textproduct: Western and Central Wyoming

KEY MESSAGES

- Above average temperatures continue across western Wyoming through most of the upcoming week in the 70s and 80s, possible record highs for this Monday afternoon in many areas east of the Divide.

- Warm temperatures, dry air, and breezy winds will lead to elevated to near critical fire weather concerns through the week. Red Flag Warnings are in effect today for portions of central and southern WY through 6PM.

- Above average temperatures and dry conditions continue through Saturday with relatively light winds. Next system pushes in late Saturday and Sunday bringing possible mountain snow and valley rain.

UPDATE

Issued at 100 PM MDT Mon Oct 5 2026

Little change to the short term forecast with temperatures pushing not only record high temperatures this afternoon but for the entire month of October. Highest confidence still reigns east of the Divide, mainly for the Bighorn Basin to Johnson/Natrona Counties. Otherwise, critical fire weather conditions still expected this afternoon as well. Not quite as warm but still above average for this time of year for the remainder of the week and into the start of the weekend. For the system late Saturday and into Sunday, models are better aligning with the deepening trough extending from a GOA low to the Pacific northwest. Where models diverge is whether it stays more closed or become a more progressive wave into early next week. This will determine how fast it pushes east and its longer term impacts to the CWA. This will mainly be mountain snow above 11-12kft and some valley rain. Any snow will remain above any of the western passes. Stay tuned for updated forecasts in the coming days.

DISCUSSION

Issued at 213 AM MDT Mon Oct 5 2026

H5 ridging continues to push the main storm track well to the north across the US/Canada border, leaving most of the Rocky Mountain Region dry and very warm. With temperatures running 10 to 15 degrees above normal, several record high temperatures are in jeopardy this afternoon. While ridging is in place, there is a weak trough passing by to the north, which will tighten the local pressure gradient. This will be enough to bring wind gusts up near 25 mph across the main wind corridor from RKs to CPR. With dry air already in place, this will bring fire weather conditions near critical this afternoon. Red Flag Warnings are already in place, and no adjustments will be needed there. The other note with this trough is that there's enough midlevel moisture to spark some virga showers early this afternoon across the northern tier of counties of WY. Chances for actual measurable precip are very low (<5%).

Tuesday will be similar to today, with ridging being the main feature, keeping temperatures well above normal. Winds will be lower, as the northern weather system moves east quickly, with relaxing gradient. There is another trough moving into Colorado from northern California during the afternoon, which may bring virga showers to the southern counties, but again, due to very dry surface air, chances for any accumulation remains very low (<5%).

The remainder of the week remains similar, with warm temperatures continuing under the ridge. The next considerable shift int he weather pattern still pointing to a deep trough digging along the Rockies this weekend, with colder temperatures and a much better chance for precipitation. As noted yesterday, models have been a bit quick bringing this trough in, with better chances leaning more toward Sunday.

AVIATION /18Z TAFS THROUGH 18Z TUESDAY/

Issued at 1130 AM MDT Mon Oct 5 2026

High confidence in VFR flight conditions through at least 18Z Tuesday. Winds remain 12 kts or less at most terminals. The exception terminals are KRKS and KCPR where breezy 15kt to 25kt winds are forecast through 01Z/02Z Tuesday. There is a very low chance (less than 15 percent) of a virga shower near KCOD through 22Z. Otherwise, expect only high clouds today.

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

FIRE WEATHER

Issued at 100 PM MDT Mon Oct 5 2026

Midday temperatures and winds have increased that will still bring the critical fire weather conditions from Sweetwater through eastern Fremont to Natrona Counties. Elevated to near critical west to east in other parts of the CWA. Near record to record temperatures this afternoon will yield low humidity values this afternoon in the 10 to 15 percent range, with gusty southwest winds 15 to 35 mph, highest in the areas of the Red Flag Warning through 6PM. Good RH recovery overnight as winds diminish towards sunset. The remainder of the week will remain elevated in fire weather conditions due to the low humidity but winds will remain relatively light.

RIW WATCHES/WARNINGS/ADVISORIES

Red Flag Warning until 6 PM MDT this evening for WYZ279-280- 289-300.