Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 022339
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
539 PM MDT Sat Jul 2 2022

.SHORT TERM...(This evening through Monday night)

Issued at 315 PM MDT Sat Jul 2 2022

The main challenges of the short term forecast concern the daily
chances for thunderstorms through the rest of the holiday weekend.

The weather pattern continues to remain failure stagnant as an upper
level low parks itself over the Pacific northwest coast through the
rest of the weekend. Between the low and a ridge over the central
plains, southwest flow aloft continues to push good monsoon moisture
out of the southwest into our area. This pattern is expected to be
stuck in place for several more days, but moisture availability will
fluctuate.

Currently, GOES satellite imagery shows clear skies over much of the
area, but cumulus clouds are bubbling up over the higher terrain and
starting to drift eastward. Weak low level south to southeasterly
flow is present east of the Laramie range on the periphery of a
subtle surface high located over the northern plains. Precipitable
water has declined slightly since yesterday after a slight weakening
of the monsoon push, but low level moisture over the high plains is
a touch higher than initially forecast, possibly related to residual
moisture from yesterday`s storms. Dewpoints in the 50s are present
cross most of the Nebraska panhandle, and are also creeping up the
North Platte River valley into Wyoming. Mesoanalysis shows SBCAPE of
around 1000-1500 J/kg in this area and modest 0-6km shear around 30-
40kts. The environment is not as supportive as yesterday, but
scattered storms today may still produce some gusty winds and
perhaps small hail. A quiet and mostly clear night is expected after
storms wane late this evening.

On Sunday, a subtle shortwave will rotate through the nearly fixed
upper level flow pattern and provide some additional lift. This will
also enhance the southwesterly flow aloft and help to nudge PWATs
upward. An overnight push of low level moisture on the high plains
will help to push dewpoints to near or above 60F in our eastern row
of counties in Nebraska for Sunday morning. However, lee troughing
will start to develop east of the mountains later in the day on
Sunday which may nudge the moisture plume further east. Since
mid/upper level moisture should remain fairly strong, forecast
soundings are showing some inverted v`s across the area during the
afternoon. Thus, looking at another day with a threat for gusty
winds. Lapse rates will be quite steep but shear should be modest,
so we could have some isolated large hail. Overall, looking at
greater storm coverage than Saturday thanks to the additional
moisture and lift aloft, with a primarily wind and possibly hail
threat across the high plains. The SPC has already highlighted
portions of the Nebraska panhandle with a slight risk.

The longwave trough will push slightly eastward on Monday which will
tilt the monsoon plume eastward and allow much drier air to filter
in across Nevada, Utah, and western Wyoming. The strengthening
surface low pressure over our area will also push the low level
moisture plume even further east. Still should be sufficient
moisture to kick off isolated storms from the higher terrain, but
coverage should be lower. Still, nudged PoPs up from the NBM to keep
a slight chance of storms in the forecast for areas east of the
Laramie range. Temperatures on Sunday and Monday look warmer than
the last few days as the downstream ridge amplifies.

.LONG TERM...(Tuesday through Saturday)
Issued at 315 PM MDT Sat Jul 2 2022

Drier Tuesday as forecast PWATs drop to .5 inches west of the
Laramie Range. Still pretty high across the Panhandle with mid to
upper 50 dewpoints. Have a surface trough pushing into northeast
Wyoming and southwest South Dakota.

Surface trough settles in across the area Wednesday and Thursday
as forecast PWATs rise in advance of a monsoon surge. Best
chances look to be Thursday.

Drier for Friday into the weekend as upper high builds into the
area with moisture sliding east.

&&

.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 527 PM MDT Sat Jul 2 2022

VFR for all terminals through the forecast period. A stray shower
may approach a terminal this evening, but due to low confidence,
it was left out of TAFs for any terminals. Gusty winds to 20 kts
are possible through approximately 02Z this evening before
dissipating to approximately 12 knots or less overnight. Southerly
winds will begin to take hold by Sunday morning, with gusts of
20-25 knots at all terminals by mid to late morning through Sunday
afternoon.


&&

.FIRE WEATHER...
Issued at 315 PM MDT Sat Jul 2 2022

Minimal fire weather concerns through tomorrow, but drier air
working in next week may start to increase concerns once again. The
last two days have brought widespread wetting rains across our area.
While storms are not expected to be as wet or widespread this
afternoon, a few locations may see another round of wetting rain.
Today`s storms may also bring some gusty winds and lightning. Sunday
will be similar, but storms may be slightly more widespread as
monsoonal moisture creeps back up. Gusty winds and lightning will
remain a threat for Sunday.

Drier air starts to work back in on Monday from the west as the
monsoon push fluctuates. Elevated fire weather conditions are
possible in our western counties (Carbon/Converse) with min RH in
the upper teens and some breezy conditions possible. Monday`s storms
will be more isolated. The rest of the period will continue to be
characterized by fluctuating monsoon moisture, but increasing heat
and weakening low level moisture may lead to increased fire weather
concerns next week.

&&

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

$$

SHORT TERM...MN
LONG TERM...GCC
AVIATION...BW
FIRE WEATHER...MN


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