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Area forecast discussion 
National Weather Service Riverton Wyoming
356 am MDT Friday Sep 19 2014

Short through Sunday night

Showers and thunderstorms continue to move through the forecast area
this morning. Frequent lightning has been associated with some storm
activity...and this threat will linger this morning. The threat will
diminish a bit during the late morning hours...especially across the
north. An area of low pressure off the coast of Southern California
will help to push moisture across the southern half of the forecast
area through the afternoon. Showers and thunderstorms will be
present...with the threats for gusty wind and small hail.

Activity will weaken this afternoon as northwest flow builds over
the area. Generally dry conditions expected by Saturday morning
across the area. Dry conditions associated with this system will
last through Sunday morning. Temperatures will continue to follow a
cooling trend over the next several days.

The previously mentioned area of low pressure will move across the
Desert Southwest Sunday morning...helping to generate some shower
and thunderstorm activity Sunday morning. Shower coverage will
continue to increase through the afternoon...with scattered showers
anticipated by Sunday evening. Models in fair agreement with this
progression with just subtle differences on intensity and areas of

Long term...Monday through Friday

GFS and European model (ecmwf) continue to bring an upper low across the forecast
area Sunday evening...through the day Monday...with lingering
effects still being felt on Tuesday. 700 mb temperatures appear to
be to warm for snow with this mainly showers and
thunderstorms are expected. Model quantitative precipitation forecast is showing some good rainfall
possible Sunday evening through Monday...mainly across western and
northern portions. This upper low will exit into the northern plains
during the day Tuesday...ending chances for shower and thunderstorms
from west to east. Warming temperatures are then expected for
Wednesday and a brief ridge of high pressure moves
in...bringing with it warm and dry air. Above normal temperatures
could then be expected...with readings in the 80s possible for
Wednesday and especially Thursday...mainly east of The Divide. An
interesting weather pattern will then set up late in the forecast
period. A large trough pushes onshore Thursday evening through
Friday morning. GFS is a bit more progressive with this system...and
showing an initial push of moisture could bring some thunderstorms
as early as Thursday afternoon and evening across western Wyoming.
GFS solution shows showers...thunderstorms...and possibly some
higher elevation snow...will then be possible for Friday...with the
best chances coming across the west. European model (ecmwf) is a bit slow with this
large system...and delays precipitation to Saturday and Sunday.
Either way...a stronger storm system looks to bring widespread
precipitation for late next week into the weekend.


Aviation.../12z issuance/

Scattered showers and storms will end from west to east early this
morning. Local MVFR conditions will be possible with some mountain
obscuration. The area from krks to kcpr will see linger showers and
isolated storms from 12z until 17z. Wind gusts to 30 knots will be
likely with storms. Otherwise VFR conditions will prevail from 12z
through 12z Saturday. Isolated showers or storms may occur along the
southern Wyoming border from 18z through 02z but will stay south of the
krks Airport.


Fire weather...

Showers and thunderstorms across the area will continue this
morning. Though frequent lightning and some gusty wind will remain
possible this morning...coverage is expected to weaken through the
morning and afternoon hours. Dry conditions will move in during the
overnight hours...and linger through Sunday morning. Temperatures
will cool over the next several days under the current weather
pattern...with increased humidity over the area. Fire weather
concerns should be on the low side the next few days.


Riw watches/warnings/advisories...


Short term...branham
long term...Anglin
fire weather...branham

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