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000
FXUS65 KCYS 170535
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
1135 PM MDT Tue Apr 16 2024

.KEY MESSAGES...

- Widespread rain and snow showers will return to much of the
  area on Wednesday and Wednesday night. Accumulating mountain
  snow is possible, especially in the Snowy Range with 6 to 12
  inches of new accumulation possible above 9000 feet.

&&

.UPDATE...
Issued at 633 PM MDT Tue Apr 16 2024

High Wind Warnings for the remaining areas across the eastern
high plains were allowed to expire at 6 PM this evening as winds
have continued to diminish. No other updates are anticipated for
this evening and tonight.

&&

.SHORT TERM /THROUGH WEDNESDAY NIGHT/...
Issued at 224 PM MDT Tue Apr 16 2024

Isolated to widely scattered (very light) showers may still be a
possibility across southeast WY & the western NE Panhandle given
warming surface temperatures & continued influence from the mid-
level cold core associated w/ the departing surface cyclone. Dry
conditions should prevail for the majority of areas, with little
to no chance for any additional measurable precipitation through
tonight. Strong winds are likely to persist through sunset for a
large portion of the high plains, with widespread gusts 55 to 65
MPH still being observed as of 20z this afternoon. Expect to see
gusts decrease markedly over the next few hours w/ weakening low
level gradients and lapse rates, but occasional gusts to near 50
MPH could still be possible near Arlington and Elk Mountain thru
12z Wednesday as H7/H85 CAG-CPR gradients remain near 45 meters.
High Wind Warnings should expire as scheduled, but will continue
to closely monitor observational trends.

The improved weather conditions will be short-lived as the short
wave ridging aloft quickly gives way to broad, and low-amplitude
troughing over the northwestern CONUS by mid-day Wednesday. Mid-
level westerlies are expected to increase, along with strong sfc
gradients and 35 to 45 knots of 700-800 hpa flow over Carbon and
Albany counties atop steep low-level lapse rates. Wind gusts may
approach or exceed 50 MPH, but confidence in warning-level gusts
is not high enough to warrant any additional headlines with this
forecast package. Numerous rain & snow showers are also expected
to spread across a large portion of the CWA Wednesday afternoon/
evening w/ the passage of the next cold front. Any possible snow
accumulations should be confined to the higher elevations along/
west of the Laramie Range, but overall expect impacts to be very
low. An additional 6 to 12 inches may be possible in the Snowys,
possibly requiring a Winter Weather Advisory w/ future updates.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
Issued at 224 PM MDT Tue Apr 16 2024

The long term forecast includes an active weather pattern for early
spring, with multiple chances of precipitation, large temperature
swings, and, elevated winds at times. The first portion of the long
term forecast includes well below normal temperatures, with a brief
weekend warmup during the weekend, and then returning to slightly
below normal temperatures early next week.

Thursday will start off with our region being under the influence of
a large, negatively tilted H500 trough. The semi-zonal flow will
have just enough of a weak disturbance aloft to keep the
precipitation faucet running in the higher elevations for additional
chances of snowfall. There is also a weak signal for mountain wave
activity over the I-80 Summit, so will need to pay attention to that
in the next couple of days in case additional high wind headlines
seem prudent. At this time of inspection, highest confidence exists
in high levels of CAA occurring from the Canadian Provinces down to
our cwa. Further upstream across CA on Thursday and Thursday night,
another trough will propagate over the Great Basin and Intermountain
West. The Polar Jet and the Subtropical Jet do have a weak signal to
phase together overnight, and into Friday morning. The rear entrance
region of the Subtropical Jet may have just enough "juice" to give
areas along the I-80 corridor of snowfall accumulations. Cold air
will be entrenched across the region due to a cold FROPA, which
leads to higher confidence of snow shower activity being present for
the mountain zones and potentially the high plains. The NE Panhandle
may see a rain/snow mix during the daylight hours. Some of the model
guidance does hint at the subsequent Colorado Low taking a slower
time to eject out toward the Central Plains through Saturday, which
could induce a longer window for light snow showers to remain
present. Overall, expect daytime highs on Thu/Fri/Sat to be 10-20
degrees below normal.

By Sunday, we will begin to see the effects of upper level ridging
aloft. The WAA will bring daytime highs upwards of to 10 to 20
degrees warmer than Saturday. It will be a nice change up to the
recent well below normal temperatures from Thu-Sat. Expect to say
afternoon maximums in the 60s for the lower elevations, and the 40s
for the higher terrain elevations. Breezy winds in the wind prone
corridors are also highlighted in model guidance for Sunday, so we
can expect those wind gusts to mix down to the surface east of the
Laramie Range after atmospheric mixing begins to occur. There does
not appear to be strong enough winds aloft to encourage a watchful
eye for high wind headlines at this time of inspection.

The beginning of next week includes a large spread of deterministic
solutions to what weather and temperatures look like. Quasi-zonal
flow aloft will include nearby shortwave disturbances. Daytime high
temperatures have been nudged down a degree or two to reflect this
as we will be on the fringe of another push of colder air from
Canada. We will also have the chance for additional rain and snow
showers depending on whether the shortwave disturbances trek over
our cwa early next week. Stay tuned for forecast updates in the
coming days as we iron out these smaller details with higher
confidence.

&&

.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 1134 PM MDT Tue Apr 16 2024

VFR conditions at all terminals expected to remain for most of the
06Z TAF period. KRWl could see a few hours of MVFR ceilings in the
morning hours before improving back to VFR conditions by midday.
Winds are expected to decrease overnight at all terminals, but gusty
winds return tomorrow for all terminals. A cold front will push
through the area increasing winds throughout the day from KRWL to
KLAR to KCYS to all Nebraska terminals. Expect gusts to increase to
20-30kts once more across the region. Currently, there is an
indication that all Nebraska terminals will approach MVFR
toward IFR ceilings late in the TAF period. Additionally, could
see scattered rain showers across the Nebraska terminals
throughout the day.

&&

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

&&

$$

UPDATE...TJT
SHORT TERM...CLH
LONG TERM...BW
AVIATION...AM