textproduct: Cheyenne

KEY MESSAGES

- The long duration high wind event will resume mid Wednesday morning in Carbon and Albany county, then spread into the I-25 corridor during the afternoon. Strong winds will last into Thursday evening.

- The wind prone areas along I-80 and I-25 can expect another round of wind gusts between 70 and 80 mph. A few gusts exceeding 80 mph are possible.

- Cheyenne, Laramie, Rawlins, and Wheatland can expect wind gusts between 60 and 70 mph, but occasional lulls or breaks in the high winds are expected with this round.

SHORT TERM /THROUGH THURSDAY NIGHT/

Issued at 400 AM MST Wed Dec 10 2025

The area is currently enjoying a temporary lull in the high wind threat as a surface high settles in over the High Plains. GOES satellite imagery shows the upper level low responsible for yesterday's strong winds continuing to race eastward, now located near the Great Lakes. The next system is already moving into the Pacific northwest, with mid to high level cloud cover apparent streaming out ahead. Initially, the ridge over the southwest CONUS is expected to amplify slightly, which will pushed the stalled mid- level frontal boundary back to the northeast today.

The surface high will also begin to retreat this morning. Pressure falls are expected to begin soon in the immediate lee of the Laramie Range, but will be slow to spread much further east than I-25 today. So, even as cross-barrier height and pressure gradients increase rapidly today, the high wind threat will be more localized to areas along and west of I-25 thanks to the position of the surface trough. Overall gradients are expected to climb rapidly today, peaking in the mid afternoon before leveling off or dropping off slightly overnight and then reaching another, potentially higher peak Thursday morning. Arlington to Bordeaux MSLP gradients reach their first maximum this afternoon at around 6-mb, and then climb to another max at 15z Thursday at nearly 8-mb. Compared to Tuesday's high wind event, 700-mb winds are about 5-8 knots weaker this afternoon through Thursday. Similarly, 700-mb height gradients are approximately 15-m weaker. However, local surface pressure gradients get close (but not quite) to where they were yesterday. Taken all together, this suggest that phase two of the wind event will likely fall slightly short of matching phase one, especially to the same spacial scale. Since we are still likely to observe mountain wave breaking events today and tomorrow, a few isolated observations matching or exceeding Tuesday's top gust of 87 mph cannot be ruled out, but overall expectations are a touch lower for maximum wind gusts today. While high winds will probably be quite consistent in the typical wind prone areas beginning this morning and lasting through Thursday evening, the adjacent zones may also see occasional lulls or breaks in the wind in between mountain waves, especially overnight.

The surface trough will delineate the boundary between a warmer and cooler airmass today as well. Areas that get into the strong westerly winds this afternoon will probably warm at least 5 to 10F above those to the east of the surface trough, where southerly winds will prevail. We will need to watch for a few rain and snow showers this afternoon in our northern and eastern zones, supported by some overrunning warm air advection aloft as the front retreats to the northeast. Expect a very mild night tonight for much of the area as westerly winds keep the boundary layer mixed. This will lead into another mild day Thursday as winds spread further to the east. We'll be looking at widespread upper 50s to 60s for the High Plains, approximately 20F above average for this time of year.

Another surface cold front is expected to approach the area Thursday evening on the leading edge of another high pressure riding down the eastern edge of the Rockies. This will bring another break in the high winds as the pressure gradient reverses across the barrier. We will also need to keep an eye on this for another round of banded precipitation associated with frontogenesis slipping into our area.

LONG TERM /FRIDAY THROUGH TUESDAY/

Issued at 248 AM MST Wed Dec 10 2025

The long term period will be dominated by continued northwest flow aloft. Expect to repeat the last few days once again on Friday, with the ridge amplifying slightly and nudging the stalled boundary off to the east. However, most models indicate that this next surface high pressure will be a bit stronger and more stubborn than the current one, so areas especially along and northeast of the North Platte River Valley may remain quite chilly on Friday and Saturday. There is a bit of uncertainty in where this boundary will set up, which implies quite a bit of uncertainty in high temperature forecasts over the High Plains for both days. These cold arctic air-masses often have more staying power than models indicate initially, so we will need to watch this to potentially bust Friday and Saturday's forecast highs by nearly 20F in the Wheatland to Scottsbluff corridor if the position of the front is off even just slightly. Unfortunately, it does look like the front will retreat just enough to allow for a strong pressure gradient over our wind prone areas once again. It is possible additional High Wind Warnings may be needed as soon as Friday evening. Current probabilities for Friday evening into Saturday morning are about 50 to 80% for the wind prone areas. This event, if realized, would likely be confined to the wind prone areas, and would be characterized as a much more typical high wind event for our area.

Forecast headaches related to the stalled mid-level frontal boundary will finally leave the area towards the end of the weekend. Models are in good agreement showing a broad, strong upper level ridge shifting eastward Sunday into Monday. This will push the baroclinic zone quickly to our east, and usher in a more tranquil weather period. Temperatures are also expected to climb for the entire area during this period as cold air rapidly retreats. NAEFS mean 700-mb temperatures exceed the 99th percentile of climatology by Sunday, cresting around +6C over much of the area! Current forecasts are within a few degrees of daily record highs at Laramie and Cheyenne. Expect little to no chance for precipitation during this period. Slight chances for mountain snow return by Tuesday or Wednesday, but uncertainty is considerable at this lead time.

AVIATION /12Z TAFS THROUGH 12Z THURSDAY/

Issued at 439 AM MST Wed Dec 10 2025

The cold front that swept through last evening will retreat across the High Plains today, turning winds southerly at CYS and Nebraska terminals as it moves out. CYS may see a brief period of low CIGs this morning, but winds will turn westerly by around midday and kick any remaining low CIGs out. Expect strong winds once again at all Wyoming terminals beginning late morning and lasting through the entire TAF period. Look for gusts reaching 40 to 50 knots. There will be temporary breaks or lulls in the strong surface winds, but expect to find significant LLWS during periods when surface winds are light. Nebraska will get a break from the gusty winds today, but expect a few gusty southerlies around 20 to 25 knots.

CYS WATCHES/WARNINGS/ADVISORIES

WY...High Wind Watch from noon MST today through Thursday afternoon for WYZ101. High Wind Warning from 8 AM this morning to 5 PM MST Thursday for WYZ104-109-113-115. High Wind Watch from 8 AM MST this morning through Thursday afternoon for WYZ105. High Wind Warning from 9 AM this morning to midnight MST Thursday night for WYZ106-117. High Wind Warning from noon today to 5 PM MST Thursday for WYZ107-118. High Wind Warning until 5 AM MST Friday for WYZ110-116. Winter Weather Advisory until 11 AM MST this morning for WYZ112-114. NE...None.