377
FXUS65 KRIW 111602
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
1002 AM MDT Sat May 11 2024

.KEY MESSAGES...

- A nice start to the weekend with mild temperatures and only
  isolated convection.

- Warmer tomorrow with a better chance of showers and
  thunderstorms, but most places should be dry most of the day.

- Unsettled for much of next week with a few rounds of showers
  and storms. Details for timing and placement of heaviest
  precipitation remains uncertain.

&&

.DISCUSSION...
Issued at 321 AM MDT Sat May 11 2024

I apologize for the lateness of the discussion today. The northern
lights were absolutely stunning tonight, and this, along with the
quiet weather, lead to many of our meteorologists taking trips
outside to witness the best display of the aurora in many years.
Personally, it is the best I have seen, and I started my Weather
Service career in northern Alaska.

So, back to the weather. All in all, it looks like a nice start to
the weekend today with mild temperatures and light wind. The only
small fly in the ointment is the small chance (less than 1 in 5) of
a stray shower or thunderstorm over the mountains, courtesy of a bit
of moisture and a weak upslope flow around an upper level low over
Colorado. Nevertheless, a nice start to the weekend.

Things do turn a bit more active on Sunday, as a shortwave
drops down out of Montana and brings a better chance of
afternoon convection to most of the area except the far west.
The best moisture and forcing is found from roughly the Bighorn
Range and east, and these are where the higher POPs (1 in 3) are
found versus further west, where the chances are 1 in 4 at
best. However, even in areas that get a shower or storm, it will
be a small portion of the day so most of the day looks rain
free even in these locations.

We then enter a more active pattern to start the work week. The
ridge will be pushed east and replaced by an approaching Pacific
trough and cold front. Models have come into somewhat better
agreement with some details with this system, with the best chance
of showers and storms across northern Wyoming, where there will be
some helping jet energy to enhance upper level divergence. POPs were
tapered up to a 3 in 5 chance across the far north and a less
than a 1 in 5 chance across the south. Southerly flow ahead of
the front will bring warm temperatures Sunday and Monday, with
some locations possibly reaching the 80 degree mark.

Uncertainty increases starting on Tuesday and extending through the
work week. A series of systems will cross the area and bring
chances of showers and thunderstorms, but no major systems are
expected. We do have high confidence in temperatures falling
behind the front starting Tuesday, and especially Wednesday when
many locations could be 15 degrees below normal. Temperatures
then moderate toward the end of the week. So, to sum up the
latter part of the forecast period, we have high confidence in
an unsettled pattern with variable temperatures (greater than a
4 in 5 chance), but details in the timing and placement of
precipitation remains rather low.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1000 AM MDT Sat May 11 2024

VFR conditions, with SKC skies, and light winds will begin the
TAF period. High clouds will stream over the area from the north
through the afternoon, as CU develops over southern portions of
the forecast area, as well as the Bighorn Mountains. There
remains a 10% chance of isolated showers and thunderstorms for
these areas and have left VCSH/VCTS mentions out of the
forecast, as they are not expected to pose any direct impact to
any terminal. The one exception could by gusty outflow winds
hitting KBPI/KPNA late this afternoon toward 00Z. Winds will
remain light overnight, with mostly clear skies.

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

&&

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

&&

$$

DISCUSSION...Hattings
AVIATION...LaVoie