Area Forecast Discussion
Issued by NWS Riverton, WY
FXUS65 KRIW 191723
Area Forecast Discussion
National Weather Service Riverton WY
1123 AM MDT FRI AUG 19 2016
.SHORT TERM...Today Through Sunday Night
Another cold front will push through northeastern Wyoming today,
bring a further push of colder temperatures and shower activity for
areas east of the Continental Divide. Models are not demonstrating
significant instability with activity today, with models showing
very limited CAPE and positive Lifted Index values across the area.
However, little pockets of instability are hinted at in model
solutions, so have included some isolated thunderstorms in the early
afternoon hours. However, as the front progresses, the threat of
thunderstorm activity wanes significantly. Temperatures will drop to
values well below normal as the front progresses today.
Shower activity will slide southeast through the late afternoon and
evening hours, with a drier northwest flow developing. A few showers
will linger through around midnight tonight, with shower activity
then ending. This dry northwest flow will remain over the area
through the remainder of the weekend with dry conditions
anticipated. This flow will also help to bring more seasonal
temperatures across the area, with a warming trend beginning on
Saturday for western and central Wyoming.
.LONG TERM...Monday Through Friday
On Monday and Tuesday, the forecast area will be in a mainly dry
westerly flow between a strong upper low pushing east across
south-central Canada, and a weak wave pushing across the Great
Basin/Southern Rockies. A mainly dry cold front is expected to
push south, east of the Divide Tuesday. The main concern will be
elevated to possibly extreme fire weather conditions over the
central and southern areas.
A more potent cold front is progged to push south into the area
Wednesday, and remain across the area through Friday with surface
high pressure over the Plains, and a surface low across the Great
Basin. Aloft a moist northwest flow is expected with the best
moisture along and east of the Divide. The front and better
moisture should result in at least diurnal convection each day
especially east of the Divide.
Temperatures will be above average Monday and Tuesday. Wednesday
through Friday appear to be below average east and seasonal west.
West of the Continental Divide...KJAC/KBPI/KPNA/KRKS
Scattered rain and snow showers along with areas mtn obscuration
will occur in the mountains along the continental divide through
22z. Conditions will improve from northwest to southeast along the
continental divide through 03z this evening. Most of Sweetwater
county will see a gusty northeast wind this afternoon into the
evening hours as the cold front backs westward into southwest WY.
Wind speeds will decrease around 06z Sat. Patchy late night and
morning valley fog will be possible Saturday, including KJAC.
Otherwise, VFR and dry conditions will prevail Saturday.
East of the Continental Divide...KCOD/KCPR/KLND/KRIW/KWRL
A weather system and cold front will continue to bring areas of
showers and isolated thunderstorms with mtn obscuration and areas of
mvfr conditions in the lower elevations due to low clouds and ocnl
heavier showers. The showers will gradually end from north to south
by 00z. In Central WY conditions will gradually improve toward 00z
with VFR conditions prevailing by 03z in most locations. The
exception may be KCPR where lower clouds hang on until 06z Sat.
Except for patchy fog Saturday morning, VFR and dry conditions will