Area Forecast Discussion
Issued by NWS Riverton, WY

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FXUS65 KRIW 300456
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
1056 PM MDT Sat Apr 29 2017

.SHORT TERM...(This evening through Tuesday)
Issued at 206 PM MDT Sat Apr 29 2017

Cold northerly flow will bring drying with some light
snow showers lingering over the mountains tonight and Sunday.
Moisture will increase Sunday afternoon in the west with
increasing snow showers over the western mountains. Sunday night
the showers will spread across the north into the Bighorn
mountains. West winds will pick up across the south Sunday night
and Monday while cool air will continue to move south from Montana
across the north and east. The flow aloft across the north and
west will remain cool and moist with snow showers continuing
across the mountains Tuesday. Some rain and snow showers will
spread south across the lower elevations east of the Continental
Divide. Cool temperatures will result in overall low snowmelt over
the mountains while snow below 6000 feet melts.

.LONG TERM...(Tuesday night through Saturday)
Issued at 206 PM MDT Sat Apr 29 2017

THE SOUTHEAST BOUND AMPLIFYING SHORTWAVE TROUGH AXIS SHOULD BE RIGHT
OVER CENTRAL WYOMING AT OR A LITTLE BIT AFTER 00Z WEDNESDAY. WITH
THE ASCT LEFT FRONT QUAD ON THE BACK SIDE OF THE TROUGH OVERHEAD AND
QG FORCING STILL AIDING IN LIFT IN THE EASTERN ZONES, MOUNTAIN SNOW
AND VALLEY RAIN AND SNOW SHOWERS SHOULD BE FAIRLY WIDESPREAD,
ESPECIALLY TUESDAY EVENING BETWEEN 00Z AND 06Z. WITH THE STREAM OF
VORT LOBES TRACKING SSE ALONG THE IDAHO AND WYOMING BORDER, THE EAST
SLOPE OF THE WIND RIVER MTNS AND THE ADJACENT LANDER FOOTHILLS
SHOULD SEE SOME SIGNIFICANT PRECIP ONCE AGAIN AS THIS AREA FAVORS
THIS PARTICULAR WX PATTERN. SNOW LEVELS SHOULD REACH THE VALLEY AND
BASIN FLOORS, AT LEAST BRIEFLY, JUST BEFORE MIDNIGHT BEFORE THE
PRECIP EXITS TO THE SOUTHEAST WITH H7 TEMPS DROPPING TO BETWEEN -6C
AND -7C BEHIND THIS SHORTWAVE. THEN ON WEDNESDAY, THE STRONGEST
RIDGE THAT WE HAVE SEEN IN A WHILE WILL BE PUSHING EAST INTO THE
CWA. UNDER MOSTLY SUNNY SKIES WE SHOULD WITNESS HIGHS IN THE 50S AT
THE LOWER ELEVATIONS BOTH EAST AND WEST OF THE DIVIDE. THEN ON
THURSDAY AND FRIDAY, HIGHS SHOULD RANGE FROM THE 60S WEST TO THE 70S
AND EVEN SOME LOW 80S FRIDAY IN THE BIG HORN BASIN. THEN BY
SATURDAY, ENOUGH INSTABILITY AND MOISTURE WILL STREAM NNE FROM THE
BASE OF THE NEXT TROUGH ALIGNED ALONG THE PACIFIC STATES. THE
CANADIAN APPEARS TO BRING THIS NEXT TROUGH INLAND THE QUICKEST. FOR
NOW AM KEEPING THE IDEA OF SHOWERS MOVING INTO WESTERN WYOMING
SATURDAY AFTERNOON.

&&

.AVIATION...(For the 06Z TAFS through 06Z Monday)
Issued at 1055 PM MDT Sat Apr 29 2017

WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS Terminals

VFR conditions will occur at most of the terminal sites through 06Z
Monday. Rain and mountain snow showers will develop over NW WY
Sunday after 19Z and continue into Sunday night. Expect some
mountain obscuration and MVFR to IFR conditions in the mountains. At
KJAC airport, VFR conditions will prevail through 00Z, then VCSH
will be in the terminal forecast through 06Z Monday with the
potential for MVFR ceilings.

EAST OF THE DIVIDE...KCOD/KCPR/KLND/KRIW/KWRL Terminals

Patchy fog should form in the Wind River Basin overnight with local
MVFR/IFR conditions. Otherwise VFR conditions will occur through 06Z
Monday. Snow showers will develop in the Northern WY mountains
around 00Z Monday and continue through 06Z Monday. Expect some
mountain obscuration and local MVFR conditions.

&&

.FIRE WEATHER...
Issued AT 206 PM MDT Sat Apr 29 2017

Cold northerly flow will bring drying with some light
snow showers lingering over the mountains tonight and Sunday.
Moisture will increase Sunday afternoon in the west with
increasing snow showers over the western mountains. Sunday night
the showers will spread across the north into the Bighorn
mountains. West winds will pick up across the south Sunday night
and Monday while cool air will continue to move south from Montana
across the north and east. The flow aloft across the north and
west will remain cool and moist with snow showers continuing
across the mountains Tuesday. Some rain and snow showers will
spread south across the lower elevations east of the Continental
Divide. Cool temperatures will result in overall low snowmelt over
the mountains while snow below 6000 feet melts. Marginal mixing
with brisk winds over and near the mountains will produce fair to
low end good afternoon smoke dispersal Sunday and Monday. With
increased low clouds and showers on Tuesday generally poor smoke
dispersal is expected.

&&

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

&&

$$

SHORT TERM...Baker
LONG TERM...Lipson
AVIATION...AR
FIRE WEATHER...Baker


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