Area Forecast Discussion
Issued by NWS Riverton, WY

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000
FXUS65 KRIW 200500
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
1000 PM MST Mon Feb 19 2018

.UPDATE...
Issued at 802 PM MST Mon Feb 19 2018

...Snow tapering off or ending across southern and central Wyoming
tonight...

The winter storm system that brought significant snow to the area
is moving out of region tonight. Areas of light patchy snow or
flurries will continue overnight with only light accumulations.
However, bitter cold temperatures will take the place of the snow
with morning lows ranging from 5 to 25 degrees below zero.

&&

.SHORT TERM...(This evening through Thursday) Issued at 802 PM
MST Mon Feb 19 2018

Impressive snowstorm continues across our sern zones, particularly
around Casper where upper support has been producing impressive
heavy snow periods all day long with large snow clusters occurring.
GOES16 minute data imagery has been impressive showing the
convective elements stretching from sern Sweetwater County up to
Casper and Casper Mountain. Snowfall amounts over a foot are
widespread in Casper with amounts still piling up. Only recently
has the cloud enhancement started to decrease leading to lighter
snows as of 2 pm. Lighter snows continue further west into
central and southwest Wyoming but still accumulating with local
moderate bursts. Cyclonic nose of the jet will finally move just
southeast of our area this evening allowing a more general lighter
snow to return to srn Natrona county. Clouds may linger overnight
in many areas east of the divide which makes for a challenging
temperature forecast. Any spots that clear could be colder than
forecast but we`re still forecasting widespread -10 to
- 20 across the entire lower elevations with even colder temps
forecast for YNP and the low lying areas of the Bighorn Basin.
Bitterly cold through the short term with highs only in the single
digits east of the divide and around 10 west. The mountains will
be near or below zero for highs yet Tuesday. Wednesday morning
will likely be the coldest morning as less clouds and good snow
cover allow temps to plummet even more than tonight. Minus 15 to
-25 in many locations. Not much warmer Wednesday but with some
 breezes the wind corridor and foothills will be a little warmer.
 Mainly 10 above into the teens lower elevations with zero to
 single digits mountains. Slow moderation continues into Tuesday
 but still quite cold. A few flurries will occur in the high
 country through the short term with possible light snow
 developing Thursday with the next trough approaching.

.LONG TERM...(Thursday night through Monday) Issued at 802 PM MST
Mon Feb 19 2018

Once again with the active weather today only minor tweaks to the
long term. It still looks rather cold through the period with a long
wave trough remaining over the Rockies and keeping below normal
temperatures in through the period with only a couple of brief
breaks. At this point, mainly dry conditions look to dominate
through Saturday with only a few showers across the western
mountains and possibly some light snow across southern Wyoming as a
system moves to the south of Wyoming across Colorado. A more
substantial system may approach Saturday night into Sunday and bring
another round of snow into the west. There is still some question as
to how much can translate East of the Divide however.

&&

.AVIATION...(For the 06Z TAFS through 06Z Wednesday)
Issued at 1000 PM MST Mon Feb 19 2018

West of the Continental Divide...KJAC, KBPI, KPNA and KRKS

Some lingering light snow through 12Z with local MVFR conditions.
Otherwise VFR conditions will prevail after 12Z through 06Z Wed.
Snow showers will occur in the western mountains through 03Z Wed
with some mountain top obscuration. Will have VCSH in the western
terminal sites in the afternoon into early evening.

East of the Continental Divide...KCPR, KCOD, KRIW, KLND, and KWRL

Lingering light snow in places through 14Z with local MVFR
conditions. After 14Z VFR conditions will prevail over the area.

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 802 PM MST Mon Feb 19 2018

Snow will persist across the south and east part of the area through
this evening before tapering off to flurries. It will be bitterly
cold through at least mid week. Smoke dispersion will be poor to
fair (east of the Divide) to good (west of the divide) Tuesday and
in the basins and valleys through mid week. Some breezes across the
foothills and wind corridor (Jeffrey City to Casper) will see some
better mixing with breezy southwest winds by Wednesday.

&&

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

&&

$$

UPDATE...Braun
SHORT TERM...Skrbac
LONG TERM...Hattings
AVIATION...AR
FIRE WEATHER...Skrbac



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