High Wind in Wyoming, February 7, 2025

Area Forecast Discussion
National Weather Service Cheyenne WY
439 AM MST Fri Feb 7 2025

.KEY MESSAGES...

- Another wind event is anticipated Friday through Saturday
  morning. High Wind Watches and Warnings are in effect.

- A strong cold front Friday evening will bring accumulating
  snowfall to the mountains along with a line of briefly intense
  snow showers to the adjacent valleys of Carbon and Albany
  counties.

- Active long term pattern with several shortwaves pushing through
  the region with arctic air returning behind them.

&&

.SHORT TERM /THROUGH SATURDAY/...
Issued at 430 AM MST Fri Feb 7 2025

Active weather returns today as an incoming trough fuels another
round of winds and wintry precipitation across the region,
though uncertainty remains for several of our zones and if they
will hit high wind warning criteria for the day, but nonetheless
breezy to gusty conditions will exist for our usual wind prone
locations across southeastern Wyoming with light to moderate
snowfall moving into our Snowy and Sierra-Madre ranges as well.

A trough moving across the western US will help to re-ignite the
stalled out boundary just over and just to the south of the
region as of this writing. We'll see this feature lift northward
alongside favorable warm air advection, allowing for notably
warm temperatures for the afternoon across the region despite
the cool start we're seeing to the morning, particularly
here in central and eastern Laramie County where lows are
bottoming out into the teens. The warmest highs for the day
should be most of our locations north and east of the Laramie
Range, with highs in the 40's to 50's, perhaps even peaking
right around 60 degrees in some locations.

Meanwhile further west, winds should begin picking up here in
the next few hours as we once again see another high wind event
for the CWA. This one isn't as cut and dry as previous events
though, and a bit more uncertainty lies outside of our usual
wind prone locations. Of note is the summit of the southern
Laramie Range into the foothills and Cheyenne Ridge. The low
moving across may help to facilitate a few quick gusts into
this afternoon, but the bulk of the strongest winds will be
likely for more northern portions of these zones instead of
across the I-80 corridor. Still, probabilities for winds 41+
knots in the NBM are peaking at 40-70% across this region, and
with the NBM generally on the low side for winds in our region,
it gives good confidence we should see one or two wind gusts
reach high wind criteria, perhaps even as far south as the I-80
corridor. Therefore, have upgraded the watches for these zones
to warnings to account for this. And even our wind prones aren't
exactly a slam dunk this go around either, with in house
guidance only around a 45-55% probability of gusts 60+ mph in
Arlington and Bordeaux. But a 700mb jet of 50-60 knots and the
potential for a few mountain waves should give some confidence
that we'll see the stronger winds in these areas as well.

Finally, precipitation should overspread a majority of the CWA
ahead of the frontal boundary, with the strongest chances for
our Sierra-Madre and Snowy Ranges. Overall QPF generally isn't
very high, and the faster nature of this system will help to
limit accumulations, with around 6-12 inches possible for these
mountains, generally just shy of warning level criteria outside
of the peaks and crests where a few more inches may occur.
Further down into the adjacent slopes and valleys, 0.5-2 inches
may be possible with a locally stronger snow shower or two,
possibly becoming squall worthy under a marginal environment for
development. One saving grace may be the fact that temperatures
have been on the warmer side, but any stronger bands could
produce enough snowfall or be accompanied by stronger winds that
will quickly reduce visibilities and significantly hinder
travel. Timing of the bands would place the highest potential
for Carbon County between 3-7 PM, and Albany County around 5-8
PM.

Moving into Saturday, attention turns to much cooler
temperatures behind the cold front as arctic air descends across
the area. Highs on Saturday are expected to remain just below
30-40 degrees outside of our western mountainous zones, with
overnight lows into Sunday morning into the teens and single
digits, a preemptive sign of the cold to come. Some breezes are
possible once again but not near to the strength we're expecting
for today, and a quick moving burst of light precipitation may
bring a light snow from Cheyenne eastwards into the southeastern
Nebraska Panhandle, but between the speed, low QPF, and lack of
stronger forcing, don't expect anything more than an inch or
less.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
Issued at 430 AM MST Fri Feb 7 2025

Primarily zonal flow expected through the end of the weekend into
early next week as a broad, upper-level trough over Canada and a
broad ridge over the southern CONUS promote funneling of the upper-
level flow across the region. This fairly stagnant flow patterns
remains in place during the day Sunday before a shortwave pushes
through the flow early Monday morning. With dry, westerly flow
aloft, as indicated by the NAEFS mean precipitation water values
around 1.6 sigma below average for this time of year, should keep
any significant precipitation chances out of the region. The higher
terrain could see some light snow or flurries, as upslope flow
develops, but dry air remains in place. With zonal flow throughout
most of the atmosphere on Sunday, a stationary cold front at 700mb
will attempt to meander southward during the day Sunday before being
pushed back towards the north as mild WAA. As a result, daytime
highs on Sunday will be a bit cool, in the upper-20s to mid-30s area-
wide. The surface cold front will be slightly further south than the
700mb cold front, resulting in the fairly chilly temperatures on
Sunday. Luckily, no major height gradients at 700mb and not overly
strong pressure gradients at the surface will lead to fairly calm
winds throughout the day Sunday. However, overnight lows are
expected to tank into the single digits low teens Sunday night into
Monday morning, so the slight breezy will make it feel closer to the
single digits to below zero in many locations.

The first of two upper-level shortwaves will push into the region
throughout the day Monday. This shortwave does look to be the weaker
of the two shortwaves expected to impact the region, but could still
give the CWA a chance at some decent snowfall. Several lobes of
500mb vorticity will push through, leading to modest synoptic lift
due to cyclonic vorticity advection. Further down at 700mb, the
shortwave is not expected to impact height gradients much to at all,
leading to fairly calm winds once again Monday morning. As the day
progresses a surface high pressure system will ride the broad 700mb
trough to the north of the CWA in eastern Montana and the western
Dakotas. This will increase pressure gradients across the region,
leading to a reverse pressure gradient, evident by the negative
Craig to Casper height gradients. While the reverse gradient should
not be strong enough to produce high winds, elevated winds
throughout the day cannot be ruled out. This is especially true in
the afternoon and evening hours as an arctic front approaches and
moves through the region, dropping 700mb temperatures into the -17
to -20C range. This cold front will push through the northern zones
fairly early in the day, leading to a sharp temperature gradient
from north to south with the high in Cheyenne at 26F and the high in
Lusk at 11F. As the strong arctic front pushes through the region,
there will be an average amount of moisture present, leading to the
development of widespread snowfall along and behind the front. As a
result, many location could see between a 0.5 and 1 inch of snow
Monday evening into early Tuesday morning. As winds pick up in
association with the arctic front and frigid temperatures move into
the CWA, wind chill values are expected to tank into the negative
teens to negative 20s, leading to the possible need for Extreme Cold
headlines in future forecast updates. As of now, no cold headlines
have been issued as this event is still a few days away and social
media posts have already started spreading the message of very cold
temperatures on their way.

Very cold temperatures remain the primary concern Tuesday and
Wednesday, as arctic air remains over the region and winds continue
to be fairly breezy, especially overnight and into early Wednesday
morning. A reinforcing shot of arctic air is expected to enter the
region early Wednesday morning as the second of two shortwaves
pushes towards the CWA. This shortwave will be the strongest of the
two, as the shortwave deepens into a large, positively tilted
trough. Fairly strong 500mb CVA will be present aloft as this trough
pushes into the Intermountain West, favoring synoptic lift across
the CWA. Moisture values are expected to recover to more seasonable
values just in time for this system, due to the more moist origins
of the trough since it came onshore from the Pacific Ocean. However,
moisture values will still remain about 1.0 sigma below
climatological average, decreasing the amount of snow accumulation
expected with this system. One thing is fairly confident with this
system and that is the reinforcing arctic air leading to Wednesday
morning lows in the negatives for almost the entire CWA. With fairly
breezy conditions due to the reinforcing cold air, wind chills
values will once again tank towards the -20 to -25F mark, continuing
the concerns for Extreme Cold headlines needed for mid-week. For
now, this system will continued to be monitored with decisions about
Extreme Cold headlines likely in the upcoming forecast package
updates.

&&

.AVIATION /12Z TAFS THROUGH 12Z SATURDAY/...
Issued at 430 AM MST Fri Feb 7 2025

Fairly complex forecast across southeast Wyoming and western Nebraska
today as a cold front slowly approaches the region and gets hung up
along the Laramie Range. Very strong winds expected along and west
of the Laramie Range with gusts up to 50kts likely at KRWL and gusts
between 35 and 40kts at KCYS and KLAR. Some winds will spill over
into western Nebraska, resulting in gusts between 25 and 30kts at
KSNY. Snow showers will develop later today and move west to east
across southeast Wyoming, with additional snow showers developing
over southern South Dakota and moving north to south across the
Nebraska Panhandle, impacting KCDR and KAIA. Expecting MVFR
conditions at these terminals as snow showers move over them. KLAR
and KRWL may see brief periods of IFR conditions due to very heavy
snow bands and the potential for snow squalls at these two
sites.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...High Wind Warning from 7 AM this morning to 5 AM MST Saturday
     for WYZ104.
     High Wind Warning from 9 AM this morning to 7 AM MST Saturday
     for WYZ106.
     High Wind Watch from 9 AM MST this morning through this
     evening for WYZ107.
     High Wind Warning from 7 AM this morning to 8 PM MST this
     evening for WYZ109-113.
     High Wind Warning from 7 AM this morning to 7 AM MST Saturday
     for WYZ110.
     Winter Weather Advisory from 2 PM this afternoon to 7 AM MST
     Saturday for WYZ112-114.
     High Wind Warning from 8 AM this morning to 8 AM MST Saturday
     for WYZ116-117.
     High Wind Warning from 5 PM this afternoon to 7 AM MST
     Saturday for WYZ118.
NE...None.

&&

SHORT TERM...CG
LONG TERM...AM
AVIATION...AM