Area Forecast Discussion
Issued by NWS Riverton, WY

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FXUS65 KRIW 190542
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
1142 PM MDT Sun Jun 18 2017

.SHORT TERM...(This evening through Wednesday)
Issued at 230 PM MDT Sun Jun 18 2017

High pressure with west northwest flow aloft will remain over the
area building north from the Great Basin.  As this warmer air moves
north, temperatures will warm over the area with decreasing wind.
Moisture will be limited with isolated light showers possible in the
far north mountains.  Heating by Tuesday will make the air mass
unstable in the afternoon and evening with scattered showers and
isolated thunderstorms possible.  Warming will continue on Wednesday
with increasing instability again in the afternoon and evening for
more showers and thunderstorms.

.LONG TERM...(Wednesday night through Sunday)
Issued at 230 PM MDT Sun Jun 18 2017

Beginning of fcst, lee side troughing induced gusty winds will
persist into the early evening across srn and portions of cntrl WY.
Additionally, the models continue to show a relatively weak fast
moving SW trof zipping across the FA Wednesday night. This feature
along with an associated near stationary front may extend a period
mainly orographically induced afternoon/early evening showers/storms
a bit longer overnight...and perhaps along the front. A couple of
stronger storms will be possible over Johnson county (the usual).

Thursday, zonal to slight nwrly flow aloft continues with somewhat
lower heights...causing temps to fall off a bit. Otherwise, mostly
precipitation free other than a couple of orographically initiated
showers/storms in the afternoon/evening period. Gusty west to
northwest winds across srn/cntrl WY once again...northerly behind
another (or the same) nearly stationary front lying east of the
Divide.

Friday, the rather flat flow aloft now looks like it will be
interrupted earlier than thought before by an upper lvl SW trof
(looked somewhat later 24 hrs ago). Frontogenesis will be ongoing
early in the day to the north over MT...pushing into nrn WY mid-day-
ish along with increasing chances for precipitation along and north
of the front. Cooler with strong gusty north winds behind the front
accompanied by showers and a few embedded thunderstorms into the
evening.

Saturday and Sunday: Post frontal and cooler Saturday. Dry under nw
flow aloft and building high P at the SFC. Sunday also dry at this
point with the high P breaking and lee side low P starting to build
with a return to gusty afternoon west/northwest winds across srn WY.
No significant wx fcst at this time.

&&

.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1140 PM MDT Sun Jun 18 2017

Sct-Bkn FL130-150 vicinity and north of a KJAC-KCPR line at 06z
will continue decrease from the west through 12z. Unlimited
ceilings, VFR conditions will then prevail across the region
through 12z Tuesday. Winds will be light, mainly west through the
wind corridors through the afternoon, with northeast to east winds
developing across much of central Wyoming during Monday evening.

&&

.FIRE WEATHER...
Issued AT 210 PM MDT Sun Jun 18 2017

High pressure with west northwest flow aloft will remain over the
area building north from the Great Basin.  As this warmer air moves
north, temperatures will warm over the area with decreasing wind.
Moisture will be limited with isolated light showers possible in the
far north mountains.  Heating by Tuesday will make the air mass
unstable in the afternoon and evening with scattered showers and
isolated thunderstorms possible.  Warming will continue on Wednesday
with increasing instability again in the afternoon and evening for
more showers and thunderstorms.  The air mass instability combined with
breezy west northwest winds will combine to produce very good to
excellent afternoon smoke dispersal through Wednesday afternoon.

&&

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

$$

SHORT TERM...Baker
LONG TERM...Braun
AVIATION...Meunier
FIRE WEATHER...Baker


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