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Area forecast discussion 
National Weather Service Riverton Wyoming
125 PM MST Thursday Mar 5 2015

Short term...tonight through Friday

High clouds continue across the area today and will continue
streaming in from the north tonight into Friday. These clouds should
limit temperatures from moderating too much in the valleys and
basins...as well as limit any fog formation. Breezy winds continue
across southern portions into Natrona County...as well as along the
Cody foothills. This will help mix the Arctic air from these areas.
Gusty winds will continue tonight into tomorrow for these
locations...except portions of the Green River basin. Strong
inversions are expected in locations that still have significant
snow cover and light winds...which will keep the temperatures down
as well. Strong low level wind shear will also pose an issue...with
30-40kt winds just above the inversion.

Long term...Friday night through Thursday night

Drying and warming will be the main story through much of the
forecast period from Friday night to Wednesday. The high pressure
ridge over the west will shift east and flatten with time with
zonal west southwest flow replacing the highly amplified northwest
flow Monday and Tuesday. This part of the forecast looks pretty
straight forward with fair model agreement, this is not the story
Wednesday night through Thursday night as eventually Pacific moisture
and ejecting troughs form the main low in the eastern Pacific migrates
east and spreads clouds and snow with cooler temperatures into the
western and eventually northern mountains. European model (ecmwf) about a full day
slower than the GFS. Forecast is somewhat a compromise between the two
with lower chances of precipitation than the GFS but higher than
the European model (ecmwf). Temperatures ramp up into the upper 40s and 50s which
should bring on significant snow melt.

&&

Aviation.../00z issuance/

VFR conditions with mainly scattered-broken fl200 will prevail through the
period. Areas of low level wind shear remain possible along the east slopes of the
Absaroka Range...vicinity kdub-kcod...through the period with winds
at fl080 30-35kt. This will lower to fl065-070 after 04z Friday.
Low level wind shear of 30-35kt at fl070 will also be possible near kriw.

&&

Fire weather...

A cold air mass will remain over much of the area tonight...before
beginning to moderate Friday and into the weekend. Low mixing
heights and poor smoke dispersal will continue in the valleys and
basins this afternoon and tonight. Gusty winds will bring better
ventilation and higher mixing heights across normally
windier areas like east of the absarokas and from Rock Springs to
Casper.

&&

Riw watches/warnings/advisories...
none.
&&

$$

Short term...lavoie
long term...c.Baker
aviation...lavoie
fire weather...lavoie

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