993
FXUS65 KRIW 190347
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
947 PM MDT Wed Jun 18 2025

.KEY MESSAGES...

- Dry conditions and relatively light winds (gusts up to 20 mph)
  continue through the rest of the day today.

- Critical fire weather conditions develop Thursday and continue
  through Saturday as a result of hot, dry, and windy conditions
  across the region. Winds could gust 40 to 50+ mph Friday and
  Saturday.

- Very poor overnight RH recoveries, particularly across
  southwest WY, will exacerbate critical fire weather conditions
  through Saturday.

- A cold front bring some relief to the warm temperatures
  Saturday to the west, and by Sunday to other parts of the
  region. Some precipitation is possible as well, but there are
  still a lot of uncertainties with amounts and timing.

&&

.UPDATE...
Issued at 140 PM MDT Wed Jun 18 2025

High pressure is fully embedding itself over the region for the next
few days. Seasonable temperatures today will make way to much above
normal temperatures tomorrow (Thursday). The forecast remains on
track, with few changes. Temperatures remain on track to reach the
mid 90s on Thursday. This is not expected to break any records as
records are near 100 for most locations. Critical Fire Weather
conditions will continue to be the primary focus through Saturday.
Southwest winds will begin to increase Thursday with gusts 25 to 35
mph during the afternoon, and even more so Friday afternoon (gusts
30 to 40 mph). The gusty winds combined with the hot and dry
conditions will be the primary driver of the critical fire weather
concerns. The other concern is very poor overnight RH recoveries,
particularly across southwest WY Thursday night and Friday night.
RHs may only recover from single digits during the day to the mid to
upper teens overnight. Some locations may not see RHs climb above
critical thresholds.

&&

.DISCUSSION...
Issued at 118 AM MDT Wed Jun 18 2025

A strong ridge will build over the Northern and Central Rockies
today, beginning a warming trend and drier conditions through the
rest of the week. Wednesday will be the quietest day, with seasonal
temperatures and mostly clear skies. Fire weather conditions will be
elevated and mainly confined to Sweetwater County, where relative
humidity (RH) values will be below 15%. Wind gusts will be less than
25 mph across the CWA this afternoon.

Elevated to critical fire weather conditions will be in place
Thursday, as temperatures rise into the 90s across much of the area.
This will be well above normal for this time of year and a few
records could be broken. RH values below 15 percent will be much
more widespread as well, spreading across southern and central
portions of the CWA. Southwest winds, with gusts of 25 to 35 mph,
will be fairly widespread, with the stronger winds occurring over
northwestern portions. This will be due to a shortwave moving over
the area. Similar conditions return Friday, with the stronger gusts
of 30 to 40 mph being more widespread across the south and Natrona
County. By Saturday, these conditions spread into the Bighorn Basin
and southern Johnson County. Wind gusts of 25 to 40 mph will be
widespread across the forecast area. This will be due to a digging
longwave trough with a closed low over the PACNW and a strong
(596dm) high center over the Ohio Valley. This will, in turn,
strengthen the pressure gradient over the Cowboy State and lead to
the higher winds. Burning of any kind is highly discouraged! Far
western portions will have some relief from the hot temperatures as
a cold front associated with the closed low will move over the area
late Friday night/early Saturday morning, resulting in high
temperatures in the 70s.

The front will become stationary over western portions Sunday,
however temperatures will still be 10 to 15 degrees cooler as
the ridge shifts eastward and the longwave trough having a
greater influence over the region. Precipitation chances are
still progged to remain over northern portions likely due to
most of the available moisture being around the closed low.
Needless to say, fire weather conditions will not be as
extensive and be confined over southern portions. The below
normal temperatures look to continue into Monday as the longwave
trough remains in place across the Intermountain West. This
will be a nice reprieve for this time of year, when we can see
record highs and heat waves in mid to late June. The next chance
for widespread precipitation could arrive on Tuesday.

&&

.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 945 PM MDT Wed Jun 18 2025

VFR conditions expected throughout the entire period for all TAF
sites. Clear skies and light winds overnight under a weak
inversion. Increasing winds after 17-19Z with daytime heating
and stronger mixing to the surface. 25-30kt gusts west of the
Divide to go along with RIW, with all other sites slightly lower
gusts up to 18kts and highest at RKS up to 30kts. Winds
decrease after around 02Z towards sunset with radiational
cooling as the scattered upper level clouds clear out into the
overnight hours into Friday morning. Otherwise, possible
thunderstorm chances for further north around COD between
21-00Z. Although, confidence is not as high (20-30%), a PROB30
group will be carried during that time.


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

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

UPDATE...Hensley
DISCUSSION...LaVoie
AVIATION...Lowe