Area Forecast Discussion
Issued by NWS Riverton, WY

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FXUS65 KRIW 140500
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
1000 PM MST Tue Nov 13 2018

.SHORT TERM...This evening through Wednesday night

Upper level ridging is still in control through tonight and
Wednesday so dry weather across the FA. However, it has begun to
flatten out as the next trough approaches the Northwest US. The
tightening gradient has produced gusty winds from Rock Springs up
through Casper today and will remain gusty, though slightly slower,
through the night before picking back up tomorrow morning. Models
still want to run higher with temps in the basins on Wednesday so I
walked them back just a bit. ForecastBuilder came in with very low
winds for the Tetons tomorrow evening though HiRes models were
indicating gusts into the 20s. Increased winds in the area to bring
winds closer to surrounding area.

.LONG TERM...Thursday through Tuesday

A mid to upper level ridge axis is progged by the models to be
across the region on Thursday in advance of the next storm system.
A southwest wind flow will be across the region with temps
expected to be about 10 degrees above normal across central/
western Wyoming. The long term models are in somewhat fair
agreement involving the timing/impacts involving the short wave
trough moving through the forecast area between Friday afternoon
to Saturday morning. An associated surface cold front is progged
by the GFS/ECMWF models to move across the region by Friday
evening. It is still expected that morning high temps will be
common across the Big Horn Basin and Johnson and Natrona
counties, with falling afternoon temps expected. The main initial
question will be if the precipitaion along and ahead of the cold
front begins as rain.

In the cold advection in the wake of the cold front, snow/snow
showers are expected to spread north to south across the forecast
area by late Friday and continuing into Saturday morning,
primarily impacting areas along and east of the Divide. Have kept
snow pops in the likely category due to right entrance jet region
moving across the area by late Friday and decent forcing across
the area. Will continue with the current trending for now of the
snow ending from north to south from late Friday night into early
Saturday morning. The potential will definitely be there for
accumulating snow and will need to continue to monitor the next
couple of model runs to determine better the amounts, which could
approach winter weather advisory criteria in some locations
between late Friday and into Saturday morning.

The GFS/ECMWF models are in decent agreement of bringing in an
upper ridge across the Pacific Northwest Sunday and Monday and an
upper low moving into central/southern California by Monday
night. The temps will be tricky behind the Friday/Saturday snow
event, with the potential for a decently strong inversions east of
the Divide where there could be more snow cover especially for
Sunday and Monday. Will continue with basically a dry forecast
through the end of the extended forecast period with the upper low
progged to open up and move into the southern Rockies.


&&

.AVIATION...For the 06Z TAFS through 06Z Wednesday evening

VFR conditions will prevail at all terminals through 06Z/Thursday.
KCPR will see a southwest 10-15kt wind increase to 20G30kts around
15Z-16Z/Wednesday before decreasing again just prior to sunset. KRKS
will also see west-southwest wind around 15kts. Other terminals will
generally experience wind less than 12kts.

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

&&

.FIRE WEATHER...

Expect dry weather for all areas this afternoon through tomorrow. A
gusty wind will continue from the Red Desert through Casper and form
again Wednesday morning. Basin inversions will strengthen quickly
tonight and will hold through the day again tomorrow. Relative
humidity will remain above critical levels. Mixing and smoke
dispersal will be generally poor except fair in the breezier
locations.

&&

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

$$

SHORT TERM...Hulme
LONG TERM...Troutman
AVIATION...CNJ
FIRE WEATHER...Hulme


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