Snow Squall Warning 17, NWS Cheyenne, WY

Area Forecast Discussion
National Weather Service Cheyenne WY
455 AM MST Mon Feb 24 2020

.SHORT TERM...(Today through Tuesday night)
Issued at 410 AM MST Mon Feb 24 2020

Increasing and lowering clouds form the west as of 4 AM this
morning, with snow having already begun over the Sierra Madre and
Snowy Ranges and noted across the lower elevations of Carbon
County. Wind shave also increased with this incoming strong
system, with gusts 30 to 40 mph noted between Cheyenne and Rawlins
along the I-80 corridor and gusts to 66 mph already verifying the
High Wind Warning in the Snowy Foothills.

The first of two strong cold frontal passages expected with this
system is about to roll quickly through the region from the west,
just now entering Carbon and Converse Counties, reaching the
Nebraska- Wyoming border around mid-morning, and finally pushing
east of the western Nebraska Panhandle by mid-afternoon. Along
with this front will come a combination of winds and snow showers,
some heavy at times, especially across the mountains and the Pine
Ridge. The front will create an area of surface convergence and
heightened dynamic energy and uplift that will aid in the
production of snow and wind. This combination of features, aided
by dynamics aloft, will lead to hazardous weather conditions for
which a number of warnings and advisories have been issued. Please
see the individual texts for further details, this includes the
High Wind Warnings for six separate zones and Winter Weather
Advisories for the mountain zones and the counties included along
the Pine Ridge.

Strong areas of subsidence and increased surface gradients have
already lead to strong gusts to 66 mph across the wind-prone areas
of southeast Wyoming. East Platte County and central Laramie
County have been included in the High Wind Warning due to
guidance indicating that a mountain wave is likely to spill over
the Laramie Range and into the PLains. The mountain wave will
likely pair with the strong cold front for a prolonged period of
gusty winds today.

Also of note is the possibility for snow squalls today associated
with the front and the strong dynamic forcing aloft. Please be
aware of your surroundings today if traveling, especially across
Carbon County, the I-80 Summit, and along or near the Pine Ridge.

Will see a brief lull in winds and snow tonight before a the
second shortwave associated with the closed low system makes its
way from the northwest to southeast, mainly affecting the High
Plains. The associated surface cold front will begin to pass
through around midnight from the north bringing another bout of
snow and strong winds to the Pine Ridge and area mountains through
the late morning. At this point, the Cheyenne Ridge will pick up
two to three inches as well, doing well in a northerly pattern.
Winds won't quite be as strong overall so no HIgh Wind Warnings
have been issued at this time for Tuesday, however, there are
signals of a short burst of wind to the east of the south Laramie
Range early Tuesday morning as a mountain wave spills over into
the Plains, and will have to continue to monitor this possibility.

Have gone ahead and increased the overall snow totals across the
region with the increased instability, upper level dynamics and
guidance liquid amounts. Think precipitation will generally fall
as snow as the warmer periods of the day today show only isolated
showers, and elsewhere, temperatures will either be below freezing
or will wet-bulb down to zero.

Besides widespread blowing snow across the region and gusty winds,
please note that wind chill temperatures will also be quite low,
overnight tonight varying from the single digits in the east, to
10 below to the west. 20 below zero will be noted across the Snowy
and Sierra Madre Ranges.

By Tuesday evening, the backside of this dynamic and energetic
system will have passed through, winds will diminish and show
showers will tapper off. Expect a quiet and chilly TUesday night.

.LONG TERM...(Wednesday through Sunday)
Issued at 158 PM MST Sun Feb 23 2020

A chilly morning across the CWA Wednesday in the wake of the low
pressure system with mins in the single digits to lower teens.
Still on the cool side Weds and Thursday then warming to close
out the week. Mainly dry but another fast-moving shortwave should
bring some snow showers to mainly the mtns on Thursday but amounts
not a lot given the speed of the system. Breezy conditions with
the shortwave Thursday otherwise winds not looking too significant
through the period as well.

&&

.AVIATION...(For the 06Z TAFS through late Monday evening)
Issued at 1045 PM MST Sun Feb 23 2020

Next Pacific storm system and associated cold front will move across
the southeast Wyoming terminals between 08z and 13z Monday morning,
and then between 12z to 16z across western Nebraska with winds
shifting into the north or northwest. Snow showers are expected to
develop as the front slides southeast, impacting most terminals
through the day on Monday and possibly Monday night.

HAZARDS/WEATHER TRENDS: LLWS is the initial Aviation threat late
tonight as winds sharply increase out of the west or northwest near
the surface cold front. Moderate to strong turbulence expected after
07z once the cold front moves into the area. SNOW will begin once
the LLWS threat diminishes after 10z. VFR conditions until 10z, then
a brief period of IFR CIGS/VIS for KRWL and KLAR until the band of
snow pushes east into the high plains. Low confidence on how this
band will impact KCYS and KBFF with downslope winds, so kept VCSH
for those locations.  KCDR and KAIA are looking more likely to be
impacted by IFR conditions as early as 15z-18z Monday. Precip type
is uncertain at this time, but will likely fall as a mix of rain and
snow initially.

&&

.FIRE WEATHER...
Issued at 410 AM MST Mon Feb 24 2020

Low fire weather concerns for the near future as cold
temperatures, snow and blowing snow move into the High Plains and
adjacent HIgh Terrain today and tomorrow. Warming trend will
follow beginning Wednesday with a ridge of high pressure moving in
Friday.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...Winter Weather Advisory until 8 PM MST Tuesday for WYZ101>103-
     112-114.

     High Wind Warning until 5 PM MST this afternoon for WYZ106-107-
     110-116>118.

NE...Winter Weather Advisory until 8 PM MST Tuesday for NEZ002-095.

&&

SHORT TERM...AB
LONG TERM...RE/REC
AVIATION...TT
FIRE WEATHER...AB

Hazardous Weather Outlook
National Weather Service Cheyenne WY
504 AM MST Mon Feb 24 2020

WYZ106-107-110-116>118-251215-
Central Laramie Range and Southwest Platte County-
East Platte County-North Snowy Range Foothills-
South Laramie Range-South Laramie Range Foothills-
Central Laramie County-
504 AM MST Mon Feb 24 2020

This hazardous weather outlook is for portions of south central
Wyoming and southeast Wyoming.

.DAY ONE...TODAY AND TONIGHT

A High Wind Warning is in effect through 5 PM. West winds of 35
to 45 mph with gusts 60 to 70 mph are likely. See Warning text
for further details. Snow showers will combine with winds today
for blowing snow and reduced visibility at times.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

Tuesday will be quite windy and cold with scattered to numerous
snow showers. Blowing snow and reduced visibilities will create
hazardous travel conditions at times.

.Spotter information statement...

Spotter activation will not be needed.

NEZ003-019>021-054-055-096-WYZ104-105-108-109-111-113-115-119-
251215-
Box Butte-Scotts Bluff-Banner-Morrill-Kimball-Cheyenne-
South Sioux-Ferris/Seminoe/Shirley Mountains-Shirley Basin-
Goshen County-Central Carbon County-Southwest Carbon County-
Upper North Platte River Basin-Laramie Valley-East Laramie County-
504 AM MST Mon Feb 24 2020

This hazardous weather outlook is for portions of western
Nebraska...south central Wyoming and southeast Wyoming.

.DAY ONE...TODAY AND TUESDAY

Today and Tuesday will be quite windy with gusts to 50 mph at
times and cold with scattered to numerous snow showers.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH SUNDAY

No hazardous weather conditions expected.

.Spotter information statement...

Spotter activation will not be needed.

NEZ002-095-WYZ101>103-112-114-251215-
Dawes-North Sioux-Converse County Lower Elevations-
Niobrara County-North Laramie Range-Sierra Madre Range-
Snowy Range-
504 AM MST Mon Feb 24 2020

This hazardous weather outlook is for portions of western
Nebraska...east central Wyoming...south central Wyoming and
southeast Wyoming.

.DAY ONE...TODAY AND TUESDAY

A Winter Weather Advisory has been issued as strong winds combine
with scattered to numerous snow showers to produce blowing snow
and areas of reduced visibilities. Travel will become difficult
and outdoor recreation could be life threatening to those not
prepared for severe winter conditions. Additionally, wind chill
temperatures will drop to 20 below zero in the Sierra Madre and
Snowy Mountains leading to frostbite and hypothermia. Please see
text for further details.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH SUNDAY

No hazardous weather conditions expected.

.Spotter information statement...

Please call in or chat us on social media with snow measurements
as accumulation occurs.

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHEYENNE WY
716 AM MST MON FEB 24 2020

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0706 AM     NON-TSTM WND GST 2 NE RAWLINS            41.81N 107.20W
02/24/2020  M60 MPH          CARBON             WY   ASOS

&&

CW

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