Area Forecast Discussion
Issued by NWS Riverton, WY

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FXUS65 KRIW 252013
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
213 PM MDT SAT JUN 25 2016

.SHORT TERM...Tonight and Sunday

The ongoing red flag warning across Johnson and Natrona Counties
through 9 PM looks good. The Casper Mountain zone and northern
portion of Johnson County could keep RHs above 15% this afternoon,
but close enough to keep red flag warnings. Although RH will remain
low Sunday, winds will be weaker and no red flag warning will be
needed.

The other main concern tonight is for a light freeze across the
western valleys and basins. The setup is good for strong radiational
cooling with a very dry air mass in place with clear skies and light
winds. Contemplated a freeze warning, but decided to issue an SPS as
the freeze should be on the light side. Having said that some areas
such as Bondurant/Daniel could see a low of 25.  Daniel got down to
28 last night.

Otherwise, a dry westerly flow will occur tonight and Sunday with
mostly clear to clear skies. Temperatures on Sunday will be a few
degrees warmer than what occurred Saturday.

.LONG TERM...Sunday night THROUGH Saturday

We did not make a lot of changes to the long range forecast. Sunday
night looks mainly dry at this point. As for Monday, this looks to
be a dry day as well. The European model has some convection along
the northern border. However, this models has been overdoing
convection. In addition, with 500 millibar heights expected to be
over 5900 meters it will be very difficult to break the cap. As a
result, a dry forecast was left. High temperatures will be fairly
close to seasonal normals with light to moderate winds which should
east fire concerns somewhat.

Things may get a bit more active for Tuesday as the ridge gets
suppressed south a bit and allows for some shortwaves to top the
ridge and possibly produce a better chance of storms. The previous
forecast had from north of a Jackson to Casper line. At this point,
this looks reasonable so we made few changes. Similar conditions are
expected for Wednesday as well. Southwest of this line, with limited
moisture and higher heights dry conditions look to remain the rule.

The models do trend a bit more active for Thursday into the Fourth
of July weekend as heights fall somewhat and a bit more moisture
gets introduced to the area. Most areas look to have a chance of
showers and thunderstorms each day. However, given the uncertainty
in timing of the shortwaves, we kept POPS on the lower side. A vast
majority of the activity at this point looks to be of the afternoon
and evening variety with most areas having a majority of each day
rain free. Temperatures should average fairly close to seasonal
normals.

&&

.AVIATION.../00Z ISSUANCE/

Breezy west to northwest winds ongoing across much of the area will
weaken between 00Z and 03Z. Winds are then expected to remain light
through the remainder of the taf period. Skies are expected to be
mainly SKC.

&&

.FIRE WEATHER...

Dry and warm conditions are expected through Monday. Winds are
expected to be mainly light and terrain driven in most locations.
The exception will be a bit of a westerly breezy over the south
and on the lee side of mountain ranges. Afternoon RH will mainly
be in the teens, and overnight RH recovery will be poor except
across Johnson and Natrona Counties and far western Valleys. A
weak disturbance on Tuesday will give areas along and east of the
Divide a chance of seeing showers and thunderstorms with the best
shot across Johnson County.

&&

.RIW Watches/Warnings/Advisories...
Red Flag Warning until 9 PM MDT this evening for WYZ280-281-285-
300.

&&

$$

SHORT TERM...WM
LONG TERM...Hattings
AVIATION...WM
FIRE WEATHER...WM


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