Area Forecast Discussion
Issued by NWS Riverton, WY

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FXUS65 KRIW 210741

Area Forecast Discussion
National Weather Service Riverton WY
141 AM MDT Fri Jul 21 2017

.SHORT TERM...Friday through Sunday night

The weather should be entering into a quieter pattern for the next
few days. A cold front and trough moving through the area that
brought the showers and thunderstorms will continue to sag to the
south and east. There are still some showers and thunderstorms out
there early this morning across Sweetwater County, however, coverage
continues to shrink early this morning. And, this will continue to
be the focus for some isolated showers and thunderstorms today with
some leftover monsoonal moisture hanging around. However, coverage
will be much less than today with rainfall amounts much less as
well. Around the northern two thirds of the state should be dry
today with lowering humidity through the day. Temperatures will be
cooler than yesterday as well, around 5 degrees cooler in most
locations. As for possible, fire danger there will be some gusty
winds around Johnson County. However, the strongest winds and lowest
humidity will probably not line up so no fire weather highlights are
expected. Friday`s thunderstorms will end around midnight.

Mainly dry conditions for all areas are then expected for the
weekend. Ridging will be build across the state and monsoonal
moisture will get shunted to the south of the state. The result will
be a sunny to partly cloudy sky. In addition, temperatures will be
on the rise once again with high temperatures again climbing into
the 80s and 90s across most of the lower elevations.

.LONG TERM...Monday through Friday

Overview...Monsoonal moisture will make a gradual return to the area
early next week with Tuesday and Wednesday expected to be the most
active days for thunderstorms across the area.  A drier westerly
flow is expected by Friday.

Discussion...Synoptic pattern at the outset on Monday features upper
low moving across central Canada over the top of upper ridge across
the Rockies.  Most monsoonal moisture will remain suppressed to the
south, but kept the idea of isolated thunderstorms across the west
and north with GFS showing some weak perturbations rotating across
the area, ECMWF is dry.  Monday will be the warmest day of the
period with central basin highs in the 90s, mostly 80s across the
western valleys.  Upper high is expected to shift slightly east into
the southern High Plains on Tuesday and Wednesday, allowing
monsoonal moisture to rotate northward across the area with the best
moisture and instability, thunderstorm coverage, expected around the
periphery of the upper high across western and northern Wyoming.
Another upper low is expected to progress east across western and
central Canada Thursday and Friday that is expected to suppress
monsoonal moisture further south and set up a sharper lee side
surface trough across the northern High Plains.  Most of the area is
expected to be on the dry side of this surface trough by Friday.


.AVIATION...12Z Issuance

VFR conditions will continue through the forecast period. Have
made some slight changes to wind shift timing at several of the
TAF sites and have made some adjustments to the lowering of wind
speeds toward the end of the forecast for the TAF sites.


Expect drier conditions across the area today following the passage
of a cold front. The exception will be across Sweetwater County
where some lingering moisture will bring isolated showers and
thunderstorms, most numerous south of Interstate 80. A gusty wind
will blow across Johnson County at times this morning. However, wind
should decrease this afternoon so critical fire weather is not
expected. Relative humidity will fall to around 15 percent at times
in the lower elevations this afternoon. Wind should remain light to
moderate elsewhere. Mixing and smoke dispersal will range from fair
in some of the basins to excellent in the south.



SHORT TERM...Hattings
LONG TERM...Meunier
FIRE WEATHER...Hattings is the U.S. government's official web portal to all federal, state and local government web resources and services.