textproduct: Cheyenne

KEY MESSAGES

- Elevated to Critical Fire Weather conditions expected again Tuesday as humidities dive into the single digit values with light winds. However, gusty microburst showers may develop in the afternoon.

- The potential for high winds will return Wednesday afternoon into Thursday. This may event spread outside of the wind prone areas.

- A cooler weather pattern with more frequent chances for precipitation will take over Thursday and last into early next week.

SHORT TERM /THROUGH WEDNESDAY/

Issued at 258 PM MDT Mon Apr 20 2026

The sort of broad ridge is still slowly pushing it's way east as forecasted. The apex of the ridge is expected to be over the Intermountain West on Tuesday before getting somewhat flattened by an incoming system. Unfortunately for us this ridge will keep the dry air and warm temperatures coming over the next few days. While the ridge apex is over our portion of the Intermountain west the winds will be relatively calm but the subsident flow also helps push dry air towards the surface. There will be a weak shortwave that will quickly push through Tuesday and afternoon and evening. Hi-res has some showers developing in Carbon and Albany county in the afternoon and slowly pushing east. However, looking at model soundings there is a very large inverted v-shape indicating a strong dry layer at the surface and with our light westerly winds that dry layer doesn't appear to saturate anytime soon. This means that any shower that does develop will likely produce virga and some gusty winds underneath it much like a dry microburst. Another day of the humidity in the low teens and single digits. Wednesday, The ridge will be pushing eastward over the Northern Plains as a deep upper level trough starts to push into the Intermountain West. This trough will gradually increase the pressure gradient over the Intermountain West leading to stronger and gustier winds as the day goes on. Wind gusts up to 45 mph will be possible east of the I-25 corridor in Southeast Wyoming while the Nebraska Panhandle winds will be a little lighter around 30 mph. Even though there is going to be a little bit of moisture advecting ahead of this trough RH values are still projected to be between 10 and 15 percent across the forecast area. The combination of gusty showers on Tuesday and increasing winds on Wednesday plus extremely dry conditions on both days has led to a new Red Flag Warning to go into effect 11am Tuesday through 8pm Wednesday as poor overnight recoveries are also forecasted Tuesday night.

LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/

Issued at 258 PM MDT Mon Apr 20 2026

A strong upper level low will traverse across the northern Rockies Wednesday night into Thursday. Models have come into better agreement on overall track of the low, which will keep the system to our north and thus put us in a fairly unfavorable position to receive widespread precipitation. Instead, our area is likely to be positioned on the windy side of the system, with more limited precipitation potential mainly confined to the mountains and perhaps Carbon and Converse Counties. There is still quite a bit of spread in the wind potential for this period. The GFS remains quite aggressive, and would indicate the potential for a middle to upper tier wind event. However, this solution is not yet the model consensus. Over Cheyenne, 700-mb wind speeds Thursday morning range from 41 knots at the 25th percentile up to 58 knots at the 75h percentile, which is quite the large spread for this lead time. The lower end scenario supported by the deterministic ECMWF and a fair number of ensemble members shows the upper level low considerably further north, over northeast Montana rather than northeast Wyoming. This keeps the strongest low-level height gradients to our north and would likely mean the high wind threat is confined to the wind prone areas. Current probabilities for winds exceeding high wind criteria are around 90% in the typical SE Wyoming wind prone areas along I-80 and I-25, 50 to 75% for SE Wyoming population centers including Douglas, Wheatland, Cheyenne, and Laramie, and 30 to 60% for remaining portions of the area including Rawlins, Torrington, and the Nebraska panhandle. Some form of high wind headlines will likely be needed for this event, but the extent of the hazard remains uncertain.

Regardless of exact wind speeds, expect a windy and cooler day Thursday as temperatures fall back to near seasonal averages behind a cold front. A secondary vort-max will rotate around the longwave trough, arriving Thursday afternoon into Friday. This will knock down temperatures further, with highs expected to be about 5 to 10F below seasonal averages for Friday. In addition, the upper level disturbance will bring increased chances for widespread light precipitation. While some light snow and/or rain is probable with PoPs in the 40 to 60% range, LREF probabilities for 0.10" or more of liquid precipitation is around 30 to 50% for most of southeast Wyoming, and 10 to 30% for most of western Nebraska. Concerning precipitation type, the chilly temperatures will support snow for the majority of those areas that manage to see precipitation.

Temperatures will remain chilly through the weekend. 700-mb temperatures will be near the climatological 10th percentile. LREF means are around -4C, but the interquartile range stretches from around -7C to -1C, indicating fairly low confidence in exact temperatures. The chill will be held in place by a broad, and unseasonably strong upper level low over the Canadian prairie, which will also keep the baroclinic zone over our area. Thus, expect the weather pattern to remain unsettled through this period. Another upper level low will move in across the western US and across the Four Corners states late Saturday into early Monday. This will take a more favorable track for widespread precipitation across our area. In addition, models are in fairly good agreement showing a surface high settling in over the northern Plains, allowing for an improvement in surface dewpoints and surface winds generally out of the south to east direction. For this system, LREF probabilities for 0.1" of precipitation or more are around 50 to 70% for the entire area. This drops down to 20 to 40% chance for greater than 0.25", and a 10 to 20% for greater than 0.5". Precipitation type will be a little more complicated with this event with the large spread in 700- mb temperature shown by various ensemble members. The warmer end would be rain for most areas outside of the mountains, while the colder end would be snow for almost everyone. The NBM may be a little on the cold side for snow levels for this event, but overall the most likely scenario is a rain/snow mix. High temperatures will be 10 to 20F below average through the weekend, with lows around 5 to 10F below average due to the increased cloud cover. The positive news of the cooler weather pattern is that we can expect a break from the fire weather concerns for several days, even if the precipitation fails to materialize.

AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/

Issued at 555 PM MDT Mon Apr 20 2026

Upper level ridge axis will remain nearly stationary over the Front Range over the next 24 hours and even strengthen a bit into Tuesday. Warm temperatures and dry weather will continue.

HAZARDS/WEATHER TRENDS: VFR conditions will continue over the next 24 hours with limited Aviation concerns. Lighter winds are expected into Tuesday with gusts up to 25 knots over KLAR and KRWL.

CYS WATCHES/WARNINGS/ADVISORIES

WY...Red Flag Warning until 8 PM MDT this evening for WYZ417-418- 430>433. Red Flag Warning from 11 AM Tuesday to 8 PM MDT Wednesday for WYZ417-418-430>433. NE...Red Flag Warning until 8 PM MDT this evening for NEZ434>437. Red Flag Warning from 11 AM Tuesday to 8 PM MDT Wednesday for NEZ434>437.