Area Forecast Discussion
Issued by NWS Riverton, WY

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500
FXUS65 KRIW 242010
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
210 PM MDT TUE MAY 24 2016

.Short Term...Tonight Through Wednesday

A major long wave low pressure trough extending from the eastern
Pacific off of the west coast to the eastern great plains will
remain over the region. This will keep cool air over the region
with southwest flow bringing Pacific moisture north along with
instability and jet dynamics supporting shower activity with
embedded afternoon and evening thunderstorms. Thunderstorms will
have small hail...heavy rain and strong wind gusts. Gusty
southwest winds will extend across the lower elevations of the
Red Desert...Wind River and Bighorn basins and Fremont...Natrona
and Johnson counties. Night time freezing to near freezing
temperatures in the mountains will retard the snowmelt. The snow
level will continue to fluctuate between 9000 feet and 7500 feet
day to night. Above 9000 feet accumulations of 2 to 4 inches a
day is expected. Some accumulation may occur below 9000 feet down
to around 8000 feet. Showers and thunderstorms will produce daily
precipitation from .25 to .5 of an inch with local 1 inch amounts.

.Long Term...Wednesday Night Through Tuesday

A major long wave low pressure trough extending from the eastern
Pacific off of the west coast to the eastern great plains will
remain over the region Wednesday night trough Tuesday. This will
keep cool air over the region with southwest flow bringing Pacific
moisture north along with instability and jet dynamics supporting
shower activity with embedded afternoon and evening thunderstorms.
Thunderstorms will have small hail...heavy rain and strong wind
gusts. Gusty southwest winds will extend across the lower
elevations of the Red Desert...Wind River and Bighorn basins and
Fremont...Natrona and Johnson counties. Night time freezing to
near freezing temperatures in the mountains will retard the
snowmelt. The snow level will continue to fluctuate between 9000
feet and 7500 feet day to night. Above 9000 feet accumulations of
2 to 4 inches a day is expected through the week. Some
accumulation may occur below 9000 feet down to around 8000 feet.
Showers and thunderstorms will produce daily precipitation from
.25 to .5 of an inch with local 1 inch amounts. The extended
models start to diverge over the weekend and spread apart more
Monday and tuesday with speed...strength and location of short
wave low pressure troughs.

&&

.AVIATION.../00Z ISSUANCE/

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

A disturbance moving northeast across the region will keep scattered
showers and thunderstorms through the evening...more numerous in the
high country. Brief MVFR conditions in lower ceilings will occur in
and near heavier showers and storms. Wind gusts of 35-45 kts are
possible near stronger or higher based storms. Most activity will
decrease by 04z Wed...lingering a bit longer near KJAC. Early
morning low stratus and MVFR ceilings or VCFG return to some
terminals after 09z. Another round of light showers will return to
the southwest by morning. Another round of showers and thunderstorms
will develop Wednesday afternoon.


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

A strong disturbance moving across the region will keep scattered
showers and thunderstorms east of the divide through the
evening...with periods of brief MVFR conditions in lower ceilings in
and near heavier showers and storms. More numerous and stronger
thunderstorms are possible in both Natrona and Johnson counties
later this afternoon and evening with some storms producing winds
gusts in excess of 45 knots...hail from one half inch to one
inch...and brief heavy rain with frequent lightning. This activity
will decrease from south to north after 04z Wed. Early morning low
stratus and MVFR ceilings or VCFG returns to some terminals after
09z. Light showers will be possible again Wednesday morning with
building afternoon thunderstorms once again.


&&

.FIRE WEATHER...

A major long wave low pressure trough extending from the eastern
Pacific off of the west coast to the eastern great plains will
remain over the region into the weekend.  This will keep cool air
over the region with southwest flow bringing Pacific moisture north
along with instability and jet dynamics supporting shower activity
with embedded afternoon and evening thunderstorms. Thunderstorms
will have small hail...heavy rain and strong wind gusts. Over
the mountains...relative humidity will be elevated with lower
relative humidity and gusty southwest winds across the lower
elevations of the Red Desert...Wind River and Bighorn basins and
Fremont...Natrona and Johnson counties. Night time freezing to
near freezing temperatures in the mountains will retard the
snowmelt. The snow level will continue to fluctuate between 9000
feet and 7500 feet day to night. Above 9000 feet accumulations of
2 to 4 inches a day is expected through the week. Some
accumulation may occur below 9000 feet down to around 8000 feet.
Showers and thunderstorms will produce daily precipitation from
.25 to .5 of an inch with local 1 inch amounts. Outside of areas
of precipitation...mixing heights should rise high enough for good
to very good smoke dispersal in the afternoons.

&&

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

$$

SHORT TERM...C.Baker
LONG TERM...C.Baker
AVIATION...Skrbac
FIRE WEATHER...C.Baker



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