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000
FXUS65 KRIW 131705
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
1105 AM MDT Sat Apr 13 2024

.KEY MESSAGES...

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

- Breezy conditions continue across the state through the weekend.

- A Red Flag Warning has been issued for parts of Natrona
  County through the weekend. Burning is highly discouraged
  over the weekend across much of the state.

- Uncertainty remains high in regard to next weeks forecast with
  the possibility for a more active and cooler pattern.

&&

.DISCUSSION...
Issued at 258 AM MDT Sat Apr 13 2024

An area of dirty ridging has set itself up over the western CONUS.
This will keep warm and dry conditions in place over the Cowboy
State through the weekend. Friday saw record highs either be tied or
broken in parts of the state. Riverton reached a high of 73 degrees,
which broke the previous record of 72 degrees set back in 2003.
Record highs were tied at Casper with 75 degrees (1992) and Rock
Springs with 71 degrees (1988). This well above normal, record high
warmth continues through the weekend, with multiple sites having the
possibility of seeing records met or broken.

Overall, the weather will remain analogous for the next few days.
Temperatures, remain warm with highs nearly 15 to 20 degrees above
normal, especially east of the Divide. Highs for today are forecast
to be in the mid 50s to mid 60s west of the Divide and in the low to
mid 70s east of the Divide. Winds look to become breezy today with
10 to 20 mph gusts. Natrona and Sweetwater Counties have a better
chance (40-60%) of seeing stronger gusts near 25 mph today. Lastly
dry RH values look to stagnate across parts of Sweetwater, Natrona,
and Fremont Counties. RH values are currently forecast to remain
rather dry through the weekend, ranging from 10-20%. The reason this
may be of concern, is with the combination of warm temperatures and
breezy winds, elevated to critical fire weather conditions will be
possible over these areas for today. A Red Flag Warning has been
issued for parts of Natrona County due to the warm temperatures,
breezy winds, low RH, and critical fuels. Elsewhere, parts of
Fremont, Sweetwater, Johnson and Sublette Counties have a RFD
issued, due to the elevated fire weather conditions that are likely
to occur. Burning is highly discouraged this weekend due to the
conditions, whether there is a RFD or Red Flag Warning for your area.

The well above normal temperatures continue through the remainder of
the weekend, with cooler but still above normal temperatures
expected by Monday. The strongest winds arrive Sunday, as the
gradient tightens and southwesterly flow increases due to a nearing
Pacific disturbance moving south of the CWA. Southwesterly flow
favored areas in parts of Natrona, Fremont, and Sweetwater Counties
likely (40-70%) 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 Sunday, with gusts of 20 to 30 mph.
Sunday looks to be the worst day for fire weather conditions, with
gusts near 35 mph for these areas, critical fire weather conditions
are likely to develop. The Red Flag Warning will remain in effect
for Natrona County on Sunday, with other areas possibly seeing
additional highlights but these will be assessed by the day shift.

Next week is still up in the air, with a lot of uncertainty
regarding the forecast. Models still indicate two main disturbances
that move through the region over the course of the week. The first
is a Pacific disturbance that looks to stay mainly to the south.
Impacts from this system look to remain minimal, with scattered
showers possible Monday afternoon through Tuesday morning. By
Tuesday morning this system will quickly slingshot towards the Great
Plains, as a potent Canadian disturbance barrels south from western
Canada. However, what happens between these two systems is still
highly uncertain. There are two scenarios that models are showing;
one with widespread impacts to the CWA and the other having little
to no impacts. The first scenario has the Canadian system move south
into the Rockies with little to no interaction with the Pacific
system. This would bring widespread precipitation and below normal
temperatures to the region, along with chance for mountain snow and
valley mixing. One thing to note with this possible outcome is the
GFS continues to show the greatest impacts for this scenario. Recent
runs of the GFS weaken this disturbance, with it likely remaining an
open wave and never truly organizing into a closed low. The other
scenario has the Canadian system remain to the north, and the
Pacific disturbance bomb out over the Plains. This creates a potent
upper-level low far to the east with only minimal impacts. Winds
could possibly be a concern with this scenario as the low creates a
tight gradient over the region. Overall, there are still a lot of
unknowns regarding the forecast for next week, with the forecast
trending towards below normal temperatures and more active weather
but not as drastic as originally thought.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1102 AM MDT Sat Apr 13 2024

High pressure remains anchored over Wyoming, so mostly clear skies
and dry conditions will continue through the TAF period. Isolated
virga showers will occur in the Bighorn Basin this afternoon, with
little impact to flight operations. A breezy southwest wind will
develop this afternoon across the area. Overall, sustained wind will
be 10-15 knots and gusts will be 15-25 knots, this afternoon
before decreasing this evening. Stronger wind is expected
tomorrow, with some terminals having wind increase late Sunday
morning. Wind will increase at all terminals Sunday afternoon.

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 1010 AM MDT Sat Apr 13 2024

Unusually warm and dry conditions will continue today and Sunday
across most of the lower elevations of western and central WY,
with most areas noting humidity levels falling below 15 percent
both days. Wind gusts will reach 25 to 30 mph across Natrona
County today, and will gust 30 to 40 mph from Rock Springs to
Casper to Buffalo on Sunday. Warm temperatures overnight will
bring only fair humidity recovery only reaching 45 to 60
percent. Have issued a Red Flag Warning for Zone 280 (Lower
Natrona County) from noon today through 7PM Sunday where fuels
are more critical, and have issued RFD for Fremont, Johnson,
Sublette, and Sweetwater Counties for today, and will likely be
continued again Sunday.

&&

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

&&

$$

DISCUSSION...Dziewaltowski
AVIATION...Rowe
FIRE WEATHER...Straub