177 
FXUS65 KCYS 072356
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
556 PM MDT Fri Oct 7 2022

.SHORT TERM...(This evening through Saturday)
Issued at 121 PM MDT Fri Oct 7 2022

After a moist and foggy start to the morning, clouds have begun to 
clear out across the area. Chilly fall temperatures are expected 
this afternoon with highs in the 50s. Clear skies and calm winds 
overnight will lead to substantial radiational cooling with 
widespread lows in the low to mid 30s. This prompted the issuance of 
a Frost Advisory by the previous shift for areas east of the Laramie 
Range. Expanded the Frost Advisory to include valley locations as 
well, since temperatures may drop below freezing. Did not have 
enough confidence to go with a Hard Freeze Warning for these 
locations as some of the Hi-Res guidance suggest some cloud cover 
over the valleys which could limit how cold temperatures get.

Quiet weather is expected this weekend as the main upper-level 
trough axis pushes further off to the east, leaving the region in 
drier, northwesterly flow. As the trough moves east, this will allow 
slightly warmer 700 mb air to filter in. This will lead to 
temperatures gradually warming through the weekend. Temperatures on 
Saturday are expected to be about 10 degrees warmer than today, so 
high temperatures will be in the 60s across the CWA. Sunday will be 
even warmer, with some low 70s returning to parts of the CWA! 
Precipitation chances look almost non-existent over the weekend 
as dry air and clear skies look to dominate. Overall, a pleasant 
fall weekend is in store!

.LONG TERM...(Monday - Friday) 
Issued at 121 PM MDT Fri Oct 7 2022

A warm & dry start to the extended forecast period w/ 700 millibar
temperatures of +6 to +8 deg C supporting daytime highs in the 70s
for most areas along/east of I-25 through Tuesday. Increasing low-
level gradients are expected Monday night into early Tuesday ahead
of a strong cold front poised to blast across the CWA late Tuesday
afternoon or early evening. H7 CAG-CPR gradients climb to 50 to 55
meters by 12z Tuesday, with 700-800 millibar flow increasing to 40
to 45 knots across the southeast Wyoming wind corridors. Could see
a brief episode of high winds for Arlington & Bordeaux, as well as
the I-80 Summit area during this time period. A few showers should
spread across much of the CWA Tuesday night and early Wednesday w/
the passage of the aforementioned cold front. The GFS, ECM and GEM
all suggest H7 temperatures plunging to -2C or colder by Wednesday
morning, although the timing differs slightly among models. Cannot
entirely rule out a few snow flakes on Tuesday night if showers do
not stay out ahead of the front. Given more potential for clearing
on Wednesday night, could be a chance for more widespread freezing
temperatures on Thursday AM w/ the cold air mass in place. 

&&

.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 534 PM MDT Fri Oct 7 2022

TAFs will be tricky to fine tune this evening due to pesky low
CIGs and an eventual resurgence of FG/FZFG overnight. KCYS will
transition from MVFR to low-end VFR this evening before going to
becoming SKC after 6Z. KLAR will transition from VFR to MVFR
shortly after 6Z/7Z overnight, but FZFG will result in reduced VIS
and CIGs by 8Z. This will cause KLAR to transition to IFR/LIFR
through approximately 15Z/16Z Saturday before going to VFR. KRWL
is expected to be VFR through the forecast period. 

The NE Panhandle terminals will also be difficult to pinpoint the
exact timing of reduced VIS and CIGs, but at this time, KBFF and
KCDR look to be the most probable for a transition from VFR to
IFR/LIFR near 9Z/10Z with FG likely. KSNY/KAIA could see reduced
VIS, but it does not appear to have FG arrive at those terminals.
Will need to monitor in the event AMD are necessary overnight
before the 12Z TAF issuance. Please 

&&

.FIRE WEATHER...
Issued at 121 PM MDT Fri Oct 7 2022

Minimal fire weather concerns expected through the weekend due to 
moisture associated with a cold front that moved through Thursday 
night. Minimum RHs this weekend will fall into the low 20 percents, 
however, light winds and excellent humidity recoveries are expected 
overnight. Conditions further dry out Monday into Tuesday with 
minimum humidities falling into the upper teens and wind gusts up to 
20 kts.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...Frost Advisory from midnight tonight to 8 AM MDT Saturday for 
     WYZ101-102-105-107-108-113-115-118-119.

NE...Frost Advisory from midnight tonight to 8 AM MDT Saturday for 
     NEZ002-003-019>021-054-055-095-096.

&&

$$

SHORT TERM...SF
LONG TERM...CLH
AVIATION...BW
FIRE WEATHER...SF