Riverton, Wyoming 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

609
FXUS65 KRIW 142014
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
214 PM 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 (20% 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 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.

&&

.UPDATE...
Issued at 212 PM MDT Wed May 14 2025

A few scattered to broken low cloud decks developed this morning,
but scattered out quickly, allowing for some diurnal heating and
convection to fire. Though instability is generally weak, there has
been enough to produce graupel and pea-size hail from stronger
storms across the Wind River Basin and Johnson County. Snow showers
have generally been confined to elevations above 8000 feet, but A
few lower elevation locations, including Pinedale, have seen some
brief snow showers thanks to evaporative cooling with precipitation.

The shower and thunderstorm activity will continue through the rest
of the evening and overnight. Additional rainfall/SWE amounts will
be minimal, generally less than 0.25" (2 to 3 inches of snow for
elevations above 8000 feet). Locations that see several rounds of
heavier showers and thunderstorms occur could see locally higher
amounts.

&&

.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 /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 1149 AM MDT Wed May 14 2025

Scattered showers and thunderstorms are beginning to develop across
the entire area and are expected to increase in coverage as the
afternoon progresses. Because of the scattered to widespread nature
of convection, there is a good amount of uncertainty in exact
timing of direct impacts to terminals and this is reflected in
PROB30 groups at each terminal. For direct impacts to a
terminal, anticipate MVFR visibilities in heavier
thunderstorms. Shower and thunderstorm chances decrease between
00Z and sunset (approximately 03Z).

Once convection diminishes, there is a 40% chance or less of MVFR
ceilings at all terminals except KCOD and KJAC where there is an 80%
chance of MVFR ceilings. This 40% chance or less is reflected
in a lower SCT ceiling. Overnight light rain is possible at all
terminals except KRKS and KWRL with little to no flight
reductions accompanying the light rain, however, brief periods
of MVFR cannot be ruled out if heavier rain occurs.

&&

.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.

&&

$$

UPDATE...Hensley
DISCUSSION...Hattings
AVIATION...Gerhardt