-- Discussion containing changed information from previous version are highlighted. --
252
FXUS65 KCYS 231706
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
1106 AM MDT Sun Jun 23 2024

.KEY MESSAGES...

- Hot temperatures are expected today through the middle of next
  week. Highs exceeding 100F are possible for elevations
  generally below 4500 feet.

- A few isolated showers/weak thunderstorms may bring gusty
  winds to parts of southeast Wyoming today. Monday looks
  similar, but with slightly greater storm coverage.

&&

.SHORT TERM /THROUGH MONDAY NIGHT/...
Issued at 424 AM MDT Sun Jun 23 2024

There is hardly a cloud in the sky across the forecast area this
morning as a fairly benign ridge strengthens over the southwest
CONUS. The pseudo-monsoonal plume that brought moisture to the area
late last week is not tilted to the east with drier air over the
central and northern Rockies. Once the sun comes up, we`ll be set to
warm up very quickly today. Today will be one of, if not the hottest
day of 2024 so far. 700-mb temperatures were analyzed around +14C
this morning, but should climb to +16 to +18C by the afternoon.
Expect to see highs in at least the upper 80s, but with most seeing
90s. Scottsbluff and Torrington will make a run at 100F today (60%
odds in Scottsbluff), and can`t rule out triple digits at other
locations below about 4500 feet. Afternoon convection will be
similar to yesterday across the area, with just a few very isolated
high based showers/weak thunderstorms expected to develop. Forecast
soundings today indicate some moisture right around 500-mb, but
pretty dry conditions both above and below. As a result, storms will
struggle to drop more than a few hundredths of rain at best, and may
just lead to some gusty winds mostly between 2PM and 8PM in Carbon,
Albany, and Laramie counties. A light southwest breeze through the
night will probably lead to a pretty warm night along the Pine
Ridge, north side of the Cheyenne Ridge, and north/east of the
Laramie range.

Another hot day is expected Monday as the ridge axis shifts closer
to our area. Many in the High Plains may already be in the 90s by 9-
10AM Monday with plentiful morning sunshine. The Nebraska panhandle
and far eastern Wyoming should manage a few degrees warmer Monday
compared to Sunday. Probabilities for 100+F temperatures are around
80% for Scottsbluff, 70% for Chadron, and 60% for Torrington.
Alliance, Wheatland, and Sidney have probabilities generally in the
10 to 50% range. The next shortwave trough riding over the top of
the ridge will approach Monday, pulling in slightly better moisture
into the 300 to 500-mb layer. Combined with some modest synoptic
lift associated with a few vort-maxes rotating over the ridge,
expect a little greater shower/storm coverage Monday afternoon.
Additionally, increased mid to high level cloud cover during the
afternoon hours may knock a few degrees off the afternoon highs
along and west of I-25. With forecast soundings showing deep
inverted-v soundings up to 500-mb and LCLs above the freezing level,
storms will again probably be mostly virga, with gusty winds,
lightning, and possibly a few hundredths of an inch of rain.

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
Issued at 424 AM MDT Sun Jun 23 2024


A ridge of high pressure over the western CONUS will persist over
the first portion of long term forecast. Dry and warm weather will
continue on Tuesday with temperatures running above normal. By
Wednesday afternoon and evening, PWAT values begin to rise as a
plume of early monsoonal moisture drifts north over the central
Rockies. Some surface moisture return is noted on the eastern plains
as well with dewpoints at or above 60 possible in the NE panhandle
per both latest ECMWF and GFS guidance. With moisture in place,
showers and thunderstorms will return on Wednesday evening. However,
any notable flow aloft remains well to the northwest of southeast
WY/western NE thus resulting in a low shear setup favoring multicell
storms and outflow-dominant clusters. By Thursday afternoon,
troughing in the west will translate eastward bringing faster
southwest flow aloft closer to our region. With surface moisture
remaining in place in upslope flow east of the Laramie range, a
better opportunity for organized convection may return on Thursday
afternoon and evening. Ensemble guidance is rather tightly clustered
still on Friday, showing a frontal system moving through early in
the day resulting in lower temperatures across Wyoming and western
Nebraska. Precipitation chances look highest early in the day as the
front passes with a generally dry and breezy afternoon and overnight
behind the front. Ensemble guidance continues to remain closely
grouped into early next weekend showing a dry, post-frontal westerly
flow regime with moderating temperatures. Overall, forecast
confidence is high throughout the long term with the best
opportunity for precipitation coming on both Wednesday and Thursday
afternoons.

&&

.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
-- Changed Discussion --
Issued at 1103 AM MDT Sun Jun 23 2024

Pretty similar conditions expected this afternoon compared to
yesterday. Could see a few showers around KCYS and KLAR this
afternoon as CU has begun to pop around both airports. Nothing
too serious though. Maybe even a few rumbles of thunder for
KCYS. Decreasing clouds after 23Z or so at both KCYS and KLAR.
Sunny skies and dry elsewhere.
-- End Changed Discussion --

&&

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

&&

$$

SHORT TERM...MN
LONG TERM...MAC
AVIATION...GCC