Area Forecast Discussion
Issued by NWS Riverton, WY

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FXUS65 KRIW 221655
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
1055 AM MDT Fri Mar 22 2024

.KEY MESSAGES...

- Isolated to scattered rain and mountain snow showers are expected
at times this evening through Saturday morning.

- Precipitation chances increase Saturday evening, with snow and
much colder temperatures becoming widespread Sunday.

- Cooler temperatures and precipitation chances continue through
  early next week.

&&

.DISCUSSION...
Issued at 408 AM MDT Fri Mar 22 2024

Light, jet-induced showers are currently observed over portions of
central and northern Wyoming. These will wane over the next few
hours as jet support moves away. Weak, transitory ridging will then
take over today. This will still allow for a few showers through the
day, mainly across the mountains of northern and western Wyoming.
Most of the area will remain dry through the afternoon, with highs
peaking around or above normal. A notable exception will be across
northern areas which will hold on to the colder temperatures behind
yesterday`s front.

The ridge will begin to flatten this evening as a leading shortwave
arrives ahead of a West Coast trough. Isolated showers will spread
from southwest to northeast after sunset, with light snow
accumulation in the mountains overnight. The western Wind River
Range will be most favored to pick up an inch or three given the
favorable southwesterly flow.

Rain and snow showers will increase in coverage beginning Saturday
afternoon as flow becomes cyclonically curved as the trough further
approaches. Otherwise, it will generally be another warm and windy
day for most as the surface pressure gradient increases. The trough
axis will finally sweep across the area Saturday night through
Sunday. A cold front will quickly push south Sunday morning as
surface pressure falls east of the Rockies. Rain across lower
elevations will transition to snow as this occurs through the
morning. Nearly all of the area will see at least a little snow, but
the best chances will be in the mountains and across lower
elevations east of the Continental Divide. Generally speaking, one
to three inches are expected east of the Divide. However, the
relatively warm ground and road temperatures - as well as
persistent spring solar radiation- will likely lead to fairly
efficient melting and thus limit more prolonged impacts across
lower elevation. The mountains will unsurprisingly see quite a
bit more snow, though likely staying in the advisory range if
current trends hold. In addition to the much colder temperatures
and snow on Sunday, post frontal wind will remain elevated
across the Bighorn Basin and Johnson/Natrona counties through
Sunday afternoon.

Snow will decrease Sunday evening as the main trough axis pulls
away. However, an active northwest flow pattern will set up to begin
the week. This will keep isolated shower chances going, especially
across western Wyoming. Temperatures look to remain below normal
through at least Tuesday before a slight warmup midweek. Ensemble
guidance then favors the next trough to approach Thursday, bringing
another round of widespread precipitation to the area.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 1037 AM MDT Fri Mar 22 2024

All TAF sites have lifted to VFR to start the period with
relatively light winds and scattered mid level clouds. RKS will
see gusts up to 25kts during the afternoon hours of peak heating
with lighter gusts up to 18kts possible at BPI. These will
diminish after 23Z towards sunset. Ahead of an approaching
shortwave, increasing mid and upper level clouds overnight with
chances for light rain/snow showers after 06-07Z west of the
Divide and to include all but RIW and CPR east of the Divide.
Confidence is low with its sporadic nature carrying VCSH with a
better chance west of the Divide after 12Z with a PROB30 group
for light snow and MVFR ceilings/visibility through the end of
the period. This will push into the next TAF cycle as well
through the afternoon with increasing winds east of the Divide
at that time.

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...Myers
AVIATION...Lowe


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