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497
FXUS65 KRIW 241744 AAA
AFDRIW

Area Forecast Discussion...Update
National Weather Service Riverton WY
1145 AM MDT Sat Jun 24 2017

.SHORT TERM...Saturday through Monday night

Like yesterday, most areas should stay mainly dry today. However, a
weak shortwave tracking across the area and a bit more moisture will
bring isolated thunderstorms across portions of the northern
mountains this afternoon and evening. However, coverage will once
again be very sparse. As for temperatures, they will remain below
normal but will be a few degrees warmer than yesterday. Wind
should remain largely light to moderate.

Sunday looks to be a dry day as ridging builds across the state.
With building heights and thicknesses, temperatures will also begin
an upward trend, but still remain below normal. All in all it looks
like a nice end to the weekend with sunshine and some mid to high
level clouds along with mainly light to moderate winds.

The heat will return on Monday as flow turns to the southwest. Many
of the lower elevations will likely see high temperatures return the
90s as well. In addition, the chance of thunderstorms will return as
well as the first in a series of shortwaves will approach the area.
At this point, the wave looks to be a late arrival so a vast
majority of the area should have a dry day. And with many of the
recent systems, the best chance of any storms would be across the
north where best dynamics will be.

.LONG TERM...Tuesday through Saturday

Overview...A cold front will push east across the area Tuesday
bringing chances of showers and thunderstorms across the north and
central; windy and warm conditions across southern Wyoming will
elevate the fire danger.  Cooler and unsettled conditions will
follow the cold front Wednesday through Friday with chances of
showers and thunderstorms, mainly across the north and east each
day.

Discussion...Upper low over the Gulf of Alaska early this morning is
expected to drift east along roughly 55N into Alberta/Saskatchewan
on Tuesday, while the first in a series of Pacific shortwaves moves
east across Wyoming/Montana.  Surface cold front is expected to be
push east through the area Tuesday morning, with the best moisture
and instability (severe potential) over the High Plains by Tuesday
afternoon.  We may still see a few strong storms with hail across
northern Wyoming, while the main threat further south looks to be
strong wind gusts with drier air in the low levels.  A succession of
shortwaves in broad cyclonic flow is expected to persist over the
northern Rockies and northern Plains through Friday, bringing
chances of showers and thunderstorms with Thursday and Friday
looking to be the coolest days of the upcoming week, lower elevation
highs mostly in the 70s.  The upper flow, ridge over the eastern
Pacific and trough over the northern Plains is expected to deamplify
Friday and Saturday, which will likely lead to a warmer and drier
pattern emerging next weekend.

&&

.AVIATION...18Z Issuance

VFR conditions to prevail at all terminals through 12Z/Sun (Sunday
morning). SKC to localized SCT CIGs 070-090 ft mainly east of the
divide. No precipitation expected through the period. Winds
relatively light and variable to north to northwest with only an
occasional afternoon gust to 15 kts or so after the atmosphere has
fully mixed out in the afternoon. LLWS to 30 kts possible across
southern Wyoming after 04Z Sunday (Saturday evening). VFR conditions
expected Sunday with sct shallow cumulus development with cloud bases
around 9k west of the divide, 110k east, and 7k north. Clear skies south.

&&

.FIRE WEATHER...

Mainly dry conditions should continue through the weekend. Although
an isolated shower or thunderstorm may occur across portions of the
northern mountains, most areas will see nothing. Temperatures will
be somewhat warmer than yesterday, but remain below seasonal
averages. Although some areas in Sweetwater County will have
relative humidity fall below 15 percent at times, wind should remain
light to moderate. Mixing and smoke dispersal will range from fair
in the basins to good to very good in the normally breezier
locations.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...Hattings
LONG TERM...Meunier
AVIATION...Braun/lipson
FIRE WEATHER...Hattings