High Wind in Wyoming, May 19, 2022

Area Forecast Discussion
National Weather Service Cheyenne WY
447 AM MDT Thu May 19 2022

.SHORT TERM... (Today through Friday night)
Issued at 400 AM MDT Thu May 19

KEY MESSAGES:

1) High Wind Warnings in effect to start the day with wind gusts 50
to 60 mph likely along and west of the Laramie Range through Friday
afternoon.

2) Winter Weather Headlines have been issued for a strong cold front
that is still forecast to move through quickly Thursday night,
dropping our temperatures rapidly with prolonged precipitation
behind it. The precipitation will still begin as rain, transitioning
to snow between 10 PM MDT Thursday and 6 AM MDT Friday for southeast
Wyoming. Forecast snow totals have increased since the previous
shift with the Snowy and Sierra Madre Ranges receiving 8 to 13
inches, the South Laramie Range 7 to 13 inches, and the Cheyenne
Ridge up to 4 to 8 inches. For the Nebraska panhandle, it will be
primarily rain through the event, but Kimball county could see 3+
inches of snow between 6 PM MDT Friday and 12 PM MDT Saturday.

3) Forecast temperatures Friday night through Saturday morning have
dropped significantly since the previous shift, therefore we have
issued a Hard Freeze Watch for southeast Wyoming and portions of the
Nebraska panhandle.

Discussion: High Wind Warnings remain in effect for likely 50 to 60
mph wind gusts in the wind-prone areas of southeast Wyoming. Winds
will likely begin to die off once the front pushes through and
breaks down the mountain wave and switches the wind direction to
northerly.

There have been some significant changes to the overall
forecast since the previous shift due to the front pushing all the
way through our CWA, then holding in Colorado, keeping Wyoming
especially in the very cold sector of the front. In addition, models
are showing a secondary low developing through the day Friday in
Colorado, switching the wind direction to more of a northeast flow
at the surface, providing upslope flow especially along the Cheyenne
Ridge and portions of the southern Nebraska panhandle that are
already very moist from previous precipitation. All of these factors
combined have resulted in increased snowfall totals, especially in
the south Laramie Range and Cheyenne Ridge. Due to this being a late
season event, there is uncertainty as to the transition time from
rain to snow, however we can say, once the rain transitions to snow,
it will remain snow through the rest of the event. At the beginning
of the event, there will likely be little to no accumulation,
however as snow continues the grassy and elevated surfaces will see
some accumulation. Then, potentially in areas receiving a
significant amount of snow, accumulation may be seen everywhere.

Another result of the cold front dropping further south than what
has been previously forecast is an extended period of near to below
freezing temperatures beginning tonight. For this reason, we have
issued a Hard Freeze Watch for Friday night when low temperatures
are forecast to be 22 to 32 degrees across southeast Wyoming and the
Nebraska panhandle. The confidence is moderate for this hard freeze
with the only uncertainty coming from the cloud cover that is
expected to persist until Saturday afternoon. Once skies clear,
especially in areas that have received accumulating snowfall, due to
radiative cooling, the temperatures will plummet overnight
Saturday.

.LONG TERM...(Saturday through Wednesday)
Issued at 343 AM MDT Thu May 19 2022

(Long Term Update): With the major shift in the short term forecast
now depicting more impactful winter storm and prolonged cold
overnight temperatures, the long term discussion (See discussion
below) will continue to be the valid long term discussion as we
work on getting out key messaging for the incoming storm. The only
change made to the long term forecast was to adjust minimum
temperatures on Saturday much colder than the previous forecast.

Key Impact Messages:

1) Likely lingering travel and winter impacts ongoing beginning of
Saturday as snow slowly ends by the afternoon across far south WY/Ne
Panhandle to the CO border. Below normal temperatures expected with
below freezing temperatures. Sensitive vegetation could be
vulnerable.

2) Another snow/rain mix with possibly a few rumbles of thunder
looking probable late Sunday into Monday. Snow west at the I-80
Summit west of the Laramie Range early then transitioning to rain
through the day with a few thunderstorms across the High Plains.
Rest of the week should be drier and slow warm trend.

Weather Details: Longwave trough stretching from the Great Lakes to
the Pacific Northwest with colder Canadian airmass will aid
lingering snow showers across far south WY and Nebraska Panhandle
Saturday morning to the afternoon. Likely residual travel and winter
impacts ongoing at this time from the previous higher snowfall rates
on Friday into early Saturday. Please plan accordingly if travel is
planned at this time.

Surface high pressure over the Dakotas and another shortwave trough
shifting through the main jet stream flow will keep colder air over
the region this upcoming weekend. Much below normal temperatures are
expected with freezing low temperatures. Plan accordingly for any
outdoor vegetation that could be sensitive to the cold. Did add
patch frost for Sunday morning for areas outside of snow areas from
the previous day. H7 temperatures will be -12C to -10C this weekend
then warm back to near 0C early next week. Another round of
precipitation is likely late Sunday into Monday with snow west of
the Laramie Range into early Monday morning with precipitation
transitioning to cold rain through the day. Weak instability could
be present across the High Plains for some thunder/lightning but not
expected to be strong/severe at this time given the colder
temperature profiles. Precipitation will draw to a close late Monday
with a more tranquil and slow warming trend through next week under
NW flow from a slowly advancing H5 ridge.

&&

.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
Issued at 343 AM MDT Thu May 19 2022

VFR conditions expected to persist with very gusty winds this
afternoon until a cold front pushes through the area this evening.
Cigs will begin to lower this evening, potentially reaching MVFR
to IFR levels after midnight depending on where the snow sets up.
Showers will begin to pop up around KRWL after 6 PM MDT, then
spread to KLAR between 9 PM MDT and 11 PM MDT. Rain will likely
transition to snow after midnight.

&&

.FIRE WEATHER...
Issued at 343 AM MDT Thu May 19 2022

Warm temperatures and very gusty winds expected ahead of a strong
cold front set to impact southeast Wyoming and the Nebraska
panhandle between tonight and Saturday morning. Little to no fire
weather concerns due to cooler temperatures and increased
moisture and precipitation over the next few days.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...Hard Freeze Watch from Friday evening through Saturday morning
     for WYZ101-102-104>111-113-115>119.

     Winter Weather Advisory from midnight tonight to noon MDT
     Saturday for WYZ110-112-115.

     High Wind Warning until 3 PM MDT this afternoon for WYZ106-110-
     116-117.

     Winter Storm Warning from midnight tonight to noon MDT Saturday
     for WYZ114-116-117.

     Winter Storm Watch from Friday morning through Saturday morning
     for WYZ118-119.

NE...Hard Freeze Watch from Friday evening through Saturday morning
     for NEZ002-054-095.

     Winter Weather Advisory from 6 PM Friday to noon MDT Saturday
     for NEZ054.

&&

SHORT TERM...LK
LONG TERM...AW
AVIATION...LK
FIRE WEATHER...LK

Hazardous Weather Outlook
National Weather Service Cheyenne WY
249 PM MDT Wed May 18 2022

NEZ002-003-019>021-054-055-095-096-WYZ101>105-107>109-111-113-115-
118-119-192100-
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-East Platte County-Goshen County-
Central Carbon County-Southwest Carbon County-
Upper North Platte River Basin-Laramie Valley-
Central Laramie County-East Laramie County-
249 PM MDT Wed May 18 2022

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

.DAY ONE...THIS AFTERNOON AND TONIGHT

No hazardous weather is expected at this time.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

Strong and gusty winds are expected during the day Thursday ahead
of an approaching cold front. Rain will likely transition to snow
for most places Thursday night. Accumulating snow is possible
Thursday night through early Saturday morning. Much cooler
temperatures are expected Friday and Saturday.

.Spotter information statement...

Spotter activation is not needed at this time.

WYZ106-110-116-117-192100-
Central Laramie Range and Southwest Platte County-
North Snowy Range Foothills-South Laramie Range-
South Laramie Range Foothills-
249 PM MDT Wed May 18 2022

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

.DAY ONE...THIS AFTERNOON AND TONIGHT

No hazardous weather is expected at this time.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

High winds are likely early Thursday morning through the afternoon
hours. Winds could gust up to 60 mph. Please refer to the High
Wind Warnings for more details. Rain will transition to snow Thursday
night. Accumulating snow is possible Thursday night through early
Saturday morning. Please refer to the Winter Storm Watches for
more details. Much cooler temperatures are expected Friday and
Saturday.

.Spotter information statement...

Spotter activation is not needed at this time.

WYZ112-114-192100-
Sierra Madre Range-Snowy Range-
249 PM MDT Wed May 18 2022

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

.DAY ONE...THIS AFTERNOON AND TONIGHT

No hazardous weather is expected at this time.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

Strong and gusty winds are expected during the day Thursday ahead
of an approaching cold front. Accumulating snow is likely Thursday
night through early Saturday morning. Snow accumulations of 6 to
12 inches is possible. Please refer to the Winter Storm Watches
and Winter Weather Advisory for more details. Much cooler
temperatures are expected Friday and Saturday.

.Spotter information statement...

Spotter activation is not needed at this time.