textproduct: Western and Central Wyoming

KEY MESSAGES

- Record breaking heat will persist across the region through the remainder of the week and into the weekend. All-time March high temperature records are in jeopardy of being broken by multiple degrees over the next few days.

- Widespread critical fire weather conditions will be a daily occurrence across nearly all of the lower elevations locations east of the Divide through Saturday evening.

- Rapid snowmelt is expected to occur across the higher elevations during the daytime, which will likely lead to increased water levels. However, the overall concern for flooding remains low at this time.

- A cold front will bring some cooler temperatures for Sunday but highs are still expected to be 10 to 15 degrees above normal.

UPDATE

Issued at 129 PM MDT Wed Mar 18 2026

As of writing this, multiple locations have already seen preliminary observations indicating new daily record high temperatures. Location such as, Rock Springs and Big Piney are currently only 1 to 3 degrees off of tying or breaking all-time March high temperature records. That being said, there are still another 2 to 3 days with temperatures forecast to be even warmer. So there is a good likelihood of seeing numerous daily and all-time March high temperature records across multiple locations over the next few days. Otherwise, nearly all of the previous forecast discussion remains on track.

DISCUSSION

Issued at 131 AM MDT Wed Mar 18 2026

Thankfully, although it is rather breezy at the Riverton weather abode, it is much less than last night, when the balloon tried to rip my arm off. We still have a gusty wind, but with the jet further way and 700 millibar winds running 20 to 25 knots less, it should be manageable. We have passed another milestone in regards to heading out of spring, we now have more hours of daylight than darkness (we passed over 12 hours from sunrise to sunset yesterday), and many locations had their first 70 degree high of the year, including Riverton, Greybull, Casper and Lander (Worland had one earlier this month). And there will be more of that coming over the next four days.

The reasoning of the forecast remains similar to yesterday. And like yesterday, we will divide the discussion into discussing each concern.

FIRE...This one remains similar. With temperatures averaging 5 to 10 degrees warmer than yesterday and dewpoints fairly similar to yesterday, relative humidity will fall into the teens across much of the area. Just about all of the Red Flag Warning area has at least a 2 out of 3 chance of relative humidity dropping below 15 percent. With most areas having a gusty wind as well, the current highlights look good for today. I still have a few concerns about Thursday and Friday though. The humidity will definitely be there. However, the polar jet will move further north into Montana. This should decrease the wind somewhat, resulting in more sporadic critical fire weather. Some areas will hit as well so I won't try to split hairs at this point. Relative humidity recovery also looks rather poor, adding to the concern. Saturday also looks like a day of greater concern, as the pressure gradient tightens again ahead of an advancing cold front. Most guidance has slowed the progression of the front, so this could end up being the warmest day with more sunshine and any showers holding off until after sunset. Combined with low humidity, Saturday afternoon could be especially concerning. Concerns should ease for most areas Sunday, as the front brings cooler temperatures. However, there is a greater than a 1 in 2 chance of humidity near 15 percent across southern Wyoming even on Sunday, so some extensions to the highlights may be needed. We will cross that bridge later, if needed.

RECORD HIGH TEMPERATURES...We already had three record high temperatures, with Lander, Worland and Lake Yellowstone tying record highs. Highs today should average around 5 degrees warmer than yesterday, as ridging continues to build northward and thicknesses increase. Thursday and Friday look even warmer with some of our warmer locations like Worland and Greybull having a greater than 2 out of 3 chance of cracking 80 degrees for a high. There is one small change here though. It is that with the slower progress of the cold front, Saturday may turn out to be the warmest day, with most of the lower elevations east of the Divide having at least a 1 in 2 chance of high temperatures over 80 degrees. Chances of having a high over 85 have also increased, mainly around the Bighorn Basin, with a 1 out of 3 chance. It still looks highly likely (4 out of 5 chance) that we will see several all-time March record high temperatures fall this week, possibly as many as 3 times in some locations.

WIND...We still have some gusty wind this morning, but it is nothing compared to last night/Tuesday morning. The strongest wind is in the far western Cody Foothills, but these locations are not representative of most of that area and with no major roads has little impact. Much of the area still has a greater than 1 out of 2 chance of wind gusts over 30 mph today though. It will remain breezy Thursday and Friday, but with the jet retreating northward wind speeds should drop somewhat. Saturday looks like the other very windy day with the cold front dropping southward, with most areas having at least a 1 in 2 chance of wind gusts past 40 mph. High wind highlights may be needed for this day, but it is too early for those.

RISING RIVERS AND CREEKS...With the warm temperatures, some high elevation snow melt is likely over the next several days. However, impacts are expected to be minimal. For one, with the recent dry weather, the ground should absorb some of the water from the snowmelt. Also, with nights still somewhat long, mountain temperatures should fall close to or below freezing at night, slowing melt during that time. There will likely be some rises on creeks and streams, but few if any problems.

SUNDAY AND MONDAY...The aforementioned cold front may bring some showers Saturday night or Sunday, with the best chance across northern and eastern portions of the area with the best jet forcing. This system has little moisture to work with though, so any precipitation amounts would remain on the light side. The front will also knock temperatures down somewhat, but remain above normal. Temperatures then begin another warming trend, although not as warm as this week.

AVIATION /06Z TAFS THROUGH 06Z FRIDAY/

Issued at 1030 PM MDT Wed Mar 18 2026

VFR conditions expected throughout the entirety of the period remaining dry. Winds have diminished at all locations under mainly clear skies through the overnight hours. They will then increase after 15-19Z with daytime heating and mixing to the surface with CPR/COD/RKS up to 30kts and all other locations around 25kts. Winds will diminish after 01-02Z due to radiational cooling, with models indicating RIW will continue with the northwest drainage wind into the overnight hours into early Friday morning. Some high clouds the only other weather element to be had spilling over the ridge from the strong high to the southwest.

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

FIRE WEATHER

Issued at 131 AM MDT Wed Mar 18 2026

An extended period of elevated to critical fire weather is almost certain through at least Saturday. Relative humidity will fall into the teens across most locations in central and southern Wyoming the next four days. A gusty wind will occur on each of the next four days as well. The most impactful days look to be today and Saturday with the strongest winds, with the warmest temperatures likely on Saturday. Elsewhere, relative humidity should remain above critical levels. Red Flag Warnings are in effect for all zones where fuels are critical except for Zone 275, where humidity should remain somewhat higher.

RIW WATCHES/WARNINGS/ADVISORIES

Red Flag Warning until 9 PM MDT Saturday for WYZ276>283-287- 289.