Area Forecast Discussion
Issued by NWS Riverton, WY

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FXUS65 KRIW 161641
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
1041 AM MDT Sun Jul 16 2017

.SHORT TERM...Sunday through Tuesday night
Issued at 220 AM MDT Sun Jul 16 2017

We still have a few showers and thunderstorms out there this
morning. However, most appear to be weakening and should be gone by
sunrise. There will be another round of convection today as well. In
addition, a few of these could turn strong in spots, especially
across the northern border. With the large dew point depressions and
expected high cloud bases, once again the main threat will be strong
wind gusts. However, there is more shear today so this could
tilt updrafts enough so there could be some hail as well across the
north. The culprit for this is another shortwave as well as a cold
front, well, I`d call it a cool front since temperatures shouldn`t
drop too much behind it. Expect another hot day today with
temperatures similar to yesterday. The thunderstorms will be more of
an early show with most over by midnight then mainly dry conditions
after midnight.

Temperatures will cool somewhat for Monday. However, they should
remain near to above normal once again. However, thunderstorms will
once again be on the prowl as another shortwave moves through the
area. Coverage should again be similar to Sunday with again the
strongest storms across the north with the better shear and upper
level support.

Much drier air should move into the area for Tuesday as a ridge axis
builds into the area. This will mean another rise in temperatures.
In addition, the models are much drier with few thunderstorms. Of
course, the GFS is doing it`s usual making the mountains wetter than
the Congo rain forest. For now, we reduced the POPS to isolated but
they may be removed if the trend continues.

.LONG TERM...Wednesday through Sunday
Issued at 220 AM MDT Sun Jul 16 2017

Wednesday will have isolated showers and thunderstorms over the
southwest and south in the afternoon and evening. Lingering
activity in the south may go past midnight. Elsewhere, very
isolated thunderstorm coverage is expected. Thursday will again
have isolated afternoon and evening thunderstorms with a little
better coverage in the south and southwest. Isolated activity in
the south may linger past midnight Thurs night. Friday looks dry
for most areas. Isolated showers and storms over the far south and
some of the mountains. Saturday appears to be dry for most areas.
Isolated storms may occur in the east zones, from the Bighorn
mountains south to Casper mountain. Next Sunday looks dry for most
places with isolated afternoon and evening storms over and near
the mountains. High temperatures will remain very warm to hot
through the period with 80s and 90s, 60s and 70s in the mountains.
A weak cool front could push into the north zones Friday which may
bring a few degrees of cooling Friday and Saturday. GFS model is
cooler than the ECMWF model by a few degrees both days. Will not
get carried away with cooling at this point in the north both
days. Bottom line, the summer pattern will continue and fire
weather concerns will gradually elevate.

&&

.AVIATION...18Z Issuance
Issued at 220 AM MDT Sun Jul 16 2017

VFR conditions will prevail through the forecast period. A cold
front will push southeast across the region this afternoon and
evening. Isolated to widely scattered showers and thunderstorms will
develop a few hours ahead of and then along/near the cold front,
primarily from 19z today until 06z Monday. A few strong
thunderstorms are possible vicinity and north of a KJAC-KBYG line
that may produce small hail and strong wind gusts 40-55 kts. Drier
air and clearing will follow the front east across the area tonight.
Another weak upper level disturbance and associated surface front
will then move across Wyoming after 10Z Monday providing chances for
isolated showers Monday morning along/near/south of a KAFO-KBYG
line.

&&

.FIRE WEATHER...
Issued at 220 AM MDT Sun Jul 16 2017

It will be another warm to hot day across western and Central
Wyoming today. Isolated afternoon thunderstorms will
fire across much of the area as a cold front moves through, with the
strongest storms across the north especially along the Wyoming-
Montana border. Again, any thunderstorm will have the threat of
gusty and erratic outflow winds. Otherwise, wind should remain
light to moderate. Relative humidity will fall to around 15
percent in portions of the Basins East of the Divide. Mixing and
smoke dispersal will be generally good to very good.

&&

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

&&

$$

SHORT TERM...Hattings
LONG TERM...AR
AVIATION...Braun
FIRE WEATHER...Hattings



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