Area Forecast Discussion
Issued by NWS Riverton, WY

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628
FXUS65 KRIW 222053
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
253 PM MDT Thu Jun 22 2017

.SHORT TERM...(This evening through Sunday)
Issued at 251 PM MDT Thu Jun 22 2017

Cool mostly dry high pressure with northwest flow aloft will limit
showers to the northern mountains through Sunday with a series of
cold fronts from Canada keeping temperatures below normal with
north to northeast winds in the north and west winds across the
far south.

.LONG TERM...(Sunday night through Thursday)
Issued at 251 PM MDT Thu Jun 22 2017

By Sunday night the steering winds will relax as the ridge builds in
from the west and any breezy areas will see diminishing winds. The
long wave ridge over the western United States and the long wave
trough over the east will flatten just a little as a shortwaves
rides up and over the ridge during next week. The GFS is the most
aggressive with this shortwave and the asct closed low tracking east
across Southern Canada next Tuesday and Wednesday. The GFS actually
depicts a lead shortwave on Tuesday with the main troughpa
Wednesday. Then high pressure builds in from the west again by
Thursday. Monday will be a hot and dry day with highs in the 90s at
the lower elevations east of the divide and low 80s west. Then by
Tuesday the steering flow will increase and become increasingly
difluent ahead of the lead shortwave and will result in isold
thunderstorms in Northern Wyoming late Tuesday with the main
shortwave and asct difluent flow giving Northern Wyoming another
round of isold convection late Wednesday. Will favor a blend of the
models and will depict low pops Tue/Wed to cover the uncertainty of
pops for Tuesday as the Canadian and Euro would suggest quieter
weather Tuesday as opposed to the GFS. Tuesday will continue hot
east of the divide ahead of the main shortwave. Highs will then cool
to the 80s Wednesday and 70s Thursday behind the trough and 70s
Wednesday and 60s Thursday out west as h7 temps of 4C move into
Northwest Wyoming by Wednesday morning. Instability appears to be
relatively weak Tue/Wed with much better instability to our east
over the Plains states. West winds will increase Tuesday and
Wednesday ahead of the approaching troughpa. Fire danger will
increase Tuesday and Wednesday, especially east of the divide where
the min RH will dip to the low to upper teens along with that
increase in wind. A for any river flooding, although temps will
increase at the beginning of the week, much of the stored mstr in
the mtns will have been depleted, especially in the Southern Wind
River Mtns by then.
&&

.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 251 PM MDT Thu Jun 22 2017

VFR will prevail at all terminals through 12Z/Fri. A cool front will
bring northerly oriented winds of 15-25kts (with higher gusts) has
pushed south to the divide this morning. Generally few clouds
expected around the forecast area through the period. A second cool
front with gusty northerly winds will again burst through the region
this (Thursday) evening...affecting most terminal sites east of the
Divide. LLWS possible with the frontal passages at some locations.

&&

.FIRE WEATHER...
Issued AT 251 PM MDT Thu Jun 22 2017

Cool mostly dry high pressure with northwest flow aloft will limit
showers to the northern mountains through Sunday with a series of
cold fronts from Canada keeping temperatures below normal with
north to northeast winds in the north and west winds across the
far south.  The air mass should mix out enough in hte lower levels
for good smoke dispersal in the afternoons and early evenings.

&&

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

$$

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



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