423
FXUS65 KRIW 161030
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
430 AM MDT Fri Aug 16 2024

.KEY MESSAGES...

- Elevated to critical fire weather like today for portions of
  central and southern Wyoming.

- A better chance of thunderstorms returns to southwestern
  Wyoming tomorrow afternoon.

- Near to above normal temperatures are expected from Sunday
  through much of next week with daily chances of showers and
  storms.

&&

.DISCUSSION...
Issued at 303 AM MDT Fri Aug 16 2024

As expected, a few showers and thunderstorms have lingered
through the nighttime hours. We still have a few around 3 am,
but they are becoming less numerous and weakening. These should
be gone around or shortly after sunrise. All in all, this looks
to be the driest day of the forecast period as ridging builds
northward across the area and drier air punches in from the
southwest. A weak shortwave topping the ridge may have just
enough moisture for isolated storms this afternoon across the
northern third of the area, but the chance is less than 1 out of
5 in any location. Any storms should end around sunset with dry
weather the rest of the night. With the ridging, temperatures
will climb to above normal levels again.

The main concern will be elevated to critical fire weather. The
nearby shortwave will create just enough wind to reach critical
criteria across southern Wyoming. With humidity expected to drop
under 15 percent as the atmosphere mixes out, we have upgraded
the watches to Red Flag Warnings for Sweetwater County as well
as the Green and Rattlesnake Mountains. We will issue some fire
weather statements for surrounding areas, where either wind or
humidity should not quite reach criteria.

The break in the convection will be brief though as a surge of
moisture moves into the west around the back side of the ridge.
Precipitable waters may climb to 150 percent of normal. It will
take some time though, so most of Saturday looks dry. Any
convection Saturday or Saturday night would likely be confined
to southwestern Wyoming and areas West of the Divide since
downsloping flow should keep areas further north and east mainly
dry. This will be a hot day as well, with high temperatures
climbing into the 90s in many of the population centers (a
relative term in Wyoming to be sure) East of the Divide.

Sunday and Monday both look fairly active with a couple of
shortwaves passing nearby and precipitable water values around
150 percent of normal leading to a better coverage of showers
and thunderstorms. The pattern favors areas West of the Divide
with the higher chance, but all areas will have a possibility.
Somewhat drier air may then bring a lull for Tuesday. Beyond
that, there is more spread in the models so predicting which day
is wetter is very difficult. With the ridge holding through the
period, we have around a 4 in 5 confidence of temperatures
remaining near to above normal through the period.

&&

.AVIATION /12Z TAFS THROUGH 12Z SATURDAY/...
Issued at 425 AM MDT Fri Aug 16 2024

A few lingering showers are moving northeast across portions of the
area this morning. These will wane over the next couple of hours
leaving clearing skies. Convection this afternoon will be much more
limited, mainly impacting northern Wyoming. Confidence is not high
enough to mention at any terminals. Otherwise, VFR conditions are
expected, with a breezy afternoon wind across the southern half of
the area.

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

&&

.FIRE WEATHER...
Issued at 303 AM MDT Fri Aug 16 2024

A combination of humidity falling in the lower teens and winds
gusting to 30 mph will bring critical fire weather to portions
of Sweetwater, Fremont and Natrona Counties this afternoon.
Elevated fire weather is possible for other portions of southern
and central Wyoming. Elsewhere, wind should remain light to
moderate. Isolated thunderstorms will remain possible across
northern Wyoming. Mixing and smoke dispersal will be generally
good to excellent in the afternoon.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning from noon today to 8 PM MDT this evening for
WYZ279-289.

&&

$$

DISCUSSION...Hattings
AVIATION...Myers
FIRE WEATHER...Hattings