Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Riverton Wyoming
242 PM MDT Wednesday Jul 1 2015
Update...added 06z aviation discussion
Short term...tonight through Thursday (issued at 242 PM mdt)
Radar indicating some shower development around the Washakie Needles
this afternoon...with activity streaming eastward and weakening over
The Owl creek mountains and into the Wind River basin.
Additionally...shower activity continues to move across eastern
Sweetwater County where it has been most consistent this
afternoon. The forecast has been updated to reflect this
potential across southern Wyoming. Isolated activity may spread
to include much of the area east of The Divide through this
Shower activity will wane with the loss of daylight this
evening...with widespread dry conditions expected overnight. Another
surge of moisture will bring a few showers and thunderstorms over
the area Thursday afternoon. Most activity is expected to remain
confined to the mountain areas.
Long term...Thursday night through Wednesday
Overall...west-northwest flow aloft will persist over west central
Wyoming. Generally dry and very warm on Friday and for the Fourth of
July...although a few thunderstorms could develop over mountain
ranges during the afternoon hours.
Active northern stream then brings a cold front across Wyoming on
Sunday. Afternoon heating combined with this boundary should result
in scattered afternoon and evening thunderstorms. Could be some
lingering showers especially east of The Divide through Sunday
night...so Sunday and early Monday look to be the wettest days of
Cooler...more stable air then moves into the forecast area Monday
night and Tuesday. Medium range pattern looks to be weak westerly
flow aloft with marginal instability. So after Sunday night...should
be the typical isolated to widely scattered afternoon and evening
thunderstorms for both mountains and basins. Temperatures will be
around normal through the extended period.
Isolated showers and thunderstorms will linger across mainly Natrona
County...vicinity kcpr...through 07z. Otherwise...VFR conditions with
few-scattered fl150-200 will prevail across the area through 18z Thursday.
Surface high pressure to the north will result in an upslope NE-east surface
flow east of The Divide Thursday afternoon. The best moisture and
instability will be along a stationary frontal boundary along the
east slopes of The Divide with widely scattered thunderstorms expected
primarily along a vicinity kcod-klnd line 21z Thursday-04z Friday.
Thunderstorm activity will be more isolated further east behind the
frontal boundary. A dry and more stable airmass will result in
little or no thunderstorm activity west of The Divide on Thursday.
Warm and mostly dry conditions expected through Independence day.
Some isolated showers and thunderstorms will be possible over the
mountain areas each afternoon...which may send some gusty and
erratic wind into the lower elevations. Additional shower and
thunderstorm activity anticipated starting Sunday as more moisture
and instability moves over the area.