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
862
FXUS65 KRIW 171153
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
553 AM MDT Tue Sep 17 2019

.SHORT TERM...(Today and tonight)
Issued at 253 AM MDT Tue Sep 17 2019

Long-anticipated trough beginning to sweep across the
intermountain west this morning, with the center of the trough
currently roughly in far SW ID. Most precipitation is still
sweeping across ID/UT this morning, but a few thunderstorms have
been moving across southwest and central WY overnight. Any
thunderstorms that do pass through this morning will have a threat
for gusty winds, as experienced at LND earlier when winds gusted
up to 73 mph from the outflow from a former shower. Rain will
begin to overspread western WY later this morning as the trough
sweeps east. Models still in agreement with some snowfall across
far western WY and the Wind River range this morning. Still
expecting the trough to very quickly pivot NEWD into SE MT late
this afternoon, with precipitation quickly ending SW to NE through
the afternoon. By 6PM, precipitation should be confined to Johnson
and Big Horn Counties, which will also come to an end quickly
early in the evening. Winds will also be an issue this afternoon
behind the trough. H7 50kt jet streak sweeps across the state.
Good daytime mixing should bring a good amount of this wind down
to the sfc, so widespread gusts of 35 to 40 knots can be expected
through sunset. Much cooler conditions can be expected tonight,
with good radiational cooling allowing temps to drop into the 30s
and 40s under clear skies.

.LONG TERM...(Wednesday through Monday)
Issued at 410 AM MDT Tue Sep 17 2019

Wednesday will be dry, being the day stuck between an exiting and
approaching system. Of note on Wednesday, are gusty winds in the
mountains and the wind corridor from Rock Springs into Natrona
County. Gusts of 35 to 45 mph are currently expected. These same
locations will see breezy to windy conditions every afternoon
through the period. Thursday, the next trough system and cold
front near WY. Both the NAM and GFS show the bulk of
precipitation arriving in the late afternoon and evening hours.
The entire area will have increased precipitation chances from
Thursday night through Saturday. The northwest will see the most
precipitation through that period and Friday will be the wettest
day across the area. Sunday will bring a dry reprieve right before
yet another system impacts the region on Monday.

&&

.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)
Issued at 549 AM MDT Tue Sep 17 2019

A few showers have been passing LND/RIW/RKS overnight with very
gusty winds at times. This portends upcoming conditions today, as
an increase of shower activity arrives with the next weather
system. Shower activity will increase west to east today, with any
showers possibly accompanied by gusty winds greater than 40kts.
Shower activity will end quickly from SW to NE during the
afternoon. Steady southwest winds will increase behind the rain
chances, with areas from RKS to CPR noting winds of 25g40kts at
times later this afternoon. Skies will clear quickly during the
evening, with CLR skies overnight. Winds will relax during the
night, with most areas remaining L/V.

&&

.FIRE WEATHER...
Issued AT 253 AM MDT Tue Sep 17 2019

A cold front will sweep across the region today, keeping
temperatures in the 50s and 60s during the day. This will keep
humidity values higher than the past couple days, with most areas
only falling to 25 to 35 percent during the afternoon. Areas of
zone 280 may still get warm enough for humidity to fall below 20
percent later this afternoon. During the afternoon, behind the
front, southwest winds will increase considerably, with gusts
reaching 30 to 40 mph, especially from RKS to CPR. Some gusts may
reach above 50 mph around any passing showers or thunderstorms,
especially for zone 280.

&&

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

$$

SHORT TERM...Straub
LONG TERM...Bourque
AVIATION...Straub
FIRE WEATHER...Straub



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