749
FXUS65 KRIW 190455
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
1055 PM MDT Wed Sep 18 2024

.KEY MESSAGES...

- Windy this afternoon, with lighter winds returning for Thursday.

- Light rain and mountain snow continues this afternoon,
  decreasing this evening and overnight.

- Thursday is dry, with slightly warmer temperatures.

- The next weather system comes this weekend. Most of its
  impacts remain outside the area, but cooler temperatures and
  isolated rain is possible.

&&

.DISCUSSION...
Issued at 1226 PM MDT Wed Sep 18 2024

Current satellite shows an occluding low pressure system, centered
over eastern Montana. Its influence today keeps cool temperatures
and gusty winds. The main impacts from it decrease starting mid-
afternoon through the overnight hours.

A tight pressure gradient keeps strong west to southwest winds this
afternoon. Gusts ranging from 20 to 70 mph continue across the area.
Recent model trends show that these winds should begin to decrease
after 3pm MDT this afternoon. Winds should be less than 20 mph by
midnight, with the exception of the higher elevations, which
continue to gust through Thursday morning. Wrap around moisture
keeps precipitation falling across northwest and northern Wyoming as
well. This should remain light. Snow levels are mostly above 10000
feet, but some areas are as low as 9000 feet. Precipitation
decreases through the afternoon, with some lingering showers lasting
until Thursday morning. All precipitation should be done by sunrise
Thursday. High temperatures remain on the cool side today, with 50s
to 60s west of the Divide, and 60s to low 70s east.

As the low exits the area, Thursday is much calmer with the winds.
Most areas are 10 mph or less. The Wind Corridor gets afternoon
gusts to around 20 mph. Otherwise, no precipitation is expected,
with high temperatures peaking a little warmer than today. Friday,
temperatures are a little higher. Some moisture could bring very
isolated (20%) showers to northwest and north Wyoming.

An upper-level low tracks into the Four Corner area Saturday. Most
of its influence should remain south and southeast of the area
through the weekend. That being said, temperatures decrease, with
highs returning to below seasonal values. No widespread
precipitation is expected given the current model tracks, but some
isolated (15% to 30%) showers could occur. These would be favored
for southeastern locations of the area.

Past this weekend, ensemble models are bringing in a ridge by the
middle of next week. This would favor warmer and drier conditions to
end the month.

&&

.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 1055 PM MDT Wed Sep 18 2024

VFR conditions are expected to prevail at terminals through the
period as the previous system departs. KJAC should begin to see
ceilings rise 06-08Z. Clouds will decrease at all terminals through
Thursday morning. Otherwise, wind will be relatively light through
the period outside of gusts to 20 knots at KCPR Thursday afternoon.
No precipitation is expected in the area.

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

&&

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

&&

$$

DISCUSSION...Wittmann
AVIATION...Myers