261
FXUS65 KRIW 182332
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
532 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 /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 530 PM MDT Wed Sep 18 2024

Gusty westerly surface wind 15-30kts slows between 00Z-03Z/Thursday
in wrap-around counter-clockwise flow around an upper-level low over
Montana. All terminals to be VFR through Thursday. Persistent VFR
cloud decks and scattered light showers across the far west and
north gradually diminish and ceilings rise late tonight as mid-level
moisture lifts to the north with the upper low. Enough clearing of
mid-level clouds could lead to patchy fog around KJAC after
08Z/Thursday until 15Z/Thursday. This potential will need to be
monitored. Any lingering light showers decrease between 06Z-
12Z/Thursday. Surface wind speeds less at or less than 10kts are
expected after 12Z/Thursday with the exception of 10-18kt southwest
wind at KCPR.

Mountain tops frequently obscured above 10K feet MSL until
06Z/Thursday across the northwest quadrant of Wyoming.

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...CNJ