Area Forecast Discussion
Issued by NWS Riverton, WY

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FXUS65 KRIW 252248
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
448 PM MDT Fri May 25 2018

.SHORT TERM...This evening through Monday
Issued at 156 PM MDT Fri May 25 2018

A weak high pressure ridge with southwest flow aloft over the area
will limit moisture and instability supporting isolated to widely
scattered showers and thunderstorms mainly over the mountains this
evening and again on Saturday.  As a Pacific low pressure trough off
of the west coast of California and the Pacific Northwest shifts
slowly east inland, moisture and instability will increase in the
southwest flow Saturday bringing a significant increase in showers
and thunderstorms.  Temperatures will warm through late day Saturday
and then begin to cool Saturday night and Sunday. The warm
temperatures on Saturday will accelerate snow melt runoff with
most rivers and streams expected to rise to near bankfull with
some flooding. Please check on local flood products in your area.
Sunday and Monday significant rainfall of 1 to 2 inches will be
possible adding to flooding concerns.

.LONG TERM...Monday night through Friday
Issued at 156 PM MDT Fri May 25 2018

Lingering moisture and slight instability will result in scattered
showers and thunderstorms over the western mountains and far north
Monday night through Tuesday evening. Upper flow will back SW
Wednesday and Thursday as next Pacific trough moves onto the West
Coast. This will bring a drier and warmer airmass into the area,
with a few afternoon thunderstorms developing over the high terrain
and along favored mountain/valley breeze boundaries.  The impacts of
this next trough remain uncertain at the tail end of the extended
period into next weekend.  The GFS shows a split flow with more of
the same, upper low lifting out of the Great Basin across the area
late Friday-Saturday. ECMWF shows ridge strengthening over the
southern Plains with most of this trough`s energy shearing into the
northern Rockies. Friday the great plains ridge begins to weaken
which will let more and stronger activity into the northwestern
areas.

&&

.AVIATION...For the 18Z TAFS through 18Z Saturday afternoon
Issued at 448 PM MDT Fri May 25 2018

West of the Continental Divide...KJAC/KBPI/KPNA/KRKS

Very isolated showers or storms will occur over the NW WY mountains
after through 03Z. VFR conditions are forecast at the terminal sites
through the period with no VCSH/VCTS expected.

East of the Continental Divide...KCPR/KCOD/KRIW/KLND/KWRL

VFR conditions will occur through the forecast period. Dry weather
is forecast at the terminal sites.

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

&&

.FIRE WEATHER...
Issued AT 156 PM MDT Fri May 25 2018

A weak high pressure ridge with southwest flow aloft over the area
will limit moisture and instability supporting isolated to widely
scattered showers and thunderstorms mainly over the mountains this
evening and again on Saturday.  As a Pacific low pressure trough off
of the west coast of California and the Pacific Northwest shifts
slowly east inland, moisture and instability will increase in the
southwest flow Saturday bringing a significant increase in showers
and thunderstorms.  Temperatures will warm through late day Saturday
and then begin to cool Saturday night and Sunday. The warm
temperatures on Saturday will accelerate snow melt runoff with
most rivers and streams expected to rise to near bankfull with
some flooding. Please check on local flood products in your area.
Sunday and Monday significant rainfall of 1 to 2 inches will be
possible adding to flooding concerns.

&&

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

$$

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



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