Rock Springs, Wyoming 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

010
FXUS65 KRIW 030335
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
935 PM MDT Wed Apr 2 2025

.KEY MESSAGES...

- Snow showers gradually diminish across northern Wyoming this
  evening. Periods of moderate to heavy snow and gusty winds
  could cause reduced visibilities.

- Additional snow accumulations between 1-3 inches for the
  Absaroka Mountains and up to 2 inches for Yellowstone
  National Park this evening.

- Scattered, less widespread snow showers are forecast again
  Thursday afternoon, with better chances east of the
  Continental Divide on Friday.

- Warmer and drier weather continues to look favorable this
  weekend into next week, although there is a chance for some
  weak weather systems next week.

&&

.UPDATE...
Issued at 1257 PM MDT Wed Apr 2 2025

A surface boundary situated near the Montana/Wyoming border (as
of 18Z) will push south over the next few hours. As the
boundary makes it`s southward move, a slight increase in
moisture will occur along and north of the boundary. This
mornings mostly sunny skies have allowed for sufficient daytime
heating to occur as well with afternoon SBCAPE values between
100-250 J/kg. This slight uptick in moisture, instability, and
the frontal boundary will support scattered convective snow
showers with some thunder potential across much of the area this
afternoon and early evening; however, chances (50-70%) for snow
showers are greatest across the northern half of Wyoming.

Portions of the eastern half of the CWA (the Bighorn Mountains,
Casper Mountain, and northern Johnson County) remain in a
Winter Weather Advisory through 6PM this evening. Enhanced
convergence along the boundary combined with daytime instability
will allow for periods of moderate to heavy snowfall rates
across the aforementioned locations and these areas could see
an additional 2-4 inches of snow now through 6PM.

The boundary stalls this evening and bisects the state roughly along
the Divide. Cloud cover is forecast to gradually dissipate
overnight along and south of the boundary. This will allow for
sufficient radiational cooling where clouds do clear,
potentially cooling temperatures a degree or two colder than
what is currently forecast. Otherwise, widely scattered
convective showers are forecast Thursday along and north of the
boundary with the help of a shortwave trough traversing the
region.

&&

.DISCUSSION...
Issued at 106 AM MDT Wed Apr 2 2025

Areas of snow showers moving across the Wind River Basin down
into eastern Sweetwater County ongoing through near sunrise
Wednesday morning. The NAMNest is handling this pretty well,
although other HiRes models not too far off having it dissipate
by this timeframe. Otherwise, the near stationary boundary to
the north will bring in another round of snow showers out of
Montana along the shortwave skirting around the main upper level
trough dipping to the south of the CWA. By early afternoon, the
Bighorns and northern Johnson County will see continuous snow
showers. Additional accumulations of higher confidence up to 4
to 8 inches (70-80%) for the Bighorns and 1 to 3 inches for
northern Johnson (50-60%). As winds increase through the
afternoon with the stronger gradient from the aforementioned
surface boundary, expect north to northwesterly gusts up to 25
to 35 mph that will limit visibility for these stretches of
interstate out of Buffalo. Mid to late afternoon, the highest
snow rates across Casper Mountain as the boundary sage south,
east of the Bighorns, also coupled with the stronger winds.
Elsewhere, some sporadic snow showers across the Absarokas and
Yellowstone, and more organized through the Wind River Basin. By
4-5PM, expect a subtle low to push a rain/snow mix through
about sunset before lingering as snow into the late evening
hours as it pushes southeast into Sweetwater County once again.
Regardless, the showers will dissipate towards midnight
lingering for Yellowstone by sunrise Thursday morning.

With the lingering surface boundary near the Montana state line,
another round of developing showers by mid afternoon, mainly
across the northern parts of the CWA. With a bit stronger
daytime heating, some instability off the Absarokas into the
western Bighorn Basin could see some isolated thunder chances
with 100-200 J/kg expected. This is where the stronger of the
PVA anomalies will be from the more elongated upper level
trough progressing a bit further east. Coverage a bit more
limited, mainly driven by daytime heating with more limited
accumulations expected for the higher terrain. With the upper
trough continues eastward dipped well to the south, more limited
coverage for eastern counties for any shower activity Friday
afternoon.

Overnight Friday into early Saturday morning, expect the main
finger of the PFJ finally eject the upper trough to the east of
the CWA allowing for the cold front to drop southeastward into
the high plains. This will give way to the more seasonable and
slightly cooler Saturday afternoon high temperatures with
improved conditions expected. Strong ridging builds into the CWA
from the west with increasing convergence aloft. The PFJ
remains well north and eastward aiding in dry weather into next
week, despite the more meridional upper level pattern. This
ridge will set in place through about mid next week giving way
to a warming trend, resulting in above average temperatures. A
couple shortwaves look to pass to the north with the southward
moving PFJ but impacts look to be limited with minor
precipitation chances for northern zones Tuesday through
Thursday. Otherwise, long term outlooks trend towards stronger
ridging, and dryer/warmer than average conditions expected
heading into the middle of the month.

&&

.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 915 PM MDT Wed Apr 2 2025

Shower activity continues to wane, with only a few light showers
in the vicinity of KCOD and KWRL. These should be done by 06Z,
so will not continue VCSH in those TAFs for tonight. VFR
conditions remain for the remaining sites overnight into the
day Thursday, with mainly high cirrus through the day. With the
remnant front across far northern Wyoming, some shower activity
is expected to redevelop late in the afternoon, with possible
impacts again for KCOD and KWRL. Traded out the PROB30 group for
a TEMPO group for the afternoon, with higher confidence of
brief impacts at KCOD.

&&

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

&&

$$

UPDATE...Gerhardt
DISCUSSION...Lowe
AVIATION...Straub