715
FXUS65 KCYS 102328
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
528 PM MDT Sun May 10 2026

.KEY MESSAGES...

- Mostly dry and warmer weather will prevail for Sunday through
  Wednesday, with thunderstorms possibly returning late in the
  week.

- Elevated to Near Critical fire weather conditions possible
  over east central Wyoming and the northern Nebraska Panhandle
  Monday afternoon.

&&

.SHORT TERM /THROUGH TUESDAY NIGHT/...
Issued at 210 PM MDT Sun May 10 2026

Quiet conditions expected through the start of the work week,
though that will lead to increasing warmth and elevated fire
weather concerns. For the rest of today through Monday, expect
warming to continue as ridging moves over the region, with
highs shooting up significantly on Monday. Aloft, temperatures
at 700 mb will peak between 10-13C, translating to highs at the
surface in the upper 70`s to upper 80`s, with low 90`s as we
move into the Nebraska Panhandle. Many sites will be knocking on
the door of record highs, so don`t be surprised if a site or
two at least ties the daily highs if we can get warm enough.
Meanwhile this record warmth will also be in tandem with a
notable lack of moisture as Relative Humidity values for the day
descend into the low teens to near single digits. This will
bring a widespread elevated fire weather concern, but at this
time we have held off on issuing red flag warnings for various
reasons. While winds will likely line up with these low RH
values in Converse and Niobrara Counties, reports of greenup may
be enough to hold off on issuing Red Flags at this time (though
we are in contact with our fire weather partners on how true
that may be). Meanwhile for the Nebraska Panhandle, winds are
not currently expected to stay strong enough for 3 hours to
produce Red Flag conditions. Looking again at 700mb, a quick hit
of winds does occur during the afternoon into the evening,
which may mix down, but this is for a brief period of 1-2 hours
and struggling to increase winds using 90th percentiles to
justify critical fire weather conditions. Will continue to
message elevated concerns and pass this to incoming shifts to
further analyze in case a last minute upgrade to Red Flag
Warning is needed.

Into Monday evening and through Tuesday, a quick moving weak
cold front will pass across the region, and should cool our
highs on Tuesday back into the 70`s to low 80`s (though this
will still be around 8-12 degrees above normal). This cold front
should bring our temperatures down just enough that fire weather
concerns should be low to perhaps slightly elevated, as some
sites in the Nebraska Panhandle may see RH values bottom out in
the upper teens for the day. The passing system will also bring
a chance at a very isolated passing shower in the high terrain,
but the risk remains minimal overall with a lack of more
significant moisture as PWAT values remain rather dry at around
0.25 - 0.5 inch, alongside of course stronger forcing.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
Issued at 210 PM MDT Sun May 10 2026

An upper level ridge will be centered over the New Mexico and
Colorado area with an axis extending north over our area and into
Canada. This kind of pattern should favor dry and clear conditions
for much of our area. The daytime mixing of the boundary layer will
dry out the surface while sinking air from the ridge will heat up
the surface. Sampling the GFS model during the afternoon hours of
Wednesday is indeed showing these conditions with a nearly 50 degree
spread in surface temperatures and dew point temperatures. Maximum
temperature will be flirting with daily record highs in some spots
with widespread 80s and 90s. Relative humidities will drop into the
teens and even single digits for areas in Carbon County. Surface
trough development is being depicted in global models just to our
north. During the afternoon a corridor of stronger flow to the
southwest of this low will collocate with the driest conditions in
Carbon and Albany Counties that afternoon. Sustained winds of 30 mph
and higher gusts may be possible, though these details are murky
being a few days out and depending on the strength of the surface
low. Overnight humidity recoveries are expected to be poor for
locations west of the Laramie Range. Regardless the pattern does
favor elevated fire weather concerns at a minimum and interests
should monitor conditions and forecasts for Wednesday and the next
following days.

Thursday continues the dry conditions of Wednesday. We do see some
monsoonal type moisture funneling in from the Gulf of California and
the East Pacific that could be enough to create isolated showers and
thunderstorms. PoPs are not high with current forecasts calling for
around 20% chances at most. GEFS members give about a 20-40% chance
of some areas in the CWA receiving 0.05" of rainfall. Given the
fairly dry conditions at the surface most precipitation will
evaporate on its way down from cloud level. The ridge axis that had
been parked overhead the last few days should start to slide
southeast, but dry and warm conditions will continue. Daytime
temperatures may climb into the mid to upper 80s for areas east of
the Laramie Range, with a slight cooling for the interior mountain
regions. Relative humidity values remain low, in the teens, so fire
weather concerns continue.

About this time a compact, high amplitude negatively tilted trough
will be making its way in from the northwest. Compared to
yesterday`s guidance, the placement of this trough is trending
southward and slower. The surface low that forms Wednesday may be
tugged south to met this upper level trough during the day Thursday
and Friday. We will likely remain on the dry side of this surface
low. With the southward position of the upper level feature our high
wind chances have decreased for Thursday, but gusty winds are still
likely. Additionally, thunderstorm chances do not seem to have
gotten better with this placement given the shut-off of surface
moisture under the favorable portions of the jet, though details are
still uncertain at this range. There was a slight increase in storm
potential from machine learning models for the Nebraska Panhandle
for what it is worth. The most likely outcome is a capped
environment there.

Friday through the weekend portion of this outlook are appearing
cooler following the departure of the upper level system. Another
ridging pattern may setup for Friday and Saturday. Dry conditions
continue with daytime humidity minimums dropping below 20%.

&&

.AVIATION /00Z TAFS THROUGH 00Z TUESDAY/...
Issued at 527 PM MDT Sun May 10 2026

VFR conditions will be in place throughout the TAF period as
longwave ridging builds in from the west. A few high clouds will be
present, but no low clouds/ceiling issues during this time. Winds
are expected to remain variable in direction and below 10 knots
through the overnight period, before our Wyoming terminals are
expected to see winds ramp up after sunrise, mainly out of the WSW
to around 15 knots. As we head into the afternoon hours, gusts are
anticipated to increase to 25-30 knots as gradient flow strengthens
thanks to weak lee cyclogenesis occurring to our north over
South Dakota.

&&

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

&&

$$

SHORT TERM...CG
LONG TERM...RV
AVIATION...NB