261
FXUS65 KCYS 300905
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
305 AM MDT Tue Apr 30 2024

.KEY MESSAGES...

- Strong winds likely with and behind the front across the
  Laramie Range Tuesday morning. Gusts up to 60 mph possible.

- A series of weather disturbances will move across the
  forecast area Thursday and Friday, producing a chance of
  showers and thunderstorms mainly during the afternoons and
  evenings.

- Drier and warmer conditions are anticipated for the weekend.

&&

.SHORT TERM /THROUGH WEDNESDAY NIGHT/...
Issued at 305 AM MDT Tue Apr 30 2024

Current KCYS radar loop early this morning shows a solid band of
rain/snow showers (mostly snow above 7000 feet) moving eastward
across southeast Wyoming with webcams showing moderate snow
bands at times west of Laramie. Thankfully, this band is pretty
brief with conditions already improving in Rawlins where the
precip has switched back to rain at 300 am local time. Although
some of the lower elevations near Arlington and Elk Mountain may
see up to 2 inches of snow, with 3 to 6 inches for the
mountains, will not issue any winter weather headlines since
most of the snow is briefly sticking on area roadways and then
melting due to the higher pavement temperatures. Some travel
impacts are expected over the next few hours between Rawlins and
Laramie before conditions improve quickly around sunrise.

Otherwise, the only other forecast concern today relates to
strong gusty winds. In terms of fire weather, cancelled the Fire
Weather Watch for far eastern Wyoming and most of the Nebraska
Panhandle due to recent damp conditions and wetting rainfall
this past weekend...in addition to another solid band of
rainfall moving into the area early this morning. Expect another
wetting rain along and north of highway 26 and 92 with KCYS
radar showing this band intensifying just west of the
Nebraska/Wyoming border. Although winds will increase with lower
humidities by this afternoon, do not expect widespread
hazardous fire weather conditions due to recent precipitation
and developing green-up. Further west, kept the High Wind
Warnings going today even though models have backed off a bit on
the highest wind speeds. Models still show 40 to 50 knots of
700mb flow with very good low level subsidence. Winds have
struggled to increase thus far with only a few gusts around 40
to 45 mph observed...even across the wind prone areas. Expect
this to change over the next 3 to 6 hours, but winds may
struggle to reach criteria with such a short window in this
event. Also, kept the High Wind Watch for central Laramie County
including Cheyenne. Not confident enough to upgrade to a
warning this morning, but not completely convinced that wind
gusts won`t approach 55 MPH either. Gusty winds should diminish
this evening around sunset. High temperatures today will likely
occur late this morning, with temperatures falling into the 50s
mid to late afternoon behind the cold front. Most of the
precipitation associated with this first cold front should end
by this afternoon.

Models show the next Pacific cold front and associated upper
level trough moving east of the Great Basin Region tonight and
into early Wednesday. A few days ago, some models were much more
aggressive with this system and showed widespread snow across
much of southeast Wyoming. Models have trended much weaker with
this system and continue to show the more progressive solution.
Therefore, expect limited impacts Wednesday and Wednesday night.
All models show the leading edge of the cold front moving into
the area Wednesday afternoon with numerous rain showers and
widely scattered thunderstorms developing along it. Kept POP
between 40 to 70 percent on Wednesday with slightly cooler
temperatures compared to this afternoon. The upper level trough
axis will quickly move into Wyoming Wednesday evening, with
snowlevels lowering to 5000 feet. Thankfully, once the coldest
air gets here most of the precipitation should be ending. Expect
any snow accumulations to be minimal with local accumulations up
to one inch on grassy and elevated surfaces in southeast
Wyoming. The higher mountains may see 2 to 5 inches of snow will
this second round, so winter weather headlines are not expected
at this time. 700mb temperatures will quickly drop between -7c
to -10c Wednesday night, so low temperatures will be quite
chilly for this time of the year and generally in the 20s to
low 30s by early Thursday morning.

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
Issued at 205 AM MDT Tue Apr 30 2024

Thursday...The progressive shortwave trough aloft and its associated
cold front sweep eastward across our forecast area early in the day,
with widely scattered showers along and near the cold front.
Slightly cooler in the wake of the cold front.

Friday...A secondary shortwave trough aloft is progged to move
across our counties near peak heating, and with adequate low and mid
level moisture and a cold frontal passage, we anticipate scattered
showers and some thunderstorms in the afternoon and evening.

Saturday...Warming and drying expected as a transitory low amplitude
shortwave ridge aloft builds overhead.

Sunday...Continued dry as the flow aloft transitions to southwest
and there is limited low and mid level moisture. This day looks like
the warmest day of the period as a low level thermal ridge develops
with 700 mb temperatures near 11 Celsius yielding maximum
temperatures mainly in the 70s.

Monday...Slightly cooler temperatures expected as the next
progressive shortwave trough aloft moves across the region, with the
bulk of the energy projected to remain to our south across Colorado.
However, it looks like there will be adequate low and mid level
moisture to produce isolated to widely scattered afternoon
showers.

&&

.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 1141 PM MDT Mon Apr 29 2024

A weather disturbance and cold front will sweep across the
terminals early this morning, ushering in scattered showers and
some lower ceilings until mid morning today.

Wyoming TAFS...At Rawlins, occasional showers and fog will occur
until 10Z, reducing visibilities to 3 miles and ceilings to
1500 feet. From 10Z to 14Z, ceilings will be near 6000 feet,
then clear skies will prevail. Winds will gust to 35 knots.

At Laramie and Cheyenne, ceilings from 8000 to 12000 feet will
occur until 13Z, with occasional showers at Laramie and ceilings
near 3000 feet until 11Z, then skies will become clear at the
terminals after 14Z. Winds will gust to 45 knots after 10Z.

Nebraska TAFS...Ceilings will range from 8000 to 15000 feet
until 14Z, with occasional showers, then skies will become clear
after 14Z. Winds will gust to 40 knots after 09Z.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...

WY...High Wind Warning from 6 AM this morning to 6 PM MDT this
     evening for WYZ106-107-116-117.
     High Wind Warning until 6 PM MDT this evening for WYZ110.
     High Wind Watch from 9 AM MDT this morning through this
     afternoon for WYZ118.

NE...None.

&&

$$

SHORT TERM...TJT
LONG TERM...RUBIN
AVIATION...RUBIN