Hanna, Wyoming Weather Forecast Discussion

239
FXUS65 KCYS 212355
AFDCYS
Area Forecast Discussion
National Weather Service Cheyenne WY
555 PM MDT Sun Sep 21 2025
.KEY MESSAGES...
- Breezy conditions and overspreading precipitation continue
  into Monday as a Pacific system causes widespread rain and
  cooler temperatures to start the week.
- A cold front and weather disturbance will bring cooler and
  wetter weather for Tuesday, before a ridge aloft produces
  drier and warmer weather for Wednesday into the weekend.
&&
.SHORT TERM /THROUGH TUESDAY/...
Issued at 212 PM MDT Sun Sep 21 2025
Showers and storms have been a little more aggressive and
eastward moving than anticipated, and the forecast has been
updated accordingly. Expectation is that this will continue
through this afternoon, with the regional showers and storms
weakening later tonight but lingering at least through the
evening hours. The approaching Pacific trough and cold front are
expected to make their presence known tomorrow with widespread
precipitation and gusty winds. Precipitable water values of
0.5-1.0 inch are expected with this system, around 150-200% of
normal for this time of year. This should allow for overall
rainfall totals starting Monday and continuing just beyond the
short term into Tuesday of 0.5-1.0 inch for the CWA, highest
along the Snowy and Laramie Ranges. On the note of the Snowy
Range, 700mb temperatures continue to descend to around 0 to -1
C as this front makes its way through. With overall QPF values
over an inch for the Snowy Range and the expected cold, snow
levels should drop to around 9k feet Monday into Tuesday.
Forecast currently calls for notable mountain snow for this
range, with overall totals around 6-7 inches in the high terrain
and the peaks nearing 10 inches. This is nearing advisory level
criteria, but being the first system of the year and
temperatures having been as warm as they have been, overall
accumulations will likely be lower than this. Therefore have
held off on issuing an advisory for the snowy range, but we`ll
continue to keep an eye on the range over the next update or two
in case amounts increase or confidence in accumulations sticking
rises.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
Issued at 212 PM MDT Sun Sep 21 2025
Tuesday...The shortwave trough aloft moves across our counties,
producing scattered to numerous showers and thunderstorms, along
with cooler temperatures due to cloud cover and precipitation
coverage.
Wednesday...A warming and drying trend begins as a high amplitude
ridge aloft builds across Utah and western Wyoming.
Thursday...Dry weather continues with a warming trend as the ridge
aloft transitions over eastern Wyoming.
Friday...Mild and dry weather continues as the ridge aloft moves
eastward over the western high plains, and the low and mid levels
remain relatively dry.
Saturday...Although a shortwave trough aloft moves across the Four
Corners states, clouds and precipitation associated with the trough
will remain to the south of our counties. 700 mb temperatures
suggest little change in temperatures.
Sunday...Moist southerly flow aloft develops ahead of the shortwave
trough aloft over Arizona. There may be enough of an increase in low
and mid level moisture to spark isolated afternoon showers and
thunderstorms over the Snowy Range and southern Laramie Valley. High
temperatures remain similar to Saturday.
&&
.AVIATION /00Z TAFS THROUGH 00Z TUESDAY/...
Issued at 555 PM MDT Sun Sep 21 2025
Isolated showers and thunderstorms have been rolling through the CWA
this afternoon, affecting KLAR, KCYS, and KSNY. Additional storms
are moving into and across Carbon County now, impacting KRWL with
gusty winds of up to 35 knots. Expect these storms to move east this
evening possibly affecting KLAR and KCYS. As a result, if any of
these storms impact a TAF site, like KRWL, expect gusty and erratic
winds of up to 35 knots with CIGs in the 5 - 10K feet range.
Elsewhere, expect breezy conditions of 10 - 15 knots, gusting up to
25 knots, for the remainder of the terminals across WY into this
evening. Another breezy day is in store for all terminals across the
CWA on Monday with more showers and thunderstorms in the
afternoon.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...None.
NE...None.
&&
$$
SHORT TERM...CG
LONG TERM...RUBIN
AVIATION...RZ

NWS CYS Office Area Forecast Discussion