Area Forecast Discussion
Issued by NWS Riverton, WY

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FXUS65 KRIW 141814
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
1214 PM MDT Mon May 14 2018

.SHORT TERM...Monday through Wednesday night

There are still a few showers and a stray thunderstorm out there
tonight. The models do show this fairly decently as well. As for
today, a weak shortwave moving across the area could touch of a few
showers this morning across Natrona and southern Johnson Counties.
The models show this fairly well so we went with it. As for the rest
of the day, things look fairly similar to Sunday with a mix of
clouds and sunshine along with mainly afternoon and evening
thunderstorms. At this time, not much chance for severe weather.
However, again, much like yesterday, we have cool temperatures and
low wet bulb zero levels. This could lead to having small hail in
any thunderstorm and it could cover the ground if a storm persists
long enough. These storms should end by around midnight with mainly
dry conditions late at night.

Thunderstorm coverage should be smaller on Tuesday. This also looks
to be the least active day of the next three as heights rise
somewhat as the upper level low continues to slowly fill. There will
still be a few around, but most areas will likely not see one. The
best chance would be across the western mountains. Temperatures will
also be on a warming trend, with highs likely about 5 to 10 degrees
warmer than on Monday. By Wednesday, a weak shortwave will move
across northern portions of the state. This will likely increase the
coverage of showers and thunderstorms somewhat, especially across
northern and western Wyoming. This also looks to be the warmest day
of the week with some of the lower elevations seeing high
temperatures in the 80s. Winds will also increase somewhat with the
passage of the shortwave, especially across the southwestern Wind
Corridor.

.LONG TERM...Thursday through Monday

Medium range models show an upper low over Nevada at 12Z Thursday.
This feature is expected to push slowly east/east northeast into
N Utah or extreme SE Idaho by around 12Z Friday. Models are
trending for this low to become disorganized Friday into Friday
night before it jumps the Divide. The 00Z GFS shows an upper low
forming across northeast Colorado Saturday while the ECMWF is
showing more of an open wave quickly pulling into the Plains
Saturday as it is picked up by a northern stream trough. This
northern stream trough should send a cold front through much of
the forecast area Friday/Friday evening. This cold front in
combination with the aforementioned southern stream upper low will
give a good shot of precipitation pulling across the area from
north to south across the area Friday/Friday night with the
widespread precipitation ending Saturday morning. Right now, the
disorganization of this system, and limited Gulf of Mexico
moisture due the progged low-mid level flow will limit the
potential for widespread heavy precipitation amounts (i.e., storm
system last weekend). Snow levels are expected to dip down to
around 7000 feet by 12Z Saturday. In wake of this system, mainly
diurnal convection Sunday and Monday is expected mainly on the lee
side of mountains and adjacent foothills.

Temperatures are expected to be about 10 degrees above average
Thursday. Below average temps Saturday in wake of the cold front
Friday/Friday night especially east of the Divide. Warming
temperatures are expected early next week with temps 5-10 degrees
above average by Monday.

&&

.AVIATION...For the 18Z TAFS through 18Z Tuesday

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

Scattered showers and isolated thunderstorms will develop after 20Z
in the west and occur through about 03Z. Local MVFR conditions will
occur with thunderstorms. Mountains will be obscured at times.

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

Scattered showers and isolated thunderstorms will develop after 20Z
and continue through 05Z. MVFR conditions will occur with
thunderstorms. Mountains will be obscured at times. KWRL will be the
exception with most activity staying away from this area which will
allow for VFR conditions at this terminal.

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

&&

.FIRE WEATHER...

Fire concerns should remain low today. A persistent, slow moving
weather system will keep unsettled weather with a mix of clouds and
sun along with isolated to widely scattered showers and
thunderstorms in the forecast, most numerous in the afternoon and
evening. Relative humidity will remain above critical levels with
wind generally light to moderate except in and around any shower or
thunderstorm. Mixing and smoke dispersal will be generally fair to
good.

&&

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

&&

$$

SHORT TERM...Hattings
LONG TERM...Murrell
AVIATION...Hulme
FIRE WEATHER...Hattings



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