Area Forecast Discussion
Issued by NWS Riverton, WY

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FXUS65 KRIW 112343
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
540 PM MDT Fri Aug 11 2017

.SHORT TERM...(This evening through Monday)
Issued at 206 PM MDT Fri Aug 11 2017

A series of cool low pressure troughs moving across the Pacific
Northwest, the Northern Rockies and Southern Canada will converge
with warmer moist southwest flow on the west side of a flat high
pressure ridge over the Desert Southwest and Great Basin, over
Wyoming.  This will keep clouds and scattered showers with
isolated scattered thunderstorms over the area through Sunday.
Precipitation will be greatest over the mountains.  This will keep
temperatures depressed and relative humidity elevated.  With low
level north to east flow winds will be rather light outside of
thunderstorms which may produce strong erratic wind gusts.
Sunday night and Monday, west to southwest flow aloft will move
over the area with warming and drying.  Isolated showers and
thunderstorms will be possible but with much less coverage.
areas of west to southwest winds will spread from west to east
and become gusty.

.LONG TERM...(Monday night through Friday)
Issued at 206 PM MDT Fri Aug 11 2017

As a large low pressure trough moves inland along the Pacific
Northwest, southwest flow will move inland the high pressure ridge
over the Desert Southwest and Great Basin shifts east.  The Pacific
trough will also produce stronger south southwest flow over
the Northern Rockies and Southern Canada bringing an end to the
cool northwest flow.  Drying and warming will result as the flow
aloft over Wyoming shifts to the west and eventually to the
southwest.  Surface winds from the west and southwest will spread
from the west and southwest into central and eventually eastern
Wyoming through Friday.   This will significantly decrease
the afternoon and evening convection but not eliminate it
completely.

&&

.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 540 PM MDT Fri Aug 11 2017

The LND TAF has been NILed as of 00Z/Sat.  ASOS observations have
not been available for a week, and there is no estimated time of
return of service.  With the runway being under construction through
the end of October and no observations, the TAF will be NILed until
further notice.

A disturbance is move southeastward through eastern Montana, and
moisture and weak instability continue to stream eastward from the
northern Great Basin.  Scattered thunderstorms continue early this
evening.  Gusts over 30 kts along with some rain and small hail has
been observed.  VFR generally with local MVFR possible. The
convective activity will continue through 03Z-04Z/Sat, with some
isolated showers continuing overnight.  Similar conditions will
occur again on Saturday, though the thunderstorm coverage may not be
quite an extensive as Friday. Models are indicating the Absarokas,
Bighorns, and Wind River mountains for initial development, and the
NAM shows late afternoon and evening activity across Sublette and
Sweetwater counties.

&&

.FIRE WEATHER...
Issued AT 206 PM MDT Fri Aug 11 2017

A series of cool low pressure troughs moving across the Pacific
Northwest, the Northern Rockies and Southern Canada will converge
with warmer moist southwest flow on the west side of a flat high
pressure ridge over the Desert Southwest and Great Basin, over
Wyoming.  This will keep clouds and scattered showers with
isolated scattered thunderstorms over the area through Sunday.
Precipitation will be greatest over the mountains.  This will keep
temperatures depressed and relative humidity elevated.  With low
level north to east flow winds will be rather light outside of
thunderstorms which may produce strong erratic wind gusts.
Sunday night and Monday, west to southwest flow aloft will move
over the area with warming and drying.  Isolated showers and
thunderstorms will be possible but with much less coverage.
areas of west to southwest winds will spread from west to east
and become gusty. Mixing heights and transport winds will combine
for generally very good to excellent smoke dispersal from  late
morning through early evening each day.

&&

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

&&

$$

SHORT TERM...Baker
LONG TERM...Baker
AVIATION...McDonald
FIRE WEATHER...Baker



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