Area Forecast Discussion
Issued by NWS Riverton, WY

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FXUS65 KRIW 171852

Area Forecast Discussion
National Weather Service Riverton WY
1252 PM MDT MON OCT 17 2016

.SHORT TERM...Tonight Through Thursday

Impressive storm system blew through last night with a period of
very heavy snow in a narrow ribbon of the southwest with an area
between Daniel and Pinedale receiving 12-15 inches. The main
dynamics with this system are pulling off to the east with a strong
jet overhead. Trapped mountain waves showing up in the west and
strong winds have gradually been spreading into Central Wyoming.
High wind warnings will continue through 6 pm for
Sweetwater/Fremont/Natrona counties. After a brief respite...snow
will return to the west Tuesday morning and increase into the
afternoon as the next shortwave rides in on the next jet streak.
Colder mid levels will lower the snow levels further with the threat
of snow showers east of the divide later Tuesday or Tuesday
night. We may eventually need some winter weather advisories out
west for Tuesday into Tuesday night. When this system moves east
of the divide, the threat of snow showers will increase,
especially near and downwind (se) of the higher terrain. Could
start to see some snow bands forming later Tuesday night into
Wednesday morning from Fremont over to Natrona county as another
sewd moving shortwave interacts with -26c air at h5. h8-h7
convergence may also develop with a wnw wind coming down from
Crowheart and a more n-nw wind from the Bighorn Basin creating a
focus for possible snow shower development. Added in some pops to
start with and we`ll see how it looks again tomorrow. Gradual
clearing Wednesday night with Thursday high and dry (but with a
chilly start). In fact, tonight will be quite chilly for areas
where the wind dies down and in the west that saw significant snow
like the PNA to BPI area. Added in some fog in the too with the
clearing sky and snow cover.

.LONG TERM...Thursday Night Through Monday

Mainly quiet and mild weather looks to be the rule through most of
the long term. Ridging will continue to build across the area on
Friday and bring a nice end to the week with a good deal of
sunshine, mild temperatures and light to moderate winds. A weak cold
front will the move toward the area later on Saturday and into
Sunday and bring a small drop in temperatures for later in the
weekend after a warm day on Saturday when some of the normally
warmer areas could see temperatures climb toward 70. As for the
chance of any precipitation, the front has very little moisture to
work with. In addition, any upper level support will likely remain
to the north. As a result, we kept the forecast dry.

The next decent chance of any showers would be on Monday as the next
system moves in from the south and west. This far out, as one would
expected, there are differences in timing, location and strength of
the system. Other than that, they models are in agreement. Note
sarcasm. With the uncertainty, for now we went with slight POPS out
west and kept areas East of the Divide mainly dry.




Wind should decrease around sunset as winds decouple and should
remain light through around 18Z. In areas that saw substantial
snowfall, especially around KPNA and KBPI, fog could form tonight so
we added vicinity fog to the forecast. The next system will move
across the area from west to east and bring possible MVFR conditions
to many TAF sites along with frequent mountain obscurations.


Any leftover showers should move away by 00z tonight and wind should
decrease as the pressure gradient relaxed and winds decouple after
sunset. Mainly VFR conditions are then expected through 00z with any
showers approaching from the west holding off until after 00Z



Fire danger low to moderate through the early this minimum
RH values remain above 25 percent over those areas in central
Wyoming where fuels remain critical. The strong wind across much of
the area today will decrease this evening. Another system will move
into the west on Tuesday with widespread light to locally moderate
snow expected through Tuesday night. Areas of mixed rain and snow or
snow showers will develop east of the divide Tuesday night and
continue into Wednesday morning. The airmass will dry out and warm
up Thursday into the weekend.


.RIW Watches/Warnings/Advisories...
High Wind Warning until 6 PM MDT this evening for WYZ016>020-



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