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Area forecast discussion 
National Weather Service Riverton Wyoming
211 am MST sun Mar 1 2015

Short through Tuesday night

An interesting forecast period across western and central Wyoming. A
fairly quiet beginning as linger activity other southern Wyoming
tapers off this morning. Morning inversions will develop...with
patchy fog possible across much of the low lying areas.

A brief period of dry conditions anticipated through the overnight
hours. While the dry period is area of low pressure
will move south along the Pacific coastline...finally heading inland
towards The Four Corners region late tonight and into Monday. As
this system progresses it will send snowfall across the southern
third of the forecast area...especially impacting southern
Sweetwater County by Monday morning. Snowfall will increase Monday
afternoon and Monday night...and is favorable to become heavy at
times. Snowfall accumulations of 4 to 7 inches are possible by
Tuesday evening...and are supported by National centers. Some
higher amounts are possible south of Interstate 80. With concerns
relating to this system mounting...have issued a Winter Storm Watch
for the County. Interstate 80 will be impacted...though again...the
greatest area of impact looks to be south of the
Interstate...especially along the Wyoming and Colorado border.

As this system is impacting the southern portion of the forecast
area... a wave of low pressure looks to send a Canadian system into
northern Wyoming by late Monday night. Snowfall with this system
will especially impact the northern mountains...and will continue to
be monitored. Eventually...the northern system looks to take over
the southern system...with snowfall spreading to include the vast
majority of the forecast area during the very early morning hours of
Tuesday. All situations will continue to be monitored...though
regardless even to amounts...expect a return to cooler weather with
snowfall very favorable over the area.

Long term...Wednesday through Sunday

Northwest flow is expected to dominate the extended with at least
one distinct shortwave trough and associated weak cold front sliding
across the area in the Friday/Friday night time frame. Otherwise...a
relatively dry northwest flow is expected. Will introduce slight
mountain probability of precipitation for this system Friday/Friday night...but kept the
lower elevations dry for this system appears to have
limited available moisture. Cannot rule out isolated mountain snow
showers on other days mainly over the northwest/northern
mountains...but previous forecasts were dry...and moisture is not
exciting...thus have kept the ongoing dry forecast.

Temperatures on Wednesday will be 15 to 25 degrees below
average...with some areas seeing highs about 30 degrees below
average. A warming trend will occur late this week with most areas
returning to seasonal levels by Friday. The exception will probably
be typical trapped central basins where models tend to warm them up
too quickly. A weak cold front Friday/Friday night...might actually
help mix out those trapped basins.


Aviation.../12z issuance/

East of The Divide...kcod/kcpr/klnd/kriw/kwrl routes

VFR to MVFR conditions will occur through 18z with areas of low
clouds and flurries to light snow. Expect some mountain obscuration
until 18z as well. VFR conditions will prevail by 21z and then
through 12z Monday.

West of The Divide...kbpi/kjac/kpna/krks routes

Over the south until 15z VFR to MVFR conditions will occur due to
lower clouds and areas of light snow. Low clouds will linger in some
areas until 19z. After 22z VFR conditions will prevail over the
region through 12z Monday.

Kpna...kbpi and kjac airports will see VFR conditions prevail through
the forecast period.


Fire weather...

Another return to winter expected over the next few days. Generally
dry conditions anticipated today...with morning inversions and
related patchy fog possible. A wintry system will then move into
southern Wyoming Monday morning...spreading snowfall across
Sweetwater County. Another system will then move into northern
Wyoming Monday night spreading snowfall across the northern third of
the forecast area. These two system are expected to join during the
very early morning of Tuesday...with widespread snowfall
anticipated. It appears as though the greatest snowfall amounts may
fall over southern Wyoming...with a Winter Storm Watch issued for
the area. Stay tuned for updates to this upcoming storm system.


Riw watches/warnings/advisories...
Winter Storm Watch from late tonight through Tuesday afternoon



Short term...branham
long term...wm
fire weather...branham

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