitation. This probably won't be resolved until about Wednesday morning when this low finally comes onshore somewhere from Northern California to Oregon. Overall, expect it to remain warm, but be cooler from Thursday through Saturday. High temperatures these days will range from upper 60s to mid 70s west of the Continental Divide to mid 70s to low 80s east of the Continental Divide.

AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/

Issued at 956 PM MDT Mon May 11 2026

Prevailing VFR conditions continue through the TAF period, with mostly clear skies by Tuesday morning. A few rain showers over northern portions of the area linger for an hour or two to begin the period. Gusty downdrafts remain a threat with these showers. A cold front will continue passing through central portions of the area early in the period, but should stall along the Continental Divide early Tuesday morning.

Wind is northwest to northeast behind the front and will remain a bit breezy for most of tonight. Wind will increase again Tuesday afternoon, but will be much lighter than this past afternoon. The front will finally reach KRKS by 05Z Wednesday with wind shifting from the west to the east. Shortly thereafter this front will dissipate heading into Tuesday night.

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

FIRE WEATHER

Issued at 1252 AM MDT Mon May 11 2026

A strong ridge will keep skies mostly clear, with hot, dry, and breezy to windy conditions Monday through Wednesday. Monday and Wednesday are the days of greatest concern. Monday will feature high temperatures about 15 degrees above normal, wind gusts of 30 to 40 mph on average through the afternoon hours, and RH of 8 to 15% across all lower elevation zones. Tuesday will be a bit better east of the Continental Divide thanks to cooler air behind a weak cold front, but similar conditions to Monday will occur west of the Continental Divide other than wind being much weaker. Wednesday poses the widest range of threats as the ridge slides east positioning the area on the west side of the ridge. This will lead to mid-level moisture advecting in from the southwest. This coupled with very dry conditions persisting in the low-levels of the atmosphere will lead to possible (30%) dry lightning and very strong downdrafts from any convection that develops Wednesday afternoon. This convection could last well into Wednesday evening as well. This is in addition to the already expected breezy, dry, and very hot conditions on Wednesday. Beyond Wednesday the forecast becomes less clear, so keeping the focus on the next three days for fire weather concerns.

RIW WATCHES/WARNINGS/ADVISORIES

None.