593
FXUS65 KCYS 230901
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
301 AM MDT Mon Sep 23 2024

.KEY MESSAGES...

- Patchy frost is possible early this morning in low-lying and
  wind sheltered areas.

- Above average temperatures and dry conditions expected for the
  second half of the work week, with increased fire weather
  concerns Wednesday onward.

&&

.SHORT TERM /THROUGH WEDNESDAY/...
Issued at 255 AM MDT Mon Sep 23 2024

Latest GOES WV imagery shows a compact upper level shortwave
progressing eastward along the KS/NE border that brought
precipitation to much of northern CO last night. Cooler air
from this system remains in the vicinity tonight with various
sites dropping into the upper 30s at this hour, mainly in the
valley locations around Laramie and Saratoga where the low-
levels have become decoupled. Localized frost will be possible
early this morning for locations that can avoid mixing from
aloft, however latest RAP analysis shows a notable pressure
gradient east of the lee trough with another approaching
shortwave from the northwest. Additionally, westerly winds off
the Laramie Range will keep portions o the I-25 corridor,
including Cheyenne, slightly warmer through the night. This
disturbance will be much less potent than the previous system in
northern CO, but cannot rule out isolated shower development
late this afternoon in the NE panhandle. Forecast soundings
suggest dry low-levels with surface dew points only in the upper
20s. With generally weak forcing, any precipitation will likely
evaporate before reaching the ground.

Tuesday will be ~5F degrees cooler across the NE panhandle
behind the weak frontal passage. Overall, most of the CWA will
reach the 70s before the warmup into late this week begins.
An upper level ridge will begin to develop over the central
Rockies as 500mb height rises close to 588-590 dam. Latest NAEFS
guidance shows this around the climatological 98th percentile
for late September supporting afternoon highs 10-15F degrees
above normal starting Wednesday.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
Issued at 255 AM MDT Mon Sep 23 2024

The medium range to extended forecast remain unchanged as there is
very little with regard to weather in the next several days. We will
have above average temperatures and below normal chances for
precipitation through early next week. A predominant upper level
ridge pattern will become entrenched across the Intermountain West
and Great Basin. This will become an omega block weather regime
where weather disturbances propagate to our north and east as the
next several days occur. Expect daytime highs in the 70s and 80s for
the lower terrain, and slightly cooler in the mountain zones. By
early next week, a potential shift in the upper level steering flow
will cause a shortwave trough and associated cold front to move
towards our cwa. Cooler temperatures are progged to then be
prevalent for the time being.

&&

.AVIATION /00Z TAFS THROUGH 00Z TUESDAY/...
Issued at 530 PM MDT Sun Sep 22 2024

Upper level trough, south of the area, is forecast to slowly move
eastward and weaken over the next 24 hours. Decreasing cloudiness
and relatively light winds are expected.

HAZARDS/WEATHER TRENDS: VFR conditions will continue over the next
24 hours with minimal impacts to aviation. The probability of fog
over the Nebraska Panhandle terminals is below 5 percent tonight.

&&

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

&&

$$

SHORT TERM...MB
LONG TERM...BW
AVIATION...SF