textproduct: Cheyenne

KEY MESSAGES

- High Wind Warnings and Red Flag Warnings remain in effect through 6 PM today.

- A cold front will bring a chance for light snow to the High Plains Tuesday evening.

- The cold front will also bring the potential for another period of high winds along the wind prone areas of I-80 Tuesday afternoon and evening.

- A widespread, locally damaging wind event is still on track for Thursday. Widespread gusts of 60 to 80 mph are possible, with potential for localized gusts up to 100 mph in the wind prone areas of southeast Wyoming.

- Very strong winds are expected to continue through at least Saturday ahead of the next chance for precipitation Saturday into Sunday.

SHORT TERM /THROUGH THURSDAY NIGHT/

Issued at 400 PM MDT Mon Mar 9 2026

Wind and fire weather will be the primary weather concerns for most of the forecast period, but we will get a brief break on Tuesday as a cold front passes through.

Currently, a zonal flow pattern remains entrenched across the northern tier of the CONUS. The upper level jet stream and associated thermal gradient are located to our north over Montana and into the Dakotas. Further south, we are back to the usual warm, dry, and windy over most of our area. Temperatures have surged into the 60s or even low 70s across the High Plains, with a few record highs possible before things start cooling this afternoon. A surface trough is positioned along the I-25 corridor with the lowest MSLP over east central Wyoming this afternoon. Pressure increases rapidly to the north heading across the stationary front boundary. A vort- max moving through the flow aloft will begin to pull this surface low eastward over the next few hours, causing cross-barrier pressure and height gradients to begin to drop. As a result, we will see winds starting to decline here shortly, and High Wind / Red Flag Warnings should be able to expire on time at 6PM this evening. Cooler air with better moisture will fill into the High Plains behind this front, leading to good RH recoveries tonight, with the exception of Laramie County. We may also see a few showers develop this evening as the front pushes southward.

The front will stall somewhere around a Casper to Pine Bluffs line, with cooler and more moist air in place for Tuesday north/east of that boundary, and warm and dry weather continuing to the southwest. Expect the stalled boundary to retreat slightly during the day Tuesday, perhaps to roughly a Lusk to Kimball line. By Tuesday afternoon, a stronger shortwave aloft will begin to traverse through the northern Rockies. As this feature strengthens, it will dig southward, and help push the stalled boundary into Colorado. Vorticity advection aloft will help support the development of rain and snow showers over the High Plains Tuesday afternoon and evening as the front moves through. These will be rain initially, and then change to snow as colder air moves in behind. Both lift and moisture are unimpressive with this event, so forecast precipitation totals are modest at best. Still, some light snow accumulation is possible mainly along the US-20 corridor from Douglas to Chadron. Ensemble median QPF around Chadron is 0.15", which would lead to around 0.5 to 1" of snow depending on how much can manage to stick. At the high end of the ensemble spread, a Winter Weather Advisory could be needed for the northern Nebraska panhandle, but the probability of this is only around 10% at this time. In addition to the snow showers, the passing cold front will have a narrow region of stronger 700-mb winds concurrent with potent subsidence along the mid-level frontal boundary. Expect this to lead to a brief surge in winds along and behind the front, mainly for the I-80 corridor between Cheyenne and Rawlins. The wind direction will be poorly aligned to get strong winds in the Bordeaux area. In addition, pressure gradients are oriented in an unusual direction, which makes most of our typical wind parameters fairly unreliable. Still, most model guidance shows strong MSLP gradients over the I-80 corridor, and NBM guidance depicts a ~60% probability for gusts exceeding 60 mph in the Arlington area, and around a 30% probability for the I-80 summit. This event is more marginal and low confidence, but a High Wind Watch was issued for Tuesday afternoon through Tuesday night for just these two wind prone areas.

Wednesday will be a cooler day across the area, but unfortunately also much drier. NAEFS mean precipitable water is below the 10th percentile of climatology across most of the area. So, despite temperatures finally cooling to near average over most of the area, the extremely low dewpoints will keep fire weather concerns going as the wind continue. High winds are not particularly likely on Wednesday (30% probability in the wind prone areas, less than 10% elsewhere), but it will be a widespread breezy to windy day. Even if High Wind headlines are not needed, we may need Fire Weather headlines as it approaches due to the very dry air and widespread winds gusting 25 to 40 mph.

This will lead us into the main event beginning Wednesday night. A powerful 150+ knot upper level jet streak will nudge off to the northeast Wednesday evening, putting our area underneath the subsident right exit region of the jet streak aloft. Meanwhile, a powerful shortwave trough will ride along the international border, carrying behind it an extremely strong 700-mb jet and boosting the low-level height gradients. LREF mean 700-mb winds climb close to 60 knots over KCYS by early Thursday morning, and remain there into Friday morning. Ensemble mean 700-mb winds are exceeding the 99.5 percentile of climatology across most of Wyoming and Nebraska. The ECMWF Extreme Forecast Index generally ranges from 0.9 to 0.99 across the area, which indicates high confidence in an unusually strong wind event. The shift of tails index around 1.0 in southeast Wyoming suggests that several ensemble members are exceeding the climatological maximum 700-mb wind speed. In addition to the powerful 700-mb winds, low-level height gradients are not quite off the charts yet, but are nearly universally in the top tier of wind events for our area. Forecast soundings also suggest the development of stable inversion layer right around 700-mb, which coincides well with mountain top height of the Laramie Range. Wind speeds are either steady or even decrease with height above the inversion layer, which will set the stage for vertically propagating and breaking mountain wave activity. Thus, downslope acceleration will be on the table. All together, high winds in the wind prone areas are a near certainty, with probabilities around 80% for adjacent areas of southeast Wyoming. Even into far eastern Wyoming and western Nebraska, most of the area currently has a greater than 50% chance for winds exceeding 60 mph on Thursday. Even the NBM, which typically is conservative on high winds for our area, depicts a 30% probability for wind gusts exceeding 90 mph in the typical wind prone areas. Probabilities are even higher in northern Platte County between Wheatland and Glendo which can put up the highest numbers during mountain wave high wind events. As a result, confidence is very high in a widespread high wind event, and moderate in this becoming an upper tier wind event (e.g. 80 to 100 mph in the wind prone areas, 65 to 80 mph elsewhere). Even though we are still several days out, decided to issue a High Wind Watch beginning Wednesday night due to the potential severity of this event.

As has been the case numerous times this season so far, the extreme winds will be accompanied by temperatures pushing 20F above seasonal averages. While dewpoints should improve slightly for Thursday, Relative Humidity forecasts remain in the 15 to 25% range due to the warming temperatures. Even if we don't quite hit critical RH values, the magnitude of the winds suggest the potential for widespread dangerous fire weather conditions. Fire weather concerns were included in the messaging with the High Wind Watch product, but additional fire weather products will likely be needed for this period. Wind driven grassland wildfires will have the potential to spread very rapidly. High winds will continue for several more days after Thursday also, but this will be described in the Long Term section below.

LONG TERM /FRIDAY THROUGH MONDAY/

Issued at 400 PM MDT Mon Mar 9 2026

Friday starts a series of shifts in the upper level flow as we transition from Northwesterly flow from the trough that pushed through Thursday into a brief westerly flow. The high winds continue to remain as the 700mb speeds continue to be around 65 to 70 knots aiding in mountain wave continuation. Looking at a regional GFS cross section the question remains is how fast will the winds be at the surface. Those surface winds depends on if the mountain wave breaks and where does this breakage occur. The cross-section shows possible mountain wave breakage early Friday morning however the stability and parcel buoyancy looks to shift around mid-morning to favor the continuation of the wave without breaking. Even though daytime mixing will help bring those faster winds down to the surface as well, the strongest winds look to Friday morning when that Mountain wave breakage is likely to occur. These high winds look to continue into the weekend as well. Saturday night into early Sunday morning another trough impacts the Intermountain West. This trough will be responsible for switching our flow from the westerly flow back to a more Northerly flow. Cluster analysis shows the ensembles still show some uncertainty with how deep this trough will dig into our area. This is mainly due to the positioning of the highly amplified ridge that is progged to form off the West coast and shift eastward Friday through Sunday. A strong ridge that shifts more east during this time will prevent much of that Northerly transition and keep us dry as the trough remains shallow preventing the moisture from reaching us. However, if the ridge remains amplified over the West coast then the trough will be able to dig much further as the Intermountain West will be on the front side of that ridge transition to Northerly flow. The latter scenario will result in greater precipitation chances and the pull of colder air dropping in over the region for cooler temperatures on Sunday and possible snow chances. The positioning of this ridge will be the key factor in the continuation of high winds as well. This is mostly because if a strong ridge moves over the Intermountain west then it would push the jetstream more northward giving us a break but also making us drier as well. Keeping us in Northerly flow would keep the jetstream over us as it climbs over the ridge on the west coast and like a roller coaster accelerating on the downward side (front) but also allowing for more systems to graze the region and potentially increase our precipitation chances. Right now the global models are showing that ridge shifting eastward about Tuesday giving us a cooler Sunday and Monday with decreasing precipitation chances after Monday morning and potential continuation of high winds at the start of next week.

AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/

Issued at 550 PM MDT Mon Mar 9 2026

There looks to be some residual wind shear overnight mainly for our Wyoming terminals between 40 to 50kts. Some mid to high based clouds are going to be passing through overnight as the winds calm down after 03-06z. There may be some brief rain showers accompanying those lower clouds mainly near KCDR but there is low confidence in that. However, after 18z the clouds will start to lower with the arrival of a shortwave moving from North to south. KCDR will be the first with every terminal being under overcast skies under 10,000ft by 00z. Showers look to arrive at KCDR between 23z Tues and 03z Wednesday. These showers look to affect the Nebraska Terminals more but are still possible for KLAR and KCYS after 06z Wednesday.

CYS WATCHES/WARNINGS/ADVISORIES

WY...Red Flag Warning until 6 PM MDT this evening for WYZ417-418- 430>433. High Wind Warning until 6 PM MDT this evening for WYZ101-106- 110-116-117. High Wind Watch from late Wednesday night through Saturday evening for WYZ101-104>107-109-113-115>118. High Wind Watch from Tuesday afternoon through late Tuesday night for WYZ110-116. High Wind Watch from Wednesday evening through Saturday evening for WYZ110. NE...Red Flag Warning until 6 PM MDT this evening for NEZ434>437.