Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 260451
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
1051 PM MDT Wed May 25 2022

.SHORT TERM...(Tonight through Friday night)
Issued at 225 PM MDT Wed May 25 2022

The CWA was sandwiched between a upper low over the east-central
Great Plains and upper ridge over the Intermountain West. The
resultant flow aloft was north-northwest. Some high clouds were
passing across northern WY, with scattered diurnal cumulus clouds
over the higher terrain and NE Panhandle. A modest low level
pressure gradient produced gusty northwesterly winds of 25 to 40
mph. Temperatures were 5 to 10 degrees warmer than 24 hours ago.

Looking at a fairly benign short term weather-wise with ridging
at the surface and aloft the dominant feature. As the ridge slowly
shifts to the east, winds aloft will back from northwesterly
Thursday to southwesterly Friday. It will be breezy Thursday for
southeast WY. The increasing southwesterly flow will raise sustained
wind speeds to 20 to 30 mph Friday. Gusts of 30 to 40 mph are likely
west of I-25 during the afternoon. Precipitable water values will
remain under 0.25 inch. Mid/upper clouds will increase from west
to east well in advance of a Pacific low pressure trough moving
into the western CONUS. Temperatures will warm each day as 700mb
temperatures rise from 6 to 12 degrees Celsius Thursday to 10 to
16 degrees Celsius Friday. Downsloping lee of the Laramie Range
will aid in the warming Friday, with high temperatures in the 80s
to lower 90s for the eastern WY plains and western NE Panhandle.
Models are showing a weak disturbance moving across southern WY
and northern CO Friday afternoon, however thermodynamic (sounding)
profiles are not favorable for significant convection due to a
capped environment.

.LONG TERM...(Saturday through Thursday)
Issued at 311 AM MDT Wed May 25 2022

Key Impact Messages:

1) Slightly above normal temperatures initially Saturday and mostly
dry conditions. Cooler temperatures late weekend to early next week
with rounds of lower elevation rain and higher elevation mountain
snow probable.

Weather Details: Starting the weekend, dProg/dT global guidance
models indicate increasing SW H7-H5 flow as a longwave trough pivots
on to the Pacific NW coast. Several shortwaves are progged to pivot
through this larger feature Sunday and into early next week. This
larger NW US gyre will bisect Wyoming with a colder airmass central
and west and warmer airmass east and across Nebraska Sunday into
Monday. The H7 front will waffle back and forth Sunday with an
initial passage late Sunday into Monday but then could shift back
west and stall over the area late Monday into Tuesday. With embedded
shortwave impulses riding overtop of the nearby boundary, several
rounds of precipitation do appear probable late weekend into early
next week. Amounts still remain in question depending on parent
closed low that develops west of WY with EC and GFS having
differences and run-to-run inconsistencies. There is certainly a
pattern for precipitation but the nuances of boundary positioning,
trough positioning, and impulse locations in the SW flow remain to
be resolved at this time. Will generally follow long range NBM
guidance at this time until a more clear signal can present itself.
Current GFS is farther south, slower, and then kicks a strong
negative tilted trough through the region mid-week next week while
the EC remains farther north and west with the parent closed low
with general SW flow as it shifts farther NE with weaker forcing.
Summarizing, a favorable pattern for precipitation will occur this
late weekend to early to mid next week but several variables will
determine just how much high plains rain and mountain snow could be
possible. Regardless, any moisture will be welcomed. Below normal
temperatures likely Monday through Wednesday into next Thursday.

&&

.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1042 PM MDT Wed May 25 2022

VFR at all terminals through the forecast period. Breezy winds are
expected to occur for Southeast WY on Thursday afternoon for gusts
up to 15-25kts from 15Z to 1Z. Wind gusts of 12kts or less can be
expected for the Nebraska Panhandle on Thursday.

&&

.FIRE WEATHER...
Issued at 225 PM MDT Wed May 25 2022

A ridge of high pressure will build over the districts through the
end of the week. A modest westerly flow aloft will promote breezy
conditions each day. Temperatures will warm each day, with the
warmest day Friday. Minimum relative humidities will decrease to
15 to 20 percent. Southwesterly flow aloft in advance of a Pacific
low pressure trough will increase moisture levels this weekend.
Surface low pressure developing in eastern Colorado Saturday will
intensify Sunday as it enters the central Great Plains. These
weather systems will produce cooler temperatures as well as
scattered showers and thunderstorms.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...None.
NE...None.
&&

$$

SHORT TERM...MAJ
LONG TERM...JA
AVIATION...BW
FIRE WEATHER...MAJ


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