222
FXUS65 KCYS 042054
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
254 PM MDT Thu Jul 4 2024

.KEY MESSAGES...

- It will be much cooler across much of the area this afternoon
  and on Friday. Daytime highs are expected to remain in the
  70s for most locations.

- Near to slightly below normal temperatures will persist over
  the next several days, with daily chances for isolated to
  widely scattered showers and thunderstorms. The threat for
  strong to severe thunderstorms should remain limited through
  at least Friday.

&&

.SHORT TERM /THROUGH SATURDAY NIGHT/...
Issued at 248 PM MDT Thu Jul 4 2024

A quiet weather day for most of the region behind a cold front
that swept through the region last night, remains across the
area. Surface observations are showing daytime highs in the 60s
and 70s for the cwa as of 20Z. GOES-16 satellite imagery is
showing a wide swath of fair weather cumulus, and a few isolated
rain showers east of the South Laramie Range. Expect this trend
to continue with wind gusts 10-20mph through the rest of this
afternoon, and a possible stronger wind gust if a weak
thunderstorm develops. Quiet conditions should prevail this
evening for those that plan to head outdoors for a holiday
event or two. One caution is that the flashy fuels are quite dry
for areas east of the Laramie Range, so fire spread is possible
for those that are the spark for isolated events.

Mostly quiet conditions are anticipated for Friday as well.
Daytime highs in the 70s for the majority of the cwa is likely,
with a few locations along the North Platte River Valley in the
NE Panhandle eclipsing the 80 degree mark. There will be a
slight chance of rain showers and isolated thunderstorms Friday
evening, but it will remain sub-severe. Saturday will be more of
the same, with temperatures becoming slightly warmer by the
afternoon. Expect daytime highs to be in the mid-70s to mid-80s
for most of the cwa, with the exception being in higher terrain.
Isolated chances for thunderstorms after 21Z through 3Z for the
I-25 corridor and east. We have a Marginal Risk for severe
weather on Saturday, so this may need another look in the next
12-24 hours for the potential of large hail and/or strong wind
gusts.



&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
Issued at 248 PM MDT Thu Jul 4 2024

The cool weather pattern will gradually break down over the course
of next week, with a return to hot weather increasingly likely by
the end of the week.

Sunday will be another cool day across the area behind the latest in
a series of troughs skirting down the eastern edge of the Rockies
this week. Longwave ridging continuing over the west coast and
troughing over the central US will continue to allow these cool
fronts to slip through our area through the weekend. High
temperatures look to run about 10-15F cooler than average Sunday
with 700-mb temperatures sitting below the 10th percentile in the
NAEFS mean and cloud cover lingering along/east of the Laramie
range. Frontogenesis running up against the mountains will lead to
some morning shower activity followed by another potential round in
the afternoon and evening hours.

Through the rest of the week, ensemble guidance shows the strong
ridge parked over the west coast gradually shifting eastward through
the week. Towards the end of the work week, the ensemble mean ridge
position is more or less over the Great Basin, which would gradually
transition our area to a much hotter pattern. Highs should return to
near average values Tuesday before creeping above normal again by
Wednesday or Thursday. While models have continually kicked the can
down the road with the eastward shift of the ridge over the last
week or so, they are pretty universally showing this occurring by
mid next week now. Precipitation opportunities during this period
will also be pretty limited, but not zero. Some ensemble members are
completely dry for nearly a week after 12z Monday, but other members
have isolated afternoon convection mainly over the higher terrain.
Widespread convective activity looks fairly unlikely though.

&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 1142 AM MDT Thu Jul 4 2024

VFR conditions expected for the forecast period. Breezy NW winds
will weaken and shift more northeast around sunset, with normal
diurnal winds resuming after midnight. A few showers/weak
thunderstorms are possible this afternoon around KCYS and KCDR.
Another round is possible between about 04z and 10z, mainly
around KBFF.

&&

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

&&

$$

SHORT TERM...BW
LONG TERM...MN
AVIATION...MN