Area Forecast Discussion
Issued by NWS Riverton, WY

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FXUS65 KRIW 170456
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
1055 PM MDT SAT JUL 16 2016

.SHORT TERM...Tonight Through Sunday

Rather strong west southwest flow aloft will remain over western and
central Wyoming tonight and Sunday. The moisture in the flow is
rather limited supporting generally isolated showers and
thunderstorms over and near the mountains this afternoon.
Convection will continue in the evening hours and some showers
may linger over then northern mountains over night. Features in
the flow aloft are quite weak with the main polar front to the
north and the monsoon to the south. Little change in temperatures
will result. A weak cold front will move south from Montana across
the northern Big Horn Basin and the eastern plains across Johnson
and Natrona counties making a push into the Wind River Basin over
night. The front will wash out quickly by noon with a return to
southwest winds over much of the area.

.LONG TERM...Sunday night THROUGH Saturday

The flow aloft will shift to the southwest Sunday night as a high
pressure ridge builds north along the eastern border of Wyoming
and a Pacific low pressure trough deepens and begins to move
inland along the West Coast. The northern edge of the monsoon
plume is expected to move north across mainly southern and central
Wyoming in the southwest flow. The better moisture will remain to
the south and east. Isolated to widely scattered showers and
thunderstorms will move through Sunday evening with some showers
lingering over night. Warming is expected with the southwest flow
and the models dry out the flow pushing the monsoon plume to the
east and south, brushing southern Sweetwater county each day through
the extended period. Towards the end of the week the flow will
become more westerly with a Canadian trough moving southeast from
Saskatchewan into the Dakotas. This may push a weak cold front south
from Montana across the north and east Friday evening with slight
cooling in the north and east Saturday morning.

&&

.AVIATION.../06Z ISSUANCE/

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

Mostly clear skies expected overnight except for Sweetwater
county where mid level clouds could bring some light showers to the
KRKS terminal due to a northerly push interacting with southerly
flow.Weak energy then comes up from from the Great Basin early
Sunday afternoon into the early evening hours to generate isolated
to scattered showers and thunderstorms.  Drier air expected to
follow Sunday evening.  VFR conditions thus expected for the next 30
or so hours, except for possible MVFR under and around storms.  Wind
is likely to be erratic and gusty from 18Z Sun though 02Z Mon.
Highest terrain occasionally obscured.

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

A northerly and easterly surge of relatively moist air has moved
into northern and central WY this evening.  Some showers and
isolated thunderstorms are possible just south of KCPR through 08Z
Sun, otherwise VFR conditions expected overnight.  Isolated to
scattered showers and thunderstorms are expected to develop early
Sunday afternoon over SW WY and move northeastward through the
afternoon and evening.  KLND and KCPR appear to me move favorable at
this time. MVFR conditions are possible under and around the
storms,and gusty outflow wind will be erratic as well. The storms
will continue into the late evening hours into northern WY with some
southerly wind following the storms in central WY. Higher terrain
will likely be obscured during the late afternoon and evening on
Sunday.

&&

.FIRE WEATHER...

Rather strong west southwest flow aloft will remain over western
and central Wyoming tonight and Sunday. The air mass will remain
fairly dry with isolated showers and thunderstorms over and near
the mountains through this evening and again Sunday afternoon
and evening. Strong wind gusts to 50 mph will be the main threat
with thunderstorms. Relative humidity will remain low sunday
afternoon.

&&

.RIW Watches/Warnings/Advisories...
Red Flag Warning until 9 PM MDT this evening for WYZ280-300.

&&

$$

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


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