Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 082333
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
433 PM MST Mon Mar 8 2021

.SHORT TERM...(This evening through Tuesday)
Issued at 238 PM MST Mon Mar 8 2021

Afternoon temperatures are currently in the 60s over the Nebraska
Panhandle and 50s across southeast Wyoming as the upper level
cloud cover, that has kept temperatures slightly cooler today,
continues to break up. Gusty winds around 35-45 MPH across much of
Carbon County in Wyoming will continue through the rest of this
afternoon with mountain wave activity evident from latest GOES
imagery. 700mb winds aloft begin to increase this evening over the
Arlington area and continuing towards midnight with 55-60 kts per
the latest GFS. Stronger subsidence over the North Snowy Range
Foothills develops by midnight and will support wind gusts up to
65 MPH. Therefore, decided to upgrade the High Wind Watch to a
Warning beginning 6 PM Monday through 9 AM Tuesday. CAG-CPR
850/700mb HGT gradients all remain below the standard benchmark of
50m, but MSLP gradients across the Snowy Range tighten up around
12z Tuesday which could turn out to be the period of strongest
winds. Additionally, strong subsidence develops over the North
Laramie Range with strong flow at 700mb. Debated about the
potential for strong winds Tuesday morning along I-25 north of
Wheatland, but the subsidence looks to remain pinned to the
immediate downward slopes of the higher terrain. A cold front will
begin to sweep over the CWA late Tuesday morning which diminish
the high wind potential and begin to bring colder air into the
area.

Temperatures may briefly climb into the 50s and low 60s east of the
Laramie Range Tuesday ahead of the front before dropping towards the
20s by Wednesday morning. Shortwave energy looks to eject out from
the large trough digging down the Pacific Coast Tuesday evening
which will support large scale ascent across much of east-central
Wyoming. Isentropic lift centered over a 700mb frontogenetic zone
located across northern Converse County developing Tuesday night
into early Wednesday will support impressive precipitation rates
across the area. Initial precipitation may fall as rain over the
area as temperatures continue to fall, but by midnight snow will be
the primary precipitation type. Current interquartile ranges for
probabilistic snowfall guidance suggests 3 to 8 inches for the
Douglas area with slightly higher amounts towards northwest
Converse County. Highest snowfall rates are expected early
Wednesday morning which could make the morning commute in the area
difficult. With the event onset still over 24 hours away, decided
to leave the Winter Storm Watch in effect for Converse and
Niobrara Counties. As the event gets closer, additional headlines
may be needed for the North Laramie Range and northern Nebraska
Panhandle. Snowfall will dissipate late Wednesday afternoon, but
colder temperatures will remain.

.LONG TERM...(Tuesday night through Monday)
Issued at 238 PM MST Mon Mar 8 2021

Some lull in conditions Weds night into Thursday then attention
focuses on the next system that will drop into the sw CONUS
Thursday then move slowly east and northeast across the Rocky mtns
into the plains over the weekend. Models continue to be
inconsistent so lots of uncertainty remains as to what effects it
will bring here. Potential exists for some good snows given the
slow motion so obviously will keep a close watch on it. Otherwise
colder air will settle in over the area and hold through the
weekend with broad upper cyclonic flow developing over much of
North America by Monday.

&&

.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 430 PM MST Mon Mar 8 2021

VFR. Wind gusts to 37 knots at Rawlins and Laramie until 04Z,
then to 28 knots at Rawlins after 06Z, and to 25 knots at all
other terminals after 15Z Tuesday. Low level wind shear at Rawlins
from 02Z to 06Z, and at Laramie from 04Z to 15Z.

&&

.FIRE WEATHER...
Issued at 143 AM MST Mon Mar 8 2021

Before the frontal passage Tuesday evening/night, fire weather is
still of some concern for portions of southeast Wyoming and the
Nebraska panhandle as the humidities will be very low and winds
will pick up a little Monday into Tuesday from a brief frontal
passage before the main one. As of right now, nowhere will reach
critical conditions, but it will get close Monday and Tuesday
during the day! Once the front passes through Tuesday
evening/night, humidities increase and most of southeast Wyoming
and the Nebraska panhandle will receive precipitation. After that,
another low pressure system is expected to pass through Friday
night into Sunday bringing more precipitation and higher
humidities.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...High Wind Warning until 9 AM MST Tuesday for WYZ110.

     Winter Storm Watch from Tuesday evening through Wednesday
     afternoon for WYZ101-102.

NE...None.
&&

$$

SHORT TERM...MB
LONG TERM...RE
AVIATION...RUBIN
FIRE WEATHER...LK



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