Cheyenne, Wyoming 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

078
FXUS65 KCYS 112051
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
251 PM MDT Fri Apr 11 2025

.KEY MESSAGES...

- Expect another round of near record high temperatures on
  Saturday. Gusty winds will increase fire danger across much
  of southeast Wyoming.

- A cold front will arrive on Sunday dropping temperatures back
  to near climatological average for Sunday and Monday.

&&

.SHORT TERM /THROUGH SUNDAY NIGHT/...
Issued at 300 PM MDT Fri Apr 11 2025

The axis of a strong ridge aloft is moving across the area today,
supporting a very warm spring day! Temperatures are surging well
above average across the area, with all population centers into the
70s, and even crossing 80F at Kimball so far. While boundary layer
humidity remains extremely low with dewpoints in the single digits
to teens, winds have luckily remained below criteria for a Red Flag
Warning in the areas where the fuels are ready to burn. However, mid
to upper level moisture is on the increase today. Current GOES
satellite imagery shows increased cloudiness streaming northeastward
over the top of the ridge on its upstream flank.

A subtle shortwave trough ridging over the crest of the ridge this
evening will carry with it a weak surface trough moving across the
area overnight. This will help weaken southerly winds and shift the
surface flow to the west or northwest by Saturday morning over the
High Plains. After sunrise, expect a subtle boundary to set up
across the area near the North Platte River valley, with north to
northeast winds to the north bringing in slightly cooler and wetter
air, while areas to the south remain very warm and dry. Increasing
southwest to west winds ahead of the approaching trough will aid
downslope warning and lead to temperatures near to a few degrees
warmer than today south of the surface boundary despite the increase
in cloud cover. Saturday will be a fairly windy day along and south
of the North Platte River valley with increasing winds aloft easily
reaching the surface in the deep, well-mixed boundary layer.
Widespread gusts of 40 to 50 mph look like a good bet, particularly
in Carbon and Albany counties. Reaching High Wind criteria is a bit
more uncertain, but there is about a 30 to 40% probability of high
winds in the wind prone areas favored by southwest flow, as well as
in Rawlins. Will hold off on any wind headlines for now, but this
will warrant another look with the next forecast package. Thanks to
the increase in wind speeds, Saturday will also bring widespread
critical fire weather conditions to most of southeast Wyoming.
However, the forecast is more marginal in areas where fuels are
critical (Converse, Niobrara, and the Nebraska panhandle). While
much of the area will probably see briefly critical fire weather
conditions, there is some uncertainty on the duration criteria since
the surface boundary may keep them out of the very warm/dry airmass
until mid afternoon. So for now, no headlines will be issued, but
planners should be prepared for widespread critical fire weather
conditions. Lastly for Saturday, a few isolated showers/storms will
develop in the ample mid to upper level moisture during the evening
hours. This activity may produce some dry microbursts with gusty and
erratic surface winds.

The surface cold front associated with a stronger shortwave trough
aloft will pass through Saturday evening, bringing a period of gusty
northwest winds along with a temperature drop and increase in
boundary layer moisture. This will push southward and stall
somewhere between the WY/CO border and central Colorado as another
weak ripple/vort-max traverses across the mid-level boundary Sunday
afternoon through the evening. This will kick up a brief period of
positive isentropic lift and support developing rain/snow showers
along the stalled boundary. However, only about 20% of ensemble
member stall the boundary far enough north to bring more than a
tenth of an inch of liquid precipitation to the I-80 corridor, while
the others keep most of the precipitation to our south. While we
maintain some slight chance to chance PoPs (15 to 40%) for the I-80
corridor and points southward, the most likely scenario at this time
is for appreciable precipitation to stay largely to our south.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
Issued at 300 PM MDT Fri Apr 11 2025

Monday morning could have a wet ground from the
possible overnight showers along the I-80 corridor west of I-25. But
other wise Monday will be roughly the same temperature as Sunday
with the cooler airmass overhead and the approaching ridging pattern
off to our west. Tuesday and Wednesday will be much like the
previous week with the Intermountain west under an upper level ridge
to warm us up and keep temperatures in the 60`s and 70`s. However,
Wednesday evening and into Thursday a low pressure system descends
down from Manitoba, CA to flatten our ridge and start the next round
of precipitation chances. The 700mb pressure gradient begins to
tighten to give us some breezy winds Thursday. Depending on how far
south the low pressure system descends will increase the breeziness
throughout the day Thursday and drag those precipitation chances
further south into Southeast Wyoming and the Nebraska Panhandle. The
12z run of the global model soundings due project a pretty stout dry
layer near the surface once again. This is also mainly due to our
region being in a downslope westerly flow Tuesday and Wednesday to
help reinstate the dry air that may have possibly be lost during the
the previous shortwave. This stout dry layer may prevent most of the
precipitation from reaching the ground as the most of the
precipitation may evaporate and help saturate the air before then.
Otherwise, another ridging pattern follows the heels of this low
pressure system for dry conditions Friday and potentially the
weekend but there is another potential system that could leave us a
little wet this weekend as well. There is a lot of model
disagreement with next weekends system but, it is worth monitoring
for potential precipitation chances.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 1118 AM MDT Fri Apr 11 2025

An upper level ridge continues to sit over Southeast Wyoming and
Nebraska Panhandle. There will be some medium to high based
clouds (10,000-20,000ft) moving through our TAF sites this
evening and overnight period. Therefore VFR conditions will
continue through the TAF period.

&&

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

&&

$$

SHORT TERM...MN
LONG TERM...MM
AVIATION...MM