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198
FXUS65 KCYS 222024
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
224 PM MDT Sat Jun 22 2024

.KEY MESSAGES...

- Warmer and drier trend starting today, but cannot rule out
  gusty winds with high-based storms in the afternoon near the
  CO/WY border.

- Hot temperatures in the upper 80s to 90s are expected for
  Sunday through much of next week. Elevations below about 4500
  feet may exceed 100F.

&&

.SHORT TERM /THROUGH MONDAY NIGHT/...
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Issued at 225 PM MDT Sat Jun 22 2024

Frontal boundary lays pretty near Cheyenne this afternoon and
lays north of Cheyenne to Douglas into northeast WYoming. This
boundary is separating dewpoints in the 30s west of the front
with upper 40s/low 50 dewpoints in the Panhandle. Radar is
pretty quiet this afternoon. We did have some showers/storms
develop along the state line with Colorado out by Laramie...but
storm motions have been southeast into northern Colorado.
Current GFS 700mb temperatures at 21Z around +10C over the
northern Panhandle to +15C over southern Carbon County. This has
yielded temperatures across the CWA from the mid 80s in the
Panhandle to near 80 at Rawlins so far this afternoon. PWAT
values have really dried out as well with .65 inch near Sidney
and .49 inch out by Rawlins.

Not expecting much for afternoon convection across southeast
Wyoming this afternoon. Mesoanalysis RAP surface based CAPE
only around 500 J/KG through the afternoon. HRRR/RAP simulated
radar only showing a few storms across northern Colorado with
nothing really on our side of the state line. Any convection
that does develop this afternoon is expected to die off pretty
quickly as temperatures cool late afternoon/evening.

For Sunday...700mb temperatures climb to +14C across the
Panhandle to +16C across Carbon County. Look for highs Sunday in
the mid to upper 90s in the Panhandle to upper 80s/low 90s west
of the Laramie Range. Dry and sunny conditions expected.

Begin to see an increase in showers Monday...mainly west of the
Laramie Range during the afternoon. These will likely be high
based storms with little to no rainfall. ECMWF and GFS showing
an increase in moisture from the south in western Colorado
making its way into southern Carbon and Albany Counties.
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&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
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Issued at 225 PM MDT Sat Jun 22 2024

Warm temperatures continue into the long term with near daily
chances for showers and thunderstorms. A ridge of high pressure over
the Desert Southwest will persist throughout much of next week. This
will lead to +14C to +18C 700 mb temperatures hanging over the CWA
through Friday. As a result, temperatures across much of the area
will be above average and roasty. Tuesday through Thursday will see
highs across much of the area in the upper 80s to 90s. Although the
region will be under the influence of a ridge, it is a dirty ridge,
with fairly decent precipitation chances on Wednesday and Thursday.
An upper-level disturbance moving across the ridge on Wednesday
could spark some scattered convection. GFS soundings for Wednesday
afternoon indicate that severe weather cannot be ruled out. Inverted-
V soundings and MUCAPE values up to 2000 J/kg in the Nebraska
panhandle could lead to a severe wind and hail threat. Model
soundings on Thursday do not look conducive for severe weather, but
another weak disturbance aloft could lead to another round of
afternoon storms.

By Friday, a shallow trough will begin enter the central Rockies,
cooling temperatures off a few degrees and brining more
precipitation chances. Once the cold front is through Friday
evening, expect a larger cool down, with highs near to slightly
below average on Saturday.
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&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1124 AM MDT Sat Jun 22 2024

Much drier and warmer atmosphere over southeast Wyoming and
Nebraska Panhandle the next 24 hours and beyond will lead to VFR
conditions and no weather impacts. Gusty west to northwest
winds this afternoon will die down after 00Z.

&&

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

&&

$$

SHORT TERM...GCC
LONG TERM...SF
AVIATION...GCC