Area Forecast Discussion
Issued by NWS Riverton, WY

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000
FXUS65 KRIW 260455
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
1055 PM MDT WED MAY 25 2016

.SHORT TERM...Tonight Through Thursday

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 and east 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 continue 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...Thursday Night 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 Wednesday night trough Tuesday. This will
keep cool air over the region with southwest flow bringing Pacific
moisture north and east 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 continue to 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.../06Z Issuance/

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

Shower activity continues to wane this evening, with some
isolated shower activity expected to persist through the
overnight hours over the mountains. Drier conditions anticipated
over the western valleys and basins. Low pressure moving around
the Four Corners area will result in a return of scattered showers
and thunderstorms. VCTS mentioned at the majority of terminals
after 18z. Thunderstorm development is expected to weaken after
03z with the loss of sunlight, with -SHRA remaining possible
through the remainder of the TAF period. Continued activity will
result in additional mountain obscuration in low clouds and shower
activity.

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

Shower activity will weaken through the overnight hours, with
lingering low clouds possible. These low clouds could result in
instances of MVFR conditions, though VFR is more likely through
the overnight hours. The movement of an area of low pressure
through the Four Corners region will result in a return of
showers and thunderstorms after 18z. Thunderstorm activity remains
difficult to pinpoint, with VCTS included at area terminals.
Activity will lose its thunderstorm threat after 03z Friday,
though VCSH will remain possible through the TAF period. Mountain
obscurations will remain possible in lowered ceilings and shower
activity.

&&

.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
and east 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 continue to 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...Branham
FIRE WEATHER...C.Baker


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