789
FXUS65 KRIW 011952
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
152 PM MDT Mon Jul 1 2024

.KEY MESSAGES...

- Marginal (Level 1 of 5) Risk of severe thunderstorms across
  north-central Wyoming through this evening. Large hail, strong
  winds, and frequent lightning are the primary concerns in the
  strongest storms.

- Continued cooler temperatures and increased precipitation
  chances through mid-week across northern Wyoming.

- Warm, dry, and breezy conditions expected across south-central
  and southwest Wyoming through the next week. Elevated to
  critical fire weather conditions in areas with cured fuels.

&&

.DISCUSSION...
Issued at 150 PM MDT Mon Jul 1 2024

As the cold front is draped across Wyoming, rain showers and
thunderstorms have been observed, as well as wind gusts along and
behind the front of 30 to 40 mph, even higher in wind prone areas
and from thunderstorm outflow. While the main shower and
thunderstorm activity will be up in north-central Wyoming, a few
showers and weak thunderstorms cannot be ruled out near the I-80
corridor east of Rock Springs. Up in north-central Wyoming there is
a Marginal Risk for severe thunderstorms where HiRes guidance is
showing 500-1000 J/kg of SBCAPE and 35-45 knots of bulk shear, which
is substantial to sustain convection. Based on the latest HiRes
model runs, the most likely time frame for the strongest storms in
north-central Wyoming is from 2 PM to 6 PM. Showers will linger
overnight and through Tuesday morning as another shortwave pushes
through northern Wyoming. While there is still the potential for
thunderstorms Tuesday, the severe parameters are much more limited,
especially the instability, so any thunderstorms that do develop
will likely not be severe. The main shower and thunderstorm activity
will decrease through Tuesday evening.

Headed into the Independence Day holiday, the Riverton forecast area
is positioned along the east side of an upper-level ridge as
multiple shortwaves are embedded in the flow. This will help
moderate temperatures and keep them, on average, near-normal. In
addition, there are chances for showers and thunderstorm each
afternoon through Thursday, particularly across the northern
half of Wyoming. Across the High Desert Region, warm
temperatures, low afternoon relative humidity values, and gusty
winds will create critical fire weather conditions where the
fuels are cured and ready to burn. Due to the timing of these
conditions being near the 4th of July, caution is recommended if
opting to participate in the festivities. Following the
shortwave passage on the 4th of July, the upper-level ridge
shifts eastward, increasing temperatures and decreasing
precipitation chances headed into the weekend.

&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 1145 AM MDT Mon Jul 1 2024

A weather system, with an associated cold front is passing through
the area today. As a result scattered rain showers and thunderstorms
will develop/have developed and will continue to develop across the
northern half of the area this afternoon through tonight. Terminals
most likely to be impacted by these showers and storms are KJAC,
KCOD, and KWRL where TEMPO groups are included in the TAFs. The cold
front is passing through the area this afternoon/evening and wind
will shift northerly once it passes. An area of rain is likely (60-
70%) to pass over KCOD early Tuesday morning. Conditions will remain
VFR through the TAF period, excluding terminals where a thunderstorm
moves directly overhead, which will result in reductions in VIS to
MVFR (possibly IFR 20-30% chance).

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

&&

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

&&

$$

DISCUSSION...Gross
AVIATION...Rowe