152
FXUS65 KRIW 251948
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
148 PM MDT Wed Sep 25 2024

.KEY MESSAGES...

- Three or four clouds possible during the next 24 hours.

- Red Flag conditions return Thursday, with very low humidity
  and gusty winds.

- A cold front may bring a sharp 20 to 30 degree temperature
  decline between Sunday and Monday, but no precipitation is
  expected with this front.

&&

.DISCUSSION...
Issued at 118 PM MDT Wed Sep 25 2024

A strong late-season H5 ridge remains dominant across the Four
Corners and eastern Rockies, and is keeping skies absolutely
clear today. This is also bringing temperatures well above
normal, reaching the upper 80s and lower 90s. Tomorrow will see
much of the same, with nearly clear skies and very warm
temperatures. The main difference tomorrow will be a weak "cold"
front moving across Montana into far north-central WY in the
afternoon. This will initially tighten the gradient across the
state, bringing gusty Wyoming winds. The unusually warm, dry,
and windy conditions have prompted a Red Flag Warning for
portions of the state (see Fire WEather discussion below). The
front will bring some brief north winds to Johnson County, but
the front does not have much of a southward push this time, so
overall effects will be minimal. Ridging continues over the
weekend, with well above normal temps and some increasing high
clouds.

Models have become a bit more aggressive with the next Canadian
system sweeping by, bringing a better cold front southward
Sunday night. Models are still differing on where the trailing
cold pool will dive southward, but it`s becoming more likely
that Monday will be much colder than the weekend. Current
ensemble forecast holds highs only in the 60s for most of the
state Monday. Sadly, the front still has minimal moisture to
work with, so no precipitation will accompany this front
either...

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 1047 AM MDT Wed Sep 25 2024

High pressure will keep skies clear and conditions VFR through the
TAF period. A weak trough will slide through the region Thursday,
but it will be a very dry system, with almost no moisture or cloud
cover as it passes by. Wind will be breezy this afternoon, as
well as Thursday afternoon as the trough approaches/moves
through.

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

&&

.FIRE WEATHER...
Issued at 118 PM MDT Wed Sep 25 2024

A Red Flag Warning has been issued for portions of the state
Thursday. A front crossing Montana on Thursday will bring brisk
southwest winds across the most prone areas of central and
southern WY. Humidity level 10 to 15 percent and wind gusts 25
to 35 mph will be common from RKS to CPR and across Johnson
County. Another concern is the front will push southward across
parts of Johnson County late in the afternoon, bringing an
abrupt wind shift from the north 20 to 25 mph late afternoon.
All winds will be decreasing at sunset. Winds will be much
lighter on Friday, and will remain below Warning Criteria.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning from noon to 7 PM MDT Thursday for WYZ279>281-
289.

&&

$$

DISCUSSION...Straub
AVIATION...Rowe
FIRE WEATHER...Straub