-- Discussion containing changed information from previous version are highlighted. --
885
FXUS65 KCYS 301659
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
1059 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.

&&

.UPDATE...
-- Changed Discussion --
Issued at 910 AM MDT Tue Apr 30 2024

Wind gusts exceeding 50 knots have been reported at Cheyenne
Airport as well as in locations along and north of town on I-25.
Therefore the High Wind Watch has been upgraded to a High Wind
Warning for the central Laramie County area through 0z.
Previous High Wind Warnings remain in effect through 0z.
-- End Changed Discussion --

&&

.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 /12Z TAFS THROUGH 12Z WEDNESDAY/...
-- Changed Discussion --
Issued at 1059 AM MDT Tue Apr 30 2024

Strong, gusty winds continue this afternoon behind the cold front.
Gusts over 40 kts can be expected at most terminals. Winds will
begin to ease late this afternoon, with gusts finally dying off this
evening. Overnight, winds may become light and variable. Another
disturbance will move across the area, leading to the potential for
scattered light showers.
-- End Changed Discussion --

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...High Wind Warning until 6 PM MDT this evening for WYZ106-107-
     110-116>118.
NE...None.

&&

$$

UPDATE...MAC
SHORT TERM...TJT
LONG TERM...RUBIN
AVIATION...SF