Area Forecast Discussion
Issued by NWS Riverton, WY

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FXUS65 KRIW 170512
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
1112 PM MDT Fri Jun 16 2017

.SHORT TERM...(This evening through Monday)
Issued at 225 PM MDT Fri Jun 16 2017

Moisture in westerly flow aloft with a short wave low pressure
trough will support scattered showers with isolated thunderstorms
with strong wind gusts and hail this evening. Temperatures will
cool with a cold front behind the trough moving south and east
late tonight and Saturday morning. Showers will decease on
Saturday there will remain a threat of isolated thunderstorms
mainly over the western and northern mountains. Cooling will
continue with most areas in the 40s, mid 20s and 30s mountains,
Sunday morning. Sunday and monday look dry with temperatures
warming Sunday night and Monday with lighter wind as high pressure
builds over the area.

.LONG TERM...(Monday night through Friday)
Issued at 225 PM MDT Fri Jun 16 2017

...Summer like weather ahead...

The weather will start out hot and dry in the extended forecast
for Tuesday and Wednesday as the high over the hot desert
southwest extends a flattening ridge axis north across the rest
of the western United States with the ridge axis remaining to our
west with the ridge axis never quite making it this far east. The
overall trend over the course of next week will be for the large
closed low over Eastern Canada to dig, enhancing the trough over
the Midwest, with this long wave trough retrograding west. This
will encourage each successive shortwave riding up and over the
ridge in Canada, Montana, and the northern Dakotas to track
farther southwest, with time, with each track of each shortwave
tracking ever closer to our CWA with each troughpa to our north
and east. The first wave riding the ridge will take place Monday
night, then one on Wednesday, and then the one with the greatest
impact will be Friday. This will result in a slight gradual
cooling trend during the course of next week until finally we will
see a slight chance of thunderstorms, mainly in the Northern
Mountains Friday afternoon and evening. The high temps will start
out in the low 90s at the lower elevations east of the divide
Tue/Wed and 70s west. Then by Thu/Fri highs in the 80s east and
60s west. However, on Friday we will see upper 70s in our northern
zones east of the divide with the added clouds and isold precip.
The Euro is the slowest with this trend, the GFS the fastest, with
the Canadian not quite on board with this soln, so Will go with
the GFS/Euro blend for the timing of this trend.

&&

.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1110 PM MDT Fri Jun 16 2017

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

Scattered to numerous showers and isolated thunderstorms will continue
across most of the area through 09z before this activity
gradually diminishes. Expect frequent mountain obscurations and
possible brief MVFR conditions at KJAC-KPNA-KBPI. Some clearing
may result in local IFR-LIFR cigs and patchy fog in the same areas
09z-14z. A drier northwest flow will prevail from NW-SE 12z-18z
Saturday with isolated showers lingering over the mountains. VFR
conditions and light wind will prevail Saturday night.

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

An upper level disturbance and associated cold front will continue
to bring scattered showers and a few thunderstorms across the area
through 12z. Some lower MVFR ceilings may follow the front,
mainly down the Interstate 25 corridor, vicinity KBYG-KCPR, 10z-
14z Saturday. A drier NW flow will then prevail late Saturday
morning through the afternoon with gusty surface north wind
10-20kts. Winds will diminish early Saturday evening with VFR
conditions, unlimited ceilings, prevailing Saturday night.

&&

.FIRE WEATHER...
Issued AT 225 PM MDT Fri Jun 16 2017

Moisture in westerly flow aloft with a short wave low pressure
trough will support scattered showers with isolated thunderstorms
with strong wind gusts and hail this evening. Temperatures will
cool with a cold front behind the trough moving south and east
late tonight and Saturday morning. Showers will decease on
Saturday there will remain a threat of isolated thunderstorms
mainly over the western and northern mountains. Cooling will
continue with most areas in the 40s, mid 20s and 30s mountains,
Sunday morning. Sunday and monday look dry with temperatures
warming Sunday night and Monday with lighter wind as high pressure
builds over the area. Sufficient wind and heating will combine
with favorable mixing for good to excellent smoke dispersal in the
afternoons Saturday through Monday.

&&

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

$$

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



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