138
FXUS65 KRIW 121959
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
159 PM MDT Wed Jun 12 2024

.KEY MESSAGES...

- Except for isolated monsoonal showers and thunderstorms
  Thursday, ridging will keep warm temperatures and relatively
  quiet weather around through the weekend.

- Increased river flows due to high elevation snowmelt continue
  but river stages have begun to trend down.

- Elevated fire weather conditions today, and will also return
  Saturday, thanks to dry, gusty winds.

- Cooler and slightly wetter pattern looks to move in late in
  the weekend to bring some relief to the region.

&&

.DISCUSSION...
Issued at 156 PM MDT Wed Jun 12 2024

There is not much to talk about out of the Blue Clear Skies today. A
few puffy, white fair weather cumulus clouds have developed in zonal
flow across the region. Instability is slightly increased along the
far southern portion of the CWA, where the Cu have a bit more
vertical development, being influenced by WSW flow pushing a bit of
monsoonal moisture into the area. There may be a brief shower or two
across far southern Sweetwater County this afternoon. Dewpoint
depressions are around 50 degrees, with inverted V soundings, so
gusty winds would be the main threat with any convection that does
develop. Any convection will generally be short-lived. Convective
chances increase Thursday afternoon, as the monsoonal moisture gets
a bit more of a push into the region, with a Pacific low pushing
northeastward into the base of the ridge. This will help to amplify
the ridge, but the added moisture may actually result in temps being
a degree or two cooler on Thursday. Still, upper 80s and low 90s
continue to be widespread across lower elevations. Best chances for
convection Thursday afternoon will be across the south and central
basins. Again, convection looks to be pretty limited (20 to 40%
chance) and biggest threat would again be gusty winds. Chances
continue into Friday evening, but will diminish overnight. Saturday
and Sunday, precip chances return to near zero as the monsoonal
forcing shifts eastward into southeast WY and western NE.

A Pacific trough begins to make its way on shore by late in the
weekend. ECMWF and GFS solutions both continue to prog 700mb temps
in the -6 to -8C range, which is a reassuring sign for those of us
who don`t like the heat. As this system moves into WY, temperatures
Monday and Tuesday look to be much cooler, with highs in the upper
60s to low 70s, rather than 80s and 90s. There does look to be some
moisture with this low as well, however, it looks to be isolated to
the northern half of the CWA and the trough does not look to dig
very far into our CWA, with most of the energy remaining over MT.
Thus, it is looking likely (70% chance) that high pressure will
return by mid-week and with it, the warm temperatures.

I do want to also discuss the fire and water impacts that we
continue to monitor this week. On the water side, rivers continue to
have high flows as we continue to melt out high-elevation snowpack.
Most of the snow has melted completely melted out per snotel
interrogation, and thus, we have noted river stages continuing to
trend downwards. On the fire side, gusty winds will continue to lead
to elevated to near-critical fire weather conditions. Today, low RHs
(12 to 20%) and gusty winds (25 to 35 mph) will continue across the
southwest and central basins with stronger winds up to 50mph across
the mountains. Winds will be slightly less Thursday and Friday
(except for gusty outflows). Then, ahead of the Pacific trough,
winds increase again Saturday, with critical or near-critical RHs.
Thus, elevated to near critical fire weather conditions will exist,
with greatest concern being today and Saturday.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 1122 AM MDT Wed Jun 12 2024

VFR conditions to prevail at all terminals through the forecast
period. The primary aviation hazard Wednesday afternoon and early
evening will be westerly surface wind 18G30kts. Mid-level winds mix
to the surface between 18Z-21Z and persist until decoupling around
03Z/Thursday. A few pockets of cumulus over the mountains Wednesday
afternoon with isolated convection coming off the Uinta Mountains
and hugging the UT/CO border south of KRKS. Given temperature-dew
point spreads, outflow gusts 40-50kts are likely in this region
through sunset.

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 156 PM MDT Wed Jun 12 2024

Gusty west to southwest winds gusting 25 to 35 mph will exist across
the southwest and central basins through the rest of the afternoon.
RHs will continue to meet critical thresholds (<15%) across much of
the same areas as well through the afternoon. RH recoveries are
expected to be good to excellent overnight, with winds decreasing to
light drainage flows toward sunset. Min RHs will again reach
critical thresholds Thursday and Friday, but winds will be much
lower with gusts across the favored southwest basins generally less
than 25 mph. Saturday, however, the winds increase again to 30 to 40
mph and RHs will remain critical, thus elevated to near critical
fire weather conditions are expected Saturday.

&&

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

&&

$$

DISCUSSION...Hensley
AVIATION...CNJ
FIRE WEATHER...Hensley