000
FXUS65 KRIW 140936
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
336 AM MDT Sun Apr 14 2024

.KEY MESSAGES...

- Near record high warmth continues across the Cowboy State this weekend,
  especially areas east of the Divide.

- The gusty winds arrive today with parts of Fremont, Natrona,
  and Sweetwater Counties possibly seeing gusts near 40 mph at
  times.

- The upcoming week looks to be quite unsettled with showers and thunderstorms
  developing Monday afternoon.

- Unsettled weather will continues by the early morning
  Wednesday, with chances for accumulating snow in the northern
  mountains and below normal temperatures across the state.

&&

.DISCUSSION...
Issued at 320 AM MDT Sun Apr 14 2024

Today will be the last day of well above normal warmth, as all good
things must eventually come to an end. Ridging that has been over
the central CONUS for the past few days begins to break down, as an
approaching Pacific system nears. Temperatures are still expected to
be 15 to 20 degrees above normal, especially east of the Divide.
Highs west of the Divide range from the mid 50s to upper 60s and in
the low to upper 70s east of the Divide. Winds increase today as a
closed Pacific upper-level low moves over the Great Basin. As the
low nears, the pressure gradient will tighten and southwesterly flow
will increase. Southwesterly flow favored areas in parts of Natrona,
Fremont, and Sweetwater Counties likely (50-80%) see the strongest
winds, with gusts of 35+ mph at times. Other parts of the state have
a good chance (30-60%) of seeing some breezy conditions today, with
periodic gusts of 25+ mph. Most of the state remains dry as well,
with the only exception being parts of western WY, which may see an
isolated shower during the evening, as a weak cold front nears.

The main concern today will be elevated to critical fire weather
conditions. A Red Flag Warning remains in effect for parts of
Natrona County due to the unseasonably warm temperatures, gusty
winds, low RH, and critical fuels. Elsewhere, elevated to near-
critical fire weather conditions will continue across parts of
Fremont, Sweetwater, Johnson and Sublette Counties. Will reissue a
Rangeland Fire Danger (RFD) statement as a result. Burning is highly
discouraged today due to these conditions.

The upcoming week is looking unsettled, with two disturbances that
look to be the key contributors. The first disturbance is a Pacific
low that will gradually move to the south of the state Monday. An
associated cold front will move through the state early Monday,
making its way through the state by the evening. As mentioned
earlier, a few showers will be possible over western WY late Sunday
into the early morning on Monday. The majority of the state looks to
remain dry for the morning but precipitation begins to develop by
the early afternoon. Showers look to become widespread through the
afternoon and evening, with most of the state having a (50-80%)
chance of seeing at least a brief shower. Thunderstorms are a
possibility Monday afternoon and evening, with most of the state
having a chance (10-25%) for a few rumbles of thunder and possibly a
isolated strong gust of wind. One area to note is Johnson County,
where CAMs are showing a boundary setup and sit over the
northeastern corner of the county. This boundary will keep warmer
and more moist air to the east of it so if this were to shift
farther west, then this unstable air would shift with it. As of
right now this corner of the county has a chance to see (15-25%) an
isolated strong thunderstorm during the afternoon/evening on Monday.
The main hazards with any strong thunderstorms that are able to
develop in this area would be small hail along with strong outflow
gusts. The late evening Monday into the early morning Tuesday will
see light to moderate rainfall across eastern parts of Johnson and
Natrona Counties specifically areas east of the I-25 corridor, as
the low shifts east and 700mb flow becomes northerly. Tuesday will
see lee cyclogenesis occur as a potent low develops over the central
High Plains. The pressure gradient will tighten quickly during the
very early morning hours Tuesday, with 700 mb winds nearing 50+
knots in parts of the eastern CWA. Surface winds will increase
during this time period with parts of the eastern CWA having a (20-
50%) chance of seeing periodic gusts of 45+ mph. Winds decrease and
showers dissipate by the late morning, as the low moves farther east
and the pressure gradient relaxes.

The second disturbance arrives early Wednesday morning across parts
of northern WY. Models have come into a better agreement regarding
the track of this disturbance. The setup is a trough moving south
from Canada and digging across the northern Rockies. Impacts
currently look to be limited to the higher elevations of northern
WY, where colder temperatures will be present and should support
accumulating snow. 700 mb temperatures range from -10 to -15 Celsius
by Wednesday night which will create some chilly lows for Thursday
morning. Precipitation looks to be mainly limited to the northern
half of the CWA with the highest QPF currently across the Absarokas
and Bighorns. There still is a lot of uncertainty with this
disturbance, as temperatures will be a key part in determining if
any snow can accumulate across low elevation basins. Overall, enjoy
the warm, pleasant, and quiet weather today, as the upcoming week
looks to become active with below normal temperatures by
midweek.

&&

.AVIATION /06Z TAFS THROUGH 06Z MONDAY/...
Issued at 922 PM MDT Sat Apr 13 2024

VFR conditions for the entirety of the period for all TAF
sites. Light winds and mainly clear skies overnight under a weak
inversion through Sunday morning. After 16-19Z, winds will
increase once again with daytime heating and mixing to the
surface under continued mainly clear skies. Winds will diminish
towards sunset after 00-01Z following the diurnal trends the
past couple of days. No other weather elements are expected at
this time.

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

&&

.FIRE WEATHER...
Issued at 320 AM MDT Sun Apr 14 2024

Unseasonably warm temperatures remain across the state today,
especially east of the Divide. Highs will be in the upper 50s to
upper 60s west of the Divide and in the low to upper 70s east of
the Divide. Southwesterly winds increase today, with the
strongest gusts nearing 40 mph in portions of Fremont, Natrona,
and Sweetwater Counties. RH values continue to be dry with
percentages of 10-15% across most of Natrona, Fremont,
Sweetwater, and Sublette Counties. RH is expected to be slightly
higher in Johnson County with values as low as 15-20%. A Red
Flag Warning remains in place for Zone 280 due to critical fire
weather conditions in combination with critical fuels.
Rangeland Fire Danger statements have been issued again for
Fremont, Sweetwater, Sublette, and Johnson Counties due to
elevated to near-critical fire weather conditions.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning until 7 PM MDT this evening for WYZ280.

&&

$$

DISCUSSION...Dziewaltowski
AVIATION...Lowe
FIRE WEATHER...Straub