164
FXUS65 KRIW 181016
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
416 AM MDT Fri Oct 18 2024

.KEY MESSAGES...

- Winter Weather Advisories remain in effect for several
  mountain ranges, along with Freeze Warnings for Friday night
  into Saturday morning.

- Temperatures are not expected to drop to freezing this
  morning. Any snow accumulation in the lower elevations will be
  isolated.

- It will remain cool on Saturday before it warms back up on
  Sunday. Seasonal to slightly above normal temperatures will
  then be in place well into next week, with little in the way
  of precipitation once again.

&&

.DISCUSSION...
Issued at 153 AM MDT Fri Oct 18 2024

Light to moderate rain showers continue across the CWA early this
morning. Most of these showers will become confined to areas east of
the Divide as a minor shortwave over south-central portions rotates
northward. A midlevel low will track over Unita County after 06Z and
reach the Flaming Gorge Reservoir by 12Z this morning. This will
bring an additional round of showers to southern portions, where a
tenth to a quarter of an inch of precipitation could occur through
the rest of the morning. Additionally, easterly winds with gusts up
to 45 mph will occur due to the tightening pressure gradient from
the midlevel low. Gusty north to northeast winds will also continue
east of the Divide through the rest of the morning, with the
stronger winds occurring in the Bighorn Basin. These winds will
gradually decrease by early afternoon. Model trends have backed away
from temperatures reaching and/or dropping below freezing sometime
this morning and staying in the 33-37F range. Thus, if any change
over to snow does occur, accumulations will stay in the grassy areas
and likely melt on contact on roadways. Lower elevation areas above
6000 ft have the better chances for snow, like Beaver Rim (Fremont
County) and Meeteetse (south of Cody). High temperatures will not be
as cold today either. Much of the area will be in the 40s, with a
few locations rising into the lower 50s.

Precipitation will begin to end from the northwest to southeast
through the afternoon and end across the CWA between 00Z and 06Z
Saturday. A Freeze Watch remains in effect for Friday night with
overnight lows in the 20s expected. Some of the colder spots in
Yellowstone NP, the Jackson Valley and the northern end of the Upper
Green River Basin will have lows in the teens.

Conditions will by dry and seasonal across the forecast area, with
highs in the 50s. A few locations across northern WY could reach 60
degrees. Conditions will remain dry Sunday and Monday, as
temperatures continue to moderate. A somewhat zonal flow pattern
will be in place by Tuesday, with a ridge rebuilding over the
western CONUS Wednesday. This will allow for temperatures to rise
slightly above normal for areas east of the Divide. Models are
having trouble depicting a storm dropping south from
Alberta/Saskatchewan Tuesday and tracking over the Northern Plains
and Upper Midwest. The associated cold front looks to clip northern
portions of the state. There is no moisture associated with it
either, so the main impact could be gusty winds at Buffalo.
Something to keep an eye on through the weekend.

&&

.AVIATION /12Z TAFS THROUGH 12Z SATURDAY/...
Issued at 413 AM MDT Fri Oct 18 2024

IFR to MVFR ceilings at many locations with the first surge
post frontal with rain on station and some restrictions to
visibility. IFR to LIFR ceilings and visibility west of the
Divide through mid to late morning 15-17Z, before improving
through the afternoon as snow tapers off west to east. A bit
later east of the Divide lingering at KLND with the heaviest
impacts due to upslope conditions with snow. Lower visibility
to IFR with possible ceilings to LIFR through evening around
00Z before improving there. Improving skies after 00-01Z for all
locations into the overnight hours into Saturday morning. Some
TAF sites may see fog after 06Z Saturday if the sky can clear
rapidly but not enough confidence to pinpoint at this time.

Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for
the latest information on smoke, icing, and turbulence

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
Freeze Warning from 11 PM this evening to 10 AM MDT Saturday
for WYZ003>006-010-011-016>018-020-028>030.

Winter Weather Advisory until 6 PM MDT this evening for
WYZ007>009-014-015.

Winter Weather Advisory until 6 PM MDT this evening for WYZ019.

&&

$$

DISCUSSION...LaVoie
AVIATION...Hattings