160
FXUS65 KRIW 011708
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
1108 AM MDT Tue Oct 1 2024

.KEY MESSAGES...

- Turning warmer today with critical fire weather across
  portions of central and southern Wyoming.

- An approaching cold front will bring more widespread elevated
  to critical fire weather on Wednesday.

- The pattern of above normal temperatures and below normal
  precipitation will continue into next week.

&&

.DISCUSSION...
Issued at 215 AM MDT Tue Oct 1 2024

The overall pattern will not change for the next several days.
Things remain fairly quiet this morning. This has been the
coolest night, we have had in a while. A few spots East of the
Divide has already dropped down into the 20s, and more likely
will since cooling now lasts until around 7 am.

Temperatures will recover more today as we will have another
day of nearly full sunshine and flow turning back to the
southwest. And this will bring another familiar problem over the
past few days, more concerns about fire weather. Flow is still
at a decent pace across the area, with 700 millibar winds
maximized across southern Wyoming. Dew points remain very low,
falling into the teens and even single digits. With the favored
southwest flow, will will upgrade the Fire Weather Watches to
Red Flag Warnings this morning. The humidity is a slam dunk, the
limiting factor will be wind, which is borderline in some
locations. But given how dry it has been with the lack of rain
and above normal temperatures, we decided to issue.

Wind should decrease tonight. And this could lead to patchy
frost and possible freezes tonight. No additional highlights
here through. We will wait until the current freeze warnings
expire, as if some achieve it tonight, we will not need them.

Fire concerns will likely increase Wednesday as another
shortwave and dry cold front drop southward toward the area.
This will tighten up the pressure gradient ahead of it,
increasing the wind across portions of the area. If there is a
small silver lining, it is that humidity will be somewhat
higher. There is still a greater than 4 out of 5 chance of
falling below critical levels though. With the increased wind,
we have extended the Red Flag Warnings through Wednesday
afternoon. We have also issued a Fire Weather Watch for much of
Fremont and Sublette Counties and I could see more counties
included, but not enough confidence to issue at this time. The
southwest, downsloping flow ahead of the front will also raise
temperatures 5 to 10 degrees, with warmer spots approaching 80
degrees again.

The front then moves through the area Wednesday night into
Thursday morning. The result will be temperatures dropping
around 5 to 10 degrees. But more importantly, dew points looks a
little higher behind the front. With less wind, Thursday will be
a cooler day with less wind and as a result an easing of fire
weather concerns. Then Friday into the weekend look the same
with continued flat ridging across the area, with above normal
temperatures and continued fire weather concerns with a gusty
wind continuing. At this point, Saturday looks like the most
concerning in the longer range with another weak shortwave and
weak cold front moving through the area. There is still a spread
in guidance so details are still uncertain. Most guidance in the
long range also continues to hold the ridging over the western
United States, keeping above normal temperatures around along
with little to chance of any decent precipitation.

&&

.AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 1105 AM MDT Tue Oct 1 2024

Northwest mid-level flow will become more westerly by the end of
the day and into Wednesday, with the surface pressure gradient
driving gusty southwest to west winds this afternoon and
evening. The strongest winds will be in the eastern foothills of
the mountains and from KRKS to KCPR. Some high-level clouds are
skirting northern WY today, but skies should become mostly
clear by midnight. Smoke continues to be an issue for some areas
as well, reducing visibilities to 5 or 6 SM. Winds will remain
breezy in some areas past midnight tonight before decreasing
somewhat. With mostly clear skies on Wednesday, west to
southwest winds will increase by late morning and be gusty
(15-25 kts) during the afternoon. A weak cool front will again
push from MT into northern WY early Wednesday afternoon, moving
southward through the evening into central WY. Some increasing
mid-level clouds (and possibly low-level clouds around KBYG) will
move into north-central WY Wednesday evening, and westerly
winds will remain gusty into the evening across southern WY as
well. VFR conditions are generally expected, though brief MVFR
may occur due to smoke in the early morning hours.

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 215 AM MDT Tue Oct 1 2024

Flow will turn back to the southwest today along with
temperatures warming again. Relative humidity will remain very
low, falling into the single digits across much of the area.
Gusty wind will continue across southern Wyoming, especially
from Rock Springs to Casper and the central mountains. With
that, Red FLag Warnings have been issued for these locations.
Elsewhere, wind should remain light to moderate. Mixing and
smoke dispersal will range from fair in the north to very good
in the south.

A dry cold front will approach the area on Wednesday. The front
will increase wind across much of central and southern Wyoming
with gusts over 30 mph possible across much of this area. With
humidity remaining under 15 percent, Red Flag Warnings were
issued continued through Wednesday and Fire Weather Watches
were issued in portions of central Wyoming.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning until 8 PM MDT Wednesday for WYZ279-280-285-
288-289-300.

Fire Weather Watch from Wednesday morning through Wednesday
evening for WYZ278-283.

Air Quality Alert until 1 PM MDT Wednesday for WYZ016.

&&

$$

DISCUSSION...Hattings
AVIATION...McDonald
FIRE WEATHER...Hattings