873
FXUS65 KCYS 260919
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
319 AM MDT Thu Sep 26 2024

.KEY MESSAGES...

- Elevated to critical fire weather conditions are expected
  today. A Red Flag Warning remains in effect for parts of
  southeast Wyoming through 8pm MDT.

- Above average temperatures and dry conditions expected for the
  forseeable future.

&&

.SHORT TERM /THROUGH FRIDAY NIGHT/...
Issued at 303 AM MDT Thu Sep 26 2024

Latest surface analysis depicts a cold front pushing from the
Pacific Northwest and inching closer to the Intermountain West, with
several shortwaves digging across the CWA kicking up some gusty
winds across the wind prone areas. Outside of some increased wind
speeds from 25 to 35 mph for both KBRX and KARL, observations have
been relatively mild with temperatures in the low to mid 50s and
clear overhead skies for both southeast Wyoming and the Nebraska
Panhandle.

Very little changes to the near term forecast, with the latest upper
air analysis having the ridge axis centered across the High
Plains, which is expected to shift slightly eastward as an upper
level shortwave passes to the north and a developing blocking
pattern shifts southward into the Four Corners. Under this
setup, will see the southwesterly flow transition to warming
downsloping westerly flow for much of our region. A significant
warmup is still on track for today, with 700mb temperatures
expected to climb upwards to around +16c and the resulting warm
downsloping flow increasing surface temperatures into the high
80s to low 90s for southeast Wyoming and into the high 90s for
the Nebraska Panhandle. Kept with the trends of blending in
higher NBM percentiles into the short term forecast, with the
NAEFS mean 700mb temperatures in the climatological 99th
percentile for the majority of areas across southeast Wyoming
and the Nebraska Panhandle.

Main concerns in the forecast remained focus on the prolonged
dry conditions, combined with the much warmer temperatures
today, which will inevitably raise fire weather conditions as
the minimum RH values drop to the mid to low-teens for much of
southeast Wyoming and the Nebraska Panhandle. Wind speeds will
remain the main uncertainty and if they are able to reach
critical thresholds. Nevertheless, HREF probabilities of
reaching critical fire weather conditions have continued to
trend upwards for southeast Wyoming where current Red Flag
Warnings are in effect through 8pm MDT tonight.

Slight cooldown is expected Friday, with a weak surface front
progged to dig southward through the area early Friday morning
and dropping temperatures a good 10 degrees from today.
Although, should be relatively short lived with the upper level
ridge pushing more northward in the Dakotas by this weekend. As
a result, another above average temperature day expected on
Saturday, with NAEFS mean 700mb temperatures in the
climatological max for portions of southeast Wyoming and the
remaining areas in the 90th to 99th percentiles. Similar to
today, continued mixing in higher NBM percentiles to the current
blends to continue increasing daytime high for Saturday.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
Issued at 303 AM MDT Thu Sep 26 2024

Dry weather will dominate the long-term forecast period. Not much
change in overnight ensemble guidance with very high forecast
confidence in no precipitation in southeast Wyoming and western
Nebraska through this period. From a large-scale synoptic
perspective, a broad ridge of high pressure will generally be in
control through Sunday night. This upper-level ridge will become
suppressed to the south by Monday as a broad trough moves through
the far northern CONUS. At the surface however, things will be a bit
more exciting as this broad trough will drive a surface cold front
southward through the high plains on Monday. After several days of
well-above to near record high temperatures, expect a return to near-
normal temperatures on Monday for highs behind this cold front.
Clear skies and a very dry, post-frontal airmass will result in a
chilly fall night on Monday night into Tuesday with an outside chance
of frost possible in  places like Laramie, Rawlins, Cheyenne and
even some of the typically colder locations in the high plains and
western Nebraska. After another seasonable day on Tuesday,
temperatures rebound by midweek as fast westerly flow enhances a
broad downslope pattern by midweek. It looks very likely that the
dry weather pattern will continue right through the end of next week
and possibly even into the following weekend given robust ensemble
pattern agreement showing zonal flow and PWAT values well below
average.

&&

.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 530 PM MDT Wed Sep 25 2024

A strong upper level high pressure for late September will push east
into the Great Plains tonight and Thursday. This will result in a
continuation of quiet weather.

HAZARDS/WEATHER TRENDS: VFR conditions will continue over the next
24 hours. Breezy conditions for KCDR with gusts up to 30 knots
possible between 04z and 11z Friday.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...Red Flag Warning from 11 AM this morning to 8 PM MDT this
     evening for WYZ417>422-427-432.
NE...None.

&&

$$

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