Riverton, Wyoming 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

062
FXUS65 KRIW 141612
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
1012 AM MDT Wed May 14 2025

.KEY MESSAGES...

- Increasing chances for showers and thunderstorms through the
  afternoon, mainly along and east of the Divide. A few stronger
  storms are possible (10% chance), with gusty winds and small
  hail being the primary threats.

- Continued instability and active weather pattern with bring
  additional shower and thunderstorm chances (30 to 50%)
  Thursday and Friday afternoon.

- The pattern of near to below normal temperatures and above
  normal precipitation will continue into early next week with a
  more potent storm with chances for widespread significant
  precipitation looking more likely (60% chance) Saturday night
  through Monday.

&&

.DISCUSSION...
Issued at 313 AM MDT Wed May 14 2025

Things look to remain rather active over the next several days.
May is climatologically our wettest month, and this one is
certainly no exception. As I write this, most of the showers
have retreated to the northern portions of the state, with the
heaviest in Montana. An upper level low will cross the state
today, and bring more showers and thunderstorms. The most
numerous will be found across northern Wyoming, closer to the
upper level low. Strong storms do not look like likely, given
that temperatures will average 15 to 20 degrees cooler, limiting
instability a bit more. As for the highlights, we will keep the
Winter Weather Advisories up for now, but amounts look
borderline in a lot of areas, with at most a 1 in 2 chance of 6
inches or more over the higher peaks. As for flooding potential,
it is still there. However, with the cooler temperatures snow
levels have lowered and additional run off from melting snowpack
will likely be limited. As for the Flood Advisory for Pacific
Creek, the level has dropped a bit. With additional rain
expected, we will keep the Advisory up for now. Much of the
northwestern portion of the forecast area has at least a 1 in 2
chance of a quarter inch of precipitation as the low passes,
although with precipitable water values lower than yesterday,
rainfall rates would likely be less.

Thursday also looks active as a shortwave drops in from the
northwest with another round of showers and thunderstorms likely.
Again, strong thunderstorms are not expected as cool temperatures
and cloud cover should limit instability. Friday should be less
active as shortwave ridging moves across the state. There will still
be a few showers and thunderstorms around, but most locations
will likely be dry most of the time. With more sunshine,
temperatures will begin to moderate closer to seasonal normals.

Things then turn more active again this weekend, as another
upper level low moves onshore over the Pacific Northwest and
moves eastward into the Rockies for Sunday and the start of next
week. If you are looking to do something this weekend, Saturday
definitely looks like the drier of the two days, especially the
further east you go. Things then look potentially active for
Sunday and into early next week as the low moves eastward and
across the Rockies. However, upper level lows are notoriously
fickle with movement, especially this far out. So, although it
looks like some additional showers and thunderstorms are likely
Sunday into Monday, details about precipitation amounts and
placement of the heaviest precipitation remains very much in
flux. And with the persistent mean trough position, temperatures
should average near to above normal through the period.

&&

.AVIATION /12Z TAFS THROUGH 12Z THURSDAY/...
Issued at 430 AM MDT Wed May 14 2025

VFR ceilings in place this morning with isolated locations
having LIFR ceilings. Those locations are expected to return to
VFR NLT 16Z. Widely scattered showers continue moving northward
over the Bighorns and Johnson/Natrona counties from the east
side of an upper level low currently situated over ID/MT. Rain
showers and thunderstorms will redevelop across the CWA by 18Z
as the low tracks eastward. Showers and thunderstorms will be
possible for most terminals through the afternoon, with the
thunderstorm threat ending by 01Z. Showers will continue through
the rest of the TAF period from western portions and along a
rough KCOD-KRIW-KCPR line as the flow aloft turns northwesterly
as the low exits out of the forecast area. MVFR/marginal VFR
conditions are expected with any shower/thunderstorm. Mountain
obscurations will occur throughout the forecast period.

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

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 6 PM MDT this evening for WYZ002.

Winter Weather Advisory until 11 PM MDT this evening for
WYZ008-009.

&&

$$

DISCUSSION...Hattings
AVIATION...LaVoie/Lowe