363
FXUS65 KRIW 121751
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
1151 AM MDT Fri Jul 12 2024

.KEY MESSAGES...

- Another day of hot temperatures.

- Isolated showers and thunderstorms may bring strong outflow winds
  gusting 50 to 60 mph this afternoon and evening.

- Elevated to near-critical fire weather conditions are expected
  through the weekend.

- Temperatures remain hot through the weekend, then cool slightly
  for early next week.

&&

.DISCUSSION...
Issued at 423 AM MDT Fri Jul 12 2024

Not a whole lot of change in the forecast today - it will be another
hot one. The strong ridge remains in place, now centered over
southern Utah. Highs will again peak into the upper 90s or lower
100s east of the Continental Divide and lower to mid 90s west.
That`s good for around 10 degrees above normal for this time of
year.

One potential difference today may be slightly increased coverage of
showers and thunderstorms this afternoon and evening. The best
chance for this activity will be across northern Wyoming owing to a
weak shortwave rotating through the flow. This area will also
benefit from higher moisture availability. Additionally, we expect
more cumulus buildup west of the Divide today, with an isolated
shower or storm possible (less than 10 percent for any one
location). In reality, most locations will remain dry across the
area, with much of the rain evaporating well before reaching
the ground given the dry boundary layer and correspondingly high
LCLs. As before, the main concern with any showers or storms
will be strong outflow wind gusting 50 to 60 mph.

With the potential for more convection and outflow, fire weather
concerns will be heightened today given the very warm and dry
(minimum humidity less than 10 percent) background environment.

The heat will continue through the weekend as the overall synoptic
pattern remains largely unchanged. Coverage of afternoon convection
will continue to trend up as monsoonal moisture is advected into
Wyoming. Again, however, the dry lower atmosphere will keep the
majority of the area rain-free with the main concern being wind
gusts.

By early next week the ridge may get flattened somewhat, which will
likely provide somewhat of a relief from the heat as well as
increased rain chances. Still, ensemble cluster guidance favors
continued anomalously high 500mb heights over the region through the
end of next week. This would keep temperatures on the warmer side
with precipitation chances limited to isolated diurnal convection.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 1145 AM MDT Fri Jul 12 2024

VFR conditions are at all TAF sites to start out the afternoon
under mostly clear skies, although slowly increasing smoke from
the west is starting to obscure the mountains/longer distances.
Breezy and gusty west-northwest winds are expected this
afternoon at most sites, with gusts around 20 kts. North winds
should continue in the Bighorn Basin. The best chances for late
afternoon and evening convection will be across northern WY,
primarily impacting KCOD from about 13/00-05Z. Gusty outflow
winds over 40 kts are possible at KCOD, as well as KWRL as
storms to the north push winds to the south. Feel that KCOD also
has the best shot for precipitation due to the storms, and thus
MVFR conditions could occur during the evening. Winds will
decrease around sunset generally and mid-level clouds will
linger across north-central WY into Saturday morning. Afternoon
cumulus fields should also diminish across the rest of the
forecast area overnight, though mid-level clouds will increase
from the SW to NE into western WY Saturday morning as moisture
from the Great Basin rotates into Wyoming. Breezy and gusty
winds should then occur again on Saturday with isolated showers
and thunderstorms returning to western WY and the mountain
areas as moisture in the mid-levels increases.

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 423 AM MDT Fri Jul 12 2024

Elevated to near-critical fire weather conditions are expected
through the weekend. Humidity will drop below 10 percent for much of
the area today. Wind will be the more limiting factor for a greater
risk, though any showers or thunderstorms in the area will have the
potential to produce outflow winds gusting 50 to 60 mph. Red
Flag Warnings were considered for some of the zones that have
fully cured fuels, but confidence on persistent, widespread
gusts over 25 mph is not high enough to warrant issuance at this
time.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
Heat Advisory until 10 PM MDT Sunday for WYZ004>006-010-011-
017-018-020.

&&

$$

DISCUSSION...Myers
AVIATION...McDonald
FIRE WEATHER...Myers