Area Forecast Discussion
Issued by NWS Riverton, WY

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FXUS65 KRIW 200847

Area Forecast Discussion
National Weather Service Riverton WY
247 AM MDT FRI MAY 20 2016

.Short Term...Friday through Sunday night

Unsettled will be the word of the weather for the next few days as
an upper level low takes up residence to the west and sends a few
waves of energy over the area. Some showers are still ongoing this
morning but most are rather light at this time. As for lightning,
most has gone away with only an isolated strike or two. There should
be a general waning in coverage through the night with most areas
mainly dry for Friday morning.

The break will be brief through as more showers and thunderstorms
fire up this afternoon. The lion`s share will be West of the Divide.
but one or two could pop up in the eastern mountains and possibly
drift into the adjacent foothills. The most noticeable feature east
of the divide will be wind today as the pressure gradient begins to
tighten ahead of an approaching cold front. At this point, 700
millibar winds do not look strong enough to warrant high wind wind
highlights. However, it will be quite windy this afternoon for many
areas with gusts over 40 mph certainly possible for many areas.
These winds should decrease a bit tonight as the winds decouple with
the loss of mixing this evening although it will still be breezy at

There will be one more warm and windy day ahead of the front on
Saturday. However, things could get more interesting in the
convection department. Model soundings are showing a decent amount
of shear. This, in addition to the added forcing from the passing
cold front could bring some stronger storms. The best threat for
these would be further east where more CAPE and instability will be
found. The Storm Prediction Center has Johnson and Natrona County
under a marginal risk with a slight risk just to the
east.Hightemperatures could be tricky though depending on the
passage of the front. Precipitation should taper off and
temperatures fall behind the front Saturday night.

As for Sunday look for a cooler day with less wind, although still
breezy. With the low heights still around and another shortwave
moving through the area there will once again be the threat of
afternoon convection. With the cooler conditions and lower wet bulb
zero temperatures...small hail may be the main threat with these

.LONG TERM...Monday through Friday

This forecast period will feature an overall trough pattern over
the Rocky Mountain region. A series of weather disturbances will
move through this flow during the week. The given long range
models have various timing of these weather systems as they move
through the area. It appears that convection will be the issue
each afternoon and night with lingering late night/morning
showers. Instability and lapse rates support the daily rounds of
showers and storms. Thus the forecast will have the chance for
showers and storms each day with varying coverage. Surface
convergence areas will certainly occur which will enhance
convection in those locations. 700mb temps and 500mb temps are on
the cool side for the most part during the week and do not
fluctuate much from day to day. Thus not a lot of day to day
changes in highs and lows over the region Mon through Fri.



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

Some patchy fog may follow last night`s showers through 14z,
partially obscuring terrain. Scattered to numerous showers and
isolated thunderstorms will redevelop south to north along and west
of the divide Saturday afternoon with mountain obscurations
increasing with local MVFR conditions possible at KJAC, KBPI and
KPNA.  This activity will diminish in the late evening and overnight
Friday night.

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

Isolated to scattered showers across central Wyoming will gradually
dissipate by sunrise.  South winds will increase to 20-30 knots
across much of the area Friday afternoon.  A few strong
thunderstorms with large hail and damaging winds will be possible
along and north of Interstate 90 Friday afternoon and evening.
Otherwise, isolated showers and thunderstorms will be high-based
across most of central Wyoming with the main hazard of strong
erratic wind gusts over 40 knots.  Winds will diminish Friday
evening and drier air will result in showers dissipating and some
clearing overnight.



After a break this morning, more showers and thunderstorms will fire
this afternoon mainly west of the Divide and across the higher
elevations. Erratic winds from these thunderstorms will be possible.
Across the lower elevations east of the Divide, gusty southwest
winds will develop in the afternoon and continue into the evening.
Mixing and smoke dispersal will be good to excellent after any
morning inversions break. A cold front will move across the state on
Saturday with another chance of showers and thunderstorms.


.RIW Watches/Warnings/Advisories...None.



SHORT TERM...Hattings
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