A surface trough in lee of the Laramie Range created a strong surface gradient, leading to localized high winds around the Arlington area.
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The episode as NWS CYS wrote it up.
A surface trough in lee of the Laramie Range created a strong surface gradient, leading to localized high winds around the Arlington area.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Cheyenne, WY wrote its last area forecast discussion before the first event at Apr 13, 4:25 AM MST, 3 hours 51 minutes earlier. Its key messages:
Area Forecast Discussion
National Weather Service Cheyenne WY
525 AM MDT Mon Apr 13 2026
.KEY MESSAGES...
- Red Flag Warnings continue for areas east of the Laramie Range
through this afternoon due to gusty winds and dry conditions.
- High Wind Watches remain in effect for the Arlington area and
South Laramie Range into this afternoon.
- Precipitation chances increase Tuesday through the end of the
week with the threat of thunderstorms and snow.
&&
.SHORT TERM /THROUGH TUESDAY NIGHT/...
Issued at 202 AM MDT Mon Apr 13 2026
Enjoy those mostly sunny skies and above normal temperatures for the
daytime hours today because changes are in store Monday night into
Tuesday, more on that in a bit. Rinse and repeat, fire weather
concerns continue into this afternoon as conditions remain very dry
along with gusty winds. A shortwave that slid across the CWA tonight
may kick start high winds over the next several hours and persist
through 3pm this afternoon for the Arlington and South Laramie Range
zones. Dynamics are meager at best, but there is enough of a signal
to keep the High Wind Watch out that was issued yesterday for said
zones. Winds at 700mb ramp up to around 50 knots through the morning
hours, and with enough subsidence aloft, per GFS, these winds may
mix down to the surface. In-house guidance indicates a 60 percent
chance of high winds, with the peak of high winds later this morning
for the areas of concern, mentioned earlier, along I-80.
Switching gears to the ongoing fire weather concerns. Southwest flow
aloft and a lee-side trough, east of the Laramie Range, will keep
winds gusty into the Nebraska Panhandle. This along with an
abundance of dry fuels has influenced the SPC to introduce an area
of critical fire weather concerns across eastern Wyoming into the
Nebraska Panhandle through this afternoon. This area aligns nicely
where west to southwest winds 15 to 20 mph, gusting up to 35 mph,
will occur along with min RH values dipping down to 8-12 percent.
Therefore, the Red Flag Warning that is out will continue through
8pm this afternoon. Locations west of the Laramie Range will escape
the fire weather threat as isolated showers are possible for most of
today, which is depicted nicely by hi-res guidance. Another
shortwave will rotate in over western portions of the CWA, this will
keep chances of showers in the forecast, snow at higher elevation
(above 7K feet), Monday night through Tuesday.
Speaking of Tuesday, a 500mb trough and vort max will slide in
and cross the region through the day, this will spread
precipitation chances east into the lower elevations,
encompassing most of the CWA. This shows up nicely on the hi-res
model suite, with precipitation chances along the I-80 corridor
initially and spreading east/northeastward throughout the day.
Ensembles show at least a 60 percent chance of a tenth of
liquid, which will be a welcomed sign as our CWA has been
extremely dry this season. Just like with the precipitation
Monday night, the higher terrain may see a few inches of late
season snow, not reaching advisory criteria at the moment.
Temperatures will be a tad cooler with highs in the 50s west of
I-25 and mid 50s/60s east of the corridor. Regarding winds, what
winds you'll be saying, as winds for Tuesday/Tuesday night will
remain relatively calm.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
Issued at 222 PM MDT Sun Apr 12 2026
The period begins with a departing shortwave trough and building of
a weak mid-level ridge downstream of a more amplified trough, which
will be the culprit of more active weather later in the week and
into the weekend. As a result, mild temperatures will remain in
place on both Wednesday and Thursday, followed by an increase
in our winds as quasi-zonal 700 mb flow ramps up to 35-40 knots.
In-house guidance has 30-40% probabilities of high wind
conditions for the usual wind-prone areas starting Wednesday
morning before tapering off Thursday night into Friday. While
not as impressive as what we have seen in recent, previous
events, omega fields continue to show a mountain wave pattern
across the Snowy and Laramie Ranges, so will see an increase in
our winds during this time at the very least. Ensemble guidance
suggests that temperatures will peak in the low to mid-50s west
of the Laramie Range, and in the 60s to perhaps 70 degrees east
of the I-25 corridor. Thursday is forecast to be our warmest day
of the period under warm advection ahead of an advancing cold
front that will move across Southern Wyoming and Western
Nebraska overnight Thursday into Friday. However if the front
and associated surface low trends more progressive, we likely
won't warm up as much on Thursday as ensembles are currently
showing, as much of our Nebraska counties are showing 50th
percentile maximum temperatures in the mid 70s.
Friday will feature much cooler temperatures behind the front, with
temperatures dropping a good 20-25 degrees relative to Thursday
given strong low-level cold air advection in combination with
blustery NNW surface flow. As for any beneficial moisture...don't
get your hopes up. Current LREF PWAT percentiles are at or below the
50th percentile for Southeastern Wyoming and Western Nebraska
through Friday with ensemble mean QPF at or less than 0.1". The only
exception are the Snowy and Sierra Madre Ranges where probabilities
of exceeding 0.2" of QPF through Saturday afternoon look to be about
60%. Saturday will again feature below-average temperatures
primarily in the 30s and 40s which is running around 15-20 degrees
below climatological values. Expect temperatures on Sunday to
rebound nicely to at or slightly above seasonal values as a weak mid-
level ridge will build in from the west. Dry conditions are expected
at this time.
&&
.AVIATION /12Z TAFS THROUGH 12Z TUESDAY/...
Issued at 525 AM MDT Mon Apr 13 2026
VFR conditions will prevail across all terminals for the duration of
this TAF period. Winds will ramp up and become west/southwesterly
around 12Z for all sites, with gusts in the range of 30 to 40 knots,
possibly higher at times for KRWL and KLAR. Winds will diminish
between 00Z and 03Z. Low end precipitation chances at the tail end
of this forecast, kept it out of the TAFs due to low confidence.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...Red Flag Warning until 8 PM MDT this evening for WYZ417>419-
430>433.
High Wind Watch until 3 PM MDT this afternoon for WYZ110-116.
NE...Red Flag Warning until 8 PM MDT this evening for NEZ434>437.
&&
SHORT TERM...RZ
LONG TERM...NB
AVIATION...RZHazardous Weather Outlook National Weather Service Cheyenne WY 202 AM MDT Mon Apr 13 2026 NEZ002-003-019>021-054-055-095-096-WYZ101>119-140815- Dawes County-Box Butte County-Scotts Bluff County-Banner County- Morrill County-Kimball County-Cheyenne County- Northern Sioux County-Southern Sioux County- Converse County Lower Elevations-Niobrara County- North Laramie Range-Ferris/Seminoe/Shirley Mountains- Shirley Basin-Central Laramie Range and Southwest Platte County- East Platte County-Goshen County-Central Carbon County- North Snowy Range Foothills-Southwest Carbon County- Sierra Madre Range-Upper North Platte River Basin-Snowy Range- Laramie Valley-South Laramie Range-South Laramie Range Foothills- Central Laramie County-East Laramie County- 202 AM MDT Mon Apr 13 2026 This hazardous weather outlook is for portions of panhandle Nebraska...east central Wyoming...south central Wyoming and southeast Wyoming. .DAY ONE...TODAY AND TONIGHT - Red Flag Warnings continue for areas east of the Laramie Range through this afternoon due to gusty winds and dry conditions. - High Wind Watches remain in effect for the Arlington area and South Laramie Range into this afternoon. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY - Precipitation chances increase Tuesday through the end of the week with the threat of thunderstorms and snow. .Spotter information statement... Spotter activation will not be needed.
The national radar mosaic for the moment the first event began.
1 high wind. Local standard time, as filed.
Frequent gust of 55 to 60 MPH were recorded along Interstate 80 from WYDOT sensors. A maximum gust of 65 MPH from a WYDOT sensor at Arlington was recorded at 9:16 AM MDT on 4/13.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wyoming in 2026Every state in 2026This day in weather historyWarnings in Wyoming, April 2026
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 1324153.