High Wind in Wyoming, March 1, 2024

Area Forecast Discussion
National Weather Service Cheyenne WY
1018 PM MST Thu Feb 29 2024

.KEY MESSAGES...

- Periods of strong winds are expected to persist near Arlington
  and adjacent portions of western and northern Carbon County
  through late Friday afternoon, with wind gusts 60 to 70 MPH
  expected. High Wind Warnings are in effect.

- Warm and dry conditions persist through Saturday.

- A strong cold front will bring much colder temperatures and
  increasing chances for snow to western areas late in the
  weekend into early next week. Significant snowfall
  accumulations will be possible in the Snowy and Sierra Madre
  mountains.

&&

.SHORT TERM /THROUGH SATURDAY NIGHT/...
Issued at 130 PM MST Thu Feb 29 2024

The potential for strong winds will remain the primary focus for
the next 12 to 24 hours, mainly over western areas including ARL
as well as adjacent portions of central & northern Carbon County
beginning late this afternoon into this evening. 850/700 mb CAG-
CPR gradients climb to 70/50 meters after 00z, as pressure falls
spread across the western Dakotas ahead of a fast-moving clipper
system tracking across southern Saskatchewan and Manitoba. This,
combined with substantial subsidence associated with a 120+ knot
SW-NE oriented H25 jet & 45 to 55 knot 700-800 millibar flow may
support wind gusts to 60+ MPH near Arlington by late afternoon &
early evening. Wind gusts have already approached 50 MPH through
the early afternoon, and gradients should only strengthen during
the next several hours through early Friday morning. In-house RF
models for Arlington suggest a 60 % probability of exceeding the
58 MPH wind gust warning threshold with multiple parameter space
analogs matching instances of 65-70 MPH gusts. GFS soundings for
Rawlins suggest deep mixing and robust subsidence during the day
on Friday w/ 50+ knots available to mix. Although subsidence and
low-level gradients could be sufficient to trigger 60+ MPH gusts
at some point during the overnight across western Carbon County,
confidence is much higher during the late morning into the early
afternoon hours on Friday. A notable kink in the 500 hpa heights
suggests mountain waves in the vicinity of the Snowy Range which
could keep winds elevated through much of the day on Friday.

Otherwise, a warm and generally dry pattern will prevail through
Saturday w/ broad and flat upper-level ridging in place ahead of
the next significant short wave. H7 temperatures of +2 to +4 deg
C and strong downsloping could contribute to daytime highs 60-70
F across most areas along and east of I-25 on Saturday, prior to
a strong cold frontal passage late Saturday. Snow showers should
increase in coverage late in the period w/ the cold front.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
Issued at 130 PM MST Thu Feb 29 2024

Overall, no major changes to the extended forecast with unsettled
weather through the early portion of forecast period and somewhat
milder weather Tuesday onward. Main forecast concern will focus on
the increased precipitation chances with the potential for a strong
cold front to dig across the zone by the late weekend into the early
portion of the work week. Confidence is not overly high with this
model setup, with the the medium to long range model having
drastically different solutions in the upper level patterns. As it
currently stands, the Euro has begun hinting towards an upper level
low closing off from the main flow as it drifts northward into the
northern CONUS, with quasi-zonal flow developing across the CWA.
Could see some increased westerly flow with shortwave disturbances
riding along the southern fringes of the upper level feature, giving
increased chances for stronger winds for the region. Under this
setup, not as much precipitation is expected with much of the flow
creating a dry downsloping component to the wind and focusing much
of the energy into the mountain zones where orographic lift will aid
in increased precipitation on the western slopes. The GFS has
remained the more aggressive model, resolving the upper level
features to a fairly deep upper level trough digging from the
Pacific Northwest through to the Intermountain West Sunday through
Monday night. Increased precipitation will be more likely under this
setup with upper level support as the 250mb jet has begun shifting
north with each new model run and placing the areas of lift directly
over southeast Wyoming. Regardless, mountains are expected to remain
the most favorable under either setup, with the strong orographic
lift pushing snow totals for the Sierra Madres and the Snowy Range
upwards to just over a foot or two.

A brief break in the weather is expected by midweek, with a weak
upper level ridge moving east across the Intermountain West and High
Plains as early as Tuesday afternoon. Should be a decent warmup
associated with the upper level pattern, with 700mb temperatures
warming a good 10 degrees from the previous days to around -5C
Tuesday into Thursday. Nevertheless, while the precipitation chances
from Tuesday night into Thursday look diminished, gusty to strong
winds will remain a threat throughout the course of the week with
local in-house model guidance picking up on higher probabilities for
40 to 50 mph wind gusts for the wind prone areas along the I-25 and
I-80 corridors. Some uncertainty if those winds will spill eastward
into the lower elevations. But will continue to monitor through the
weekend for any impacts through next week.

&&

.AVIATION /06Z TAFS THROUGH 06Z SATURDAY/...
Issued at 1017 PM MST Thu Feb 29 2024

Gusty winds will persist at KRWL and KLAR overnight. Gusts over 30
kts are possible, with even stronger wind gusts expected into
tomorrow morning. Breezy conditions expected Friday at all
terminals, with gusts over 20 kts. Stronger wind gusts expected at
KLAR and KRWL. Overall, VFR conditions will exist through the TAF
period with mostly clear skies.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...High Wind Warning until 5 PM MST Friday for WYZ104-109.
     High Wind Warning until 5 PM MST Friday for WYZ110.
NE...None.

&&

SHORT TERM...CLH
LONG TERM...MRD
AVIATION...SF