Area Forecast Discussion
Issued by NWS Riverton, WY

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FXUS65 KRIW 140912

Area Forecast Discussion
National Weather Service Riverton WY
312 AM MDT Fri Jul 14 2017

.SHORT TERM...Friday through Sunday night
Issued at 300 AM MDT Fri Jul 14 2017

We did not make a lot of changes to continuity today as it looked
reasonable. Most showers have ended at this time and mainly dry
weather should continue through the morning. All in all, today looks
fairly similar to yesterday. Heights are quite high today and with a
decent cap over the area, it will take some time for any convection
to develop. The best chance will again be near the mountains and
adjacent foothills although many areas will have at least a slight
chance. However, emphasis is on slight since most areas will not a
shower or storm. Once again, the threat of gusty outflow winds will
be the threat with the large dewpoint depressions. Look for another
day of hot temperatures, with some areas in the Bighorn Basin
pushing the century mark. Fire weather concerns should remain below
critical since wind will be light outside of any shower or

At this point, Saturday looks similar to Friday with above normal
temperatures and isolated showers and thunderstorms. Heights do fall
a bit and mid level temperatures cool a bit, but probably not enough
to have a big impact on coverage of thunderstorms. There could be a
better chance for Sunday however as a weak cold front and shortwave
approach the area and increase instability a bit. Again, the main
threat will be strong outflow winds although some small hail may
occur in the far northwest where lift will be a bit better.
Temperatures may cool a bit Sunday with increased cloud cover but
probably not enough to be noticeable.

.LONG TERM...Monday through Friday
Issued at 300 AM MDT Fri Jul 14 2017

Typical summer weather pattern to continue Monday through
Friday. Very warm to hot temperatures through the week with 80s
and 90s...mid 60s and 70s in the mountains. The main forecast
challenge is the amount of shower and thunderstorm coverage each
afternoon and evening. The GFS and ECMWF models bring more mid and
upper level moisture around the upper high in a southwest flow
aloft. 700MB and 500MB temps do not change much through the week
and this warm cap will be a factor in coverage and intensity of
storms that do form. Precipitable water values show an increase
Wed through Fri which, if correct, would aid in getting better
rain. The forecast will have isolated to widely scattered shower
and thunderstorm coverage in the 18Z to 06Z timeframe. Less
activity from 06Z to 18Z. Will have to watch for moisture surges
and weather disturbances rotating around the western side of the
upper high in the coming days and refine forecast as needed.


.AVIATION...12Z Issuance
Issued at 300 AM MDT Fri Jul 14 2017

VFR conditions will occur through the period.  Increasing mid and
high level moisture combined with slight instability will result in
isolated showers and thunderstorms developing over and vicinity of
the mountains primarily from 21z Friday until 03z Saturday.  Weak
flow aloft will keep these storms mostly anchored near the higher
terrain.  KRIW and KWRL were left with no VCTS, while all other
terminals closer to the mountains have VCTS in the forecast.  The
primary hazard will be erratic outflow wind gusts 30-40 knots.  Most
of this activity should dissipate shortly after sunset Friday


Issued at 300 AM MDT Fri Jul 14 2017

Today looks to be a similar day to Thursday. High pressure will
bring another warm to hot day across the area. Relative humidity
will fall to under 15 percent in some of the Basins East of the
Divide as well as Sweetwater County. However, critical fire
conditions are not expected since winds will remain light to
moderate for the most part. Isolated thunderstorms are possible this
afternoon and evening, with erratic wind the main threat from any
storm. Mixing and smoke dispersal will be generally good to very
good. Expect similar conditions on Saturday.





SHORT TERM...Hattings
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