Area Forecast Discussion
Issued by NWS Riverton, WY

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS65 KRIW 212040
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
240 PM MDT Sat Apr 21 2018

.SHORT TERM...(This evening through Tuesday)
Issued at 240 PM MDT Sat Apr 21 2018

Dry high pressure surface and aloft will be over the
western mountains tonight and Sunday. A Pacific low pressure
trough will spread clouds and showers, snow above 8800 feet
Sunday night lowering to 8500 feet by late Monday. The last
forecast of the season, and the last of my career, is scheduled
for Sunday afternoon.  Temperatures will warm through Monday
then cool as showers and clouds spread east and a cold front
dives south from Montana. The lower elevations will see mainly rain
with some light snow accumulations Late Monday night and Tuesday
morning as temperatures continue to fall across the area.

.LONG TERM...(Tuesday night through Saturday)
Issued at 240 PM MDT Sat Apr 21 2018

Beginning of forecast: Post frontal will cool/cold overnight temps
and a flattening ridge on its way across the intermountain west. A
large closed/cut-off (COL) low continues spinning off the west coast
over the EPAC. The flattening will be due to a rather large embedded
shortwave trough moving across Canada. The surface will have general
post frontal high pressure across the forecast area with pressure
slowly fall across the northern portion of Wyoming.

Overall, the MR models are out of sorts from the get-go with regard
to the extended portion of the forecast. The EC generally more hard-
line beginning with the embedded shortwave trough, mentioned above,
flattening the ridge and ripping through WY on Thursday while
becoming well out of phase by Thursday night. Waited for the EC to
complete to give some low weight to it as truthfully all models are
having a great deal of trouble solving the closed/cut-off low
riddle over the EPAC. As the kicker approaches Friday night/Saturday
morning, the differing results of the COL exit trajectories per
model are quite different...so some credence will be given to all
through the end of the forecast with low overall confidence to any
one. At least nothing too earth shattering expected to arrive across
the area, through the forecast period.

&&

.AVIATION...(For the 00Z TAFS through 00Z Monday)
Issued at 240 PM MDT Sat Apr 21 2018

VFR conditions to prevail through the forecast period. Winds will
generally be light except for gusty NW winds 10-20 knots at KPNA-
KBPI-KRKS early this evening. Perhaps a few patchy areas of fog will
be possible across the Upper Green River Basin early Sunday morning.

Please see the Aviation Weather Center for the latest information on
icing and turbulence forecasts.

&&

.FIRE WEATHER...
Issued AT 240 PM MDT Sat Apr 21 2018

Dry high pressure surface and aloft will be over the
western mountains tonight and Sunday. A Pacific low pressure
trough will spread clouds and showers, snow above 8800 feet
Sunday night lowering to 8500 feet by late Monday. The last
forecast of the season, and the last of my career, is scheduled
for Sunday afternoon.  Temperatures will warm through Monday
then cool as showers and clouds spread east and a cold front
dives south from Montana. The lower elevations will see mainly rain
with some light snow accumulations Late Monday night and Tuesday
morning as temperatures continue to fall across the area.  Heating
on Sunday and Monday should produce increasing mixing heights
while transport winds will be on the light side.  Most areas will
experience good afternoon smoke dispersal.

&&

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

$$

SHORT TERM...Baker
LONG TERM...Braun
AVIATION...Braun
FIRE WEATHER...Baker


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.