989
FXUS65 KRIW 111716
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
1116 AM MDT Sun Aug 11 2024

.KEY MESSAGES...

- Showers and storms will be more isolated today and largely
  confined to northern Wyoming.

- More widespread showers and thunderstorms are likely from
  Monday through Wednesday.

- Somewhat drier and warmer from Thursday into Friday.

&&

.DISCUSSION...
Issued at 325 AM MDT Sun Aug 11 2024

We are currently having another night of nocturnal convection
as a shortwave moves across the area. Current radar shows a
couple of storms capable of small hail, given the low wet bulb
zero levels. But nothing severe is expected. And, with the fast
movement of the storms, the chance of flooding remains very
minimal.

There should be somewhat of a lull in the activity today as
shortwave ridging moves across the area and drier air moves in from
the west. Most models how precipitable water values falling anywhere
from 20 to 30 percent today from Saturday`s values. Satellite
imagery shows drier air moving in now with convection ending to the
west. As a result, most areas should end up with a rain free today
today. Any showers and storms today should be confined to northern
Wyoming, with the best coverage in Johnson County where moisture
will remain somewhat deeper. But even here, the chance is only
around 2 out of 5. One other thing today is some gusty breezes will
develop across southern Wyoming. With humidity falling into the
teens, elevated fire weather is possible. There has been some
moisture lately, so we were on the fence about this though. So,
we will issue a statement for elevated fire weather for
Sweetwater and southern Lincoln Counties for this afternoon.

The lull in the convection will be short, however. Some showers
may move back into southwestern Wyoming later Sunday night, but
most should hold off until Monday. For Monday, the deepest
moisture will be found West of the Divide with a good coverage
of showers and thunderstorms expected as precipitable water
values surge back toward an inch in some locations. Chances
taper further to the north and west as moisture will be slower
to return to this area. Chances look more widespread across the
area for Tuesday as deeper moisture spreads across the area. And
by Wednesday, somewhat drier air the moves into the west, and
this shifts the best chance of showers and storms to areas East
of the Divide.

Coverage of showers and storms should begin to decrease again
Thursday and especially Friday and Saturday as ridging builds back
over the area and most models show much drier air moving into the
area, with precipitable water values falling to below normal levels.
There will still be a few showers and storms around each day, but
coverage will be limited to at most a 1 out of 3 chance and confined
mainly to in and near the mountains. Temperatures should remain near
to slightly below normal through Wednesday, then slowly climbing
again starting Thursday as ridging builds northward.

&&

.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 1115 AM MDT Sun Aug 11 2024

VFR conditions prevail through the TAF period. No showers or
thunderstorms are expected to impact any terminals this afternoon. A
few may develop over the mountains, but should be very isolated and
remain away from any sites. The closest would be for KCOD, but
chances remain under 20% through this evening. Afternoon mixing
brings gusts 15 to 30 knots for some sites, which decrease after
sunset this evening.

Models are showing rain showers moving into Wyoming, from the west,
after 09Z/Mon. There is model disagreement on exact timings and
placements, so confidence remains low on the details. Have included
PROB30 groups in many TAFs where these chances occur. Chances for
showers and thunderstorms increases after the TAF period, for Monday
afternoon.

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 325 AM MDT Sun Aug 11 2024

A combination of humidity falling into the teens and a gusty
westerly breeze will bring elevated fire weather to portions of
Sweetwater and southern Lincoln Counties today. Elsewhere,
although there will be a gusty breeze at times, relative
humidity will remain above critical levels. Showers and
thunderstorms will be more isolated today and confined mainly to
northern Wyoming. Mixing and smoke dispersal will be generally
good to excellent in the afternoon. More widespread showers and
thunderstorms return to the west tomorrow and spread across most
of the area for Tuesday.

&&

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

&&

$$

DISCUSSION...Hattings
AVIATION...Wittmann
FIRE WEATHER...Hattings