580
FXUS65 KCYS 051957
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
157 PM MDT Wed Jun 5 2024

.KEY MESSAGES...

- High winds will diminish this evening leading to a tranquil
  overnight.

- Warm weather will continue through late week, with widespread
  highs in the 80s and lower 90s on Thursday and Friday.

- Saturday through Monday will see increasing chances for
  afternoon and evening showers and weak thunderstorms. The
  warmest day will be Saturday with slightly cooler temperatures
  for Sunday and Monday.

&&

.SHORT TERM /THROUGH THURSDAY NIGHT/...
Issued at 133 PM MDT Wed Jun 5 2024

Generally tranquil weather is expected through the short-term
forecast period. Gusty afternoon winds are expected to quickly
diminish early this evening after sunset as surface pressure
gradients relax over southeast Wyoming. Expect light winds overnight
under mainly clear skies - a few isolated high cirrus clouds will
drift from northwest to southeast in the broad northwest flow
pattern over the high plains.

Unseasonably warm weather is again expected on Thursday across the
Nebraska Panhandle and southeast Wyoming. Subtle mid-level height
rises and lighter wind speeds will help add a few degrees to high
temperatures over the higher terrain. Temperatures from I-25
eastward will generally end up similar to today as a lack of
stronger downslope flow will help offset the slightly higher
heights. Overall, expect temperatures to end up around 15 degrees
above average. A few locations in southeast Wyoming such as
Cheyenne, Rawlins, and Laramie may end up within 5 degrees of record
high temperatures for early June. Expect isolated high clouds to
drift from west to east over the region on Thursday night with low
temperatures continuing to run around 5-10 degrees above average.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
Issued at 133 PM MDT Wed Jun 5 2024

Long Range forecast remains on track through the weekend and
into early next week. Models continue to show an early summer-
like pattern with a brief cool down during the weekend as the
upper level flow temporarily transitions to northwesterly flow
aloft. For Friday, expect the warmest day of the week as a
shortwave ridge axis/700mb thermal ridge quickly translates
across the area during the morning. Should be a very warm or a
little hot with highs in the mid to upper 80s in most
locations, and generally in the low to mid 90s over the lower
elevations of western Nebraska and near the Wyoming/Nebraska
border. Models do show a surface cold front moving southward out
of Montana during the afternoon hours as the upper level flow
backs out of the northwest a bit behind the short wave ridge.
Winds are forecast to shift into the north and eventually into
the east later on Friday...which will result in cooler
temperatures. It looks like areas further south near or along
I-80 will be slightly warmer compared to areas north of the
North Platte River Valley, which may see some of that slightly
cooler air earlier in the day from the surface cold front.
Should see an increase in convection later in the day, but
coverage should be isolated or widely scattered at best, so kept
POP in the 20 to 35 percent range for now.

Cooler temperatures expected this weekend as the upper level
flow becomes more northwesterly on Saturday and Sunday. Surface
winds will shift into the east or southeast across most of the
area with broad upslope flow in the low levels. Further west,
winds will remain out of the west or northwest resulting in
convergence near the Laramie Range. Models show a good chance at
widespread showers and thunderstorms along and east of the
mountains, including far western Nebraska. Kept POP between 60
to 80 percent in these areas with lower values further north
towards Douglas and Chadron Nebraska. Models show 700mb
temperatures hovering around 10c, so highs in the low to mid 70s
are a good bet. However, if cloud cover lingers through most of
the day, temperature may struggle to reach 70 degrees. Cloud
cover and cooler temperatures aloft on Sunday will result in
highs in the upper 60s to lower 70s across most of the area
Sunday afternoon. The only exception will be Carbon County,
which will be west of the frontal boundary with highs near 80.
There is considerable uncertainty with timing and coverage of
strong to severe thunderstorms this weekend. At this time, looks
like Saturday will have a very low chance due to limited CAPE
and cloudy skies as the cooler airmass settles into the Front
Range. Sunday looks like more probable day for severe weather
based on deterministic guidance. However, ensemble guidance
shows the opposite, favoring Saturday afternoon and evening.
Will continue to monitor, but both days may end up being
marginal days if current trends continue.

For early next week, models and ensembles favor a slow warm-up
as we head into Tuesday and Wednesday with highs returning to
the 80s. There are some diverging model solutions on Monday as
another Pacific shortwave pushes across the area, but guidance
shows temperatures increasing back above normal with another
round of showers and thunderstorms Monday afternoon.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 1114 AM MDT Wed Jun 5 2024

VFR will dominate at all terminals through the forecast period.
Expect gusty afternoon winds to quickly diminish by sunset with
generally light winds and clear skies expected through the
overnight at all terminals.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...High Wind Warning until 6 PM MDT this evening for WYZ109-110.
NE...None.

&&

$$

SHORT TERM...MAC
LONG TERM...TJT
AVIATION...MAC