Area Forecast Discussion
Issued by NWS Riverton, WY

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FXUS65 KRIW 270452
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
1052 PM MDT Mon Jun 26 2017

.SHORT TERM...(This evening through Thursday)
Issued at 225 PM MDT Mon Jun 26 2017

The high pressure ridge over eastern Idaho will move east as a
Pacific low pressure trough moving into the Pacific Northwest
coast spreading southwest winds across the area tonight and Tuesday.
Temperatures will warm with increasing instability with Scattered
showers and thunderstorms Tuesday.  Relative humidity will be low
with strong gusty winds in the afternoon and evening across the
south.
Showers and thunderstorms will become more widespread Wednesday and
Thursday with some cooling beginning as cloud cover and precipitation
increase. Strong gusty winds will be an increasing threat with
thunderstorms.

.LONG TERM...(Thursday night through Monday)
Issued at 225 PM MDT Mon Jun 26 2017

In wake of the cold front Thursday, an unseasonably cool end to June
is expected Friday with highs about 10 degrees cooler than average
east, and about 5 degrees cooler west. Some energy in the northwest
flow on Friday could result in some convection across the northern
mountains spreading southeast into the basins and valleys. However
instability is weak so expecting any thunderstorms to be quite
isolated. The ECMWF and GFS show a more zonal flow developing this
weekend with relatively weak shortwaves in the flow with the GFS a
bit more amplified. This will keep afternoon/evening thunderstorms
in the forecast across the north and central portions of the area
mainly over the mountains and adjacent foothills, with dry
conditions prevailing over the south. Global models then show a
drier and warmer airmass pushing into the region for the 4th of July
with little or no chance of thunderstorms. However looks like
temperatures will be above average with a westerly breeze.

&&

.AVIATION...(For the 06Z TAFS through 06Z Wednesday)
Issued at 1050 PM MDT Mon Jun 26 2017

Some showers and isolated thunderstorms will occur in the west
overnight into Tuesday morning. Only isolated showers will occur
east of the divide through Tuesday morning. Tuesday afternoon and
evening will see new showers and storms develop over the north half
of the area...roughly north of a line from Jackson to Kaycee. Some
of the storms will produce strong wind gusts and hail. The activity
up north will occur through 06Z Wed. Now south of the Jackson to
Kaycee line, showers and storms will be isolated Tuesday afternoon
and evening. Strong outflow wind gusts will be the main threat from
thunderstorms. Gusty wind will occur at times at some of the
terminal sites. Except for brief IFR/MVFR in some thunderstorms
Tuesday afternoon and evening, VFR conditions are to prevail through
the period.

&&

.FIRE WEATHER...
Issued AT 205 PM MDT Mon Jun 26 2017

The high pressure ridge over eastern Idaho will move east as a
Pacific low pressure trough moving into the Pacific Northwest
coast spreading southwest winds across the area tonight and Tuesday.
Temperatures will warm with increasing instability with Scattered
showers and thunderstorms Tuesday.  Relative humidity will be low
with strong gusty winds in the afternoon and evening across the
south.
Showers and thunderstorms will become more widespread Wednesday and
Thursday with some cooling beginning as cloud cover and precipitation
increase. Strong gusty winds will be an increasing threat with
thunderstorms. The lower air mass will be unstable enough with
sufficient wind for very good to excellent smoke dispersal from late
morning to mid evening each day.

&&

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

$$

SHORT TERM...Baker
LONG TERM...Murrell
AVIATION...AR
FIRE WEATHER...Baker



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