337
FXUS65 KRIW 140840
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
240 AM MDT Wed Aug 14 2024

.KEY MESSAGES...

- Another active day today with a decent coverage of showers and
  thunderstorms.

- Trending warmer and drier starting Thursday and especially
  Friday and Saturday as ridging builds northward into Wyoming.

- Elevated to possibly critical fire weather is possible Friday
  and Saturday.

&&

.DISCUSSION...
Issued at 236 AM MDT Wed Aug 14 2024

Other than a couple of stray showers, things are fairly quiet right
now. However, this day is looking much like the previous couple in
that we will have another day of showers and thunderstorms across
the area. Coverage may be a bit less than yesterday though.
Precipitable waters are shown to be about 10 to 20 percent less than
yesterday for example. All areas will still have a chance though.
And with the area in a marginal risk, some storms will have the
potential to be strong to marginally severe. The biggest threat
looks to be strong wind gusts, but small hail and brief heavy rain
are also possible. Storms may end earlier than yesterday in the west
than previous days though, as drier air begins to punch in from the
south and west.

And this will bring a change in the pattern somewhat. Ridging will
begin to build northward on Thursday and begin a transition to a
warmer and drier pattern. But notice the modifier, drier, not dry.
There will still be a few storms around on Thursday and Thursday
evening as a subtle shortwave moves across the area. However, the
forecast for Thursday evening is probably the absolute wettest it
will be. Our blend of models has been running a bit wet the
past several days and trend has been drier. My gut feeling is
that it will be drier than indicated. This even more so for
Friday, as precipitable waters fall to as much as 50 percent of
normal in some locations. I could see this day being completely
dry except for a stray shower or storm in the mountains.
Temperatures will also be on the rise, with some lower
elevations seeing high temperatures back into the 90s for Friday
and Saturday.

And this brings another question for Friday and Saturday, the
possibility of elevated to critical fire weather for these days. The
humidity looks like a good possibility to be there. However, at this
point the wind looks borderline as the ridge building northward but
be close enough to keep the wind moderate. Still time to watch it
though. If the winds trend up, we may need fire weather watches for
on or both of these afternoons in areas prone to southwest flow,
like Natrona and Sweetwater Counties.

The other question is convection starting Saturday. Just enough
moisture may creep northward for a few thunderstorms in
southwestern Wyoming on Saturday evening. A more defined
shortwave and deeper moisture returning should bring a better
chance of showers and storms for Sunday. Heading into early next
week, the pattern looks to have ridging over the area, keeping
temperatures somewhat above normal. There will be a couple of
chances of convection. However, guidance is more divergent with
timing of the shortwaves so details are difficult to resolve at
this time.

&&

.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 956 PM MDT Tue Aug 13 2024

Any lingering showers and thunderstorms will end over the next
couple of hours, leaving clearer skies overnight. The next round of
showers and thunderstorms will move in to western Wyoming around
16Z, once again becoming widespread after 18Z. Similar to previous
days, all terminals will carry a chance of thunderstorms for at
least part of the afternoon. Strong outflow wind gusts over 25
knots and brief heavy rainfall will be possible with this
activity. Convection will start to decrease 00-03Z and end by
06Z Thursday.

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 236 AM MDT Wed Aug 14 2024

No concerns today or tomorrow except for lightning strikes.
Concerns are mainly for Friday and Saturday as humidity drops
below 15 percent and an increasing southwest wind may bring
elevated to possibly critical fire weather to the southern half
of the area on Friday and/or Saturday afternoons.

&&

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

&&

$$

DISCUSSION...Gross
AVIATION...Myers
FIRE WEATHER...