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
000
FXUS65 KRIW 282217
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
417 PM MDT SAT MAY 28 2016

.SHORT TERM...TONIGHT THROUGH TUESDAY

A cold front has dropped across northern Wyoming today and is
currently draped across Johnson County. Behind the front, a broken
stratocumulus cloud deck is blanketing northern johnson County
where relatively stable conditions exist along with cooler
temperatures, although the temperature has managed to rise from 57 to
62 degrees in BYG over the past hour or so. The thunderstorms
that formed ahead of the front over Natrona county have long since
exited to the east of the cwa with more stable conditions in place
as The front glanced that area. It is possible that the
atmosphere could destabilizize once again before we call it a day
for more isolated activty through early this evening.

Sunday will be the warmest and driest day during the short term as
a flat ridge builds into the area. The only showers or
thunderstorms that will probably form will be over the southwest
where better moisture will work into the area from the west as it
bisects the best instability which will be west of the divide.
Drier air will be working east into northern and central Wyoming.

Then on Monday, the same closed low over British Columbia that
ejected the shortwave east and drove the cold front across our
northern zones this morning will eject another shorwave east
along the Canadian border and will close off over Montana, much
like the other closed low did to our north this past week. It
appears that we could experience a relatively early show of
shower and thunderstorm activity Monday with the approach of the
associated trough/cold front with this weather feature...mainly
across the north before drier air works its way in from the
west...decreasing the magnitude of any convection west of the so
called dry line with this dry line encouraging the early day
convection over the eastern most zones. Then colder air will wrap
around the back side of the Montana low, potentailly dropping the
snow levels down to 6500 feet over northern Wyoming by Tuesday
morning and 8000 feet over central Wyoming including the Wind
River Mountains and Casper Mountain just before the majority of
the shower activity comes to an end. Then for the balance of the
day on Tuesday, we can expect a relatively cool showery
day...especially over the east half of the cwa, east of the
divide with the influence of the wrap around and associated
instability drifting to the east during the afternoon with the
exiting low.


.LONG TERM...TUESDAY NIGHT THROUGH SATURDAY

Upper low will be moving away through the Northern High Plains at
the start of the medium range period. Mean ridge will then slowly
develop over the area into midweek, holding through the weekend.
A few showers and higher mtn snow will linger into Tuesday evening
before tapering off overnight. As the system moves off Tuesday
night, It could be a chilly start to the day Wednesday with most
areas out west below freezing and possibly the Casper area over to
the low lying areas in the Wind River Basin. As ridge builds in,
temperatures warm considerably Wednesday through at least Friday
before leveling off Saturday. It still looks like some ripples will
drop down the front side of the building ridge leading to at least a
chance of some mtn and down wind sites seeing some mainly late day
showers and thunderstorms. Temperatures start out mainly in the 60s
across the lower elevations Wednesday with 40s and 50s in the high
country. By Friday, as h7 temps soar to 10c or even as warm as 12-
13c on the warmer gfs, we will see upper 70s to mid 80s east of the
divide with mainly 70s west and 50s and 60s in the high country. No
doubt this will get the rivers rising once again around here as the
week progresses.

&&

.AVIATION.../00Z ISSUANCE/

West of the Continental Divide...KJAC/KRKS/KPNA/KBPI Routes

Isolated showers and thunderstorms will prevail across the area into
this evening. The strongest storms could have brief heavy rain,
small hail and wind gusts over 40 mph through 04z. Only a few higher
mountain showers may continue overnight. Overall, Saturday will be
drier with most areas dry. Only a few mainly mountain showers or a
brief thunderstorm are possible Saturday afternoon.

East of the Continental Divide...KCPR/KCOD/KRIW/KWRL/KLND Routes

Isolated shower and thunderstorm activity will prevail through 04z.
Isolated light rain showers may persist through 06z. Saturday will
be dry for most of the lower elevations with Johnson County being
the main exception as a cold front brings a little better chance of
afternoon showers and thunderstorms.

&&

.FIRE WEATHER...

Fire danger low THROUGH EARLY NEXT WEEK as green-up and
seasonally elevated humidity levels continue across Wyoming.
MAINLY ISOLATED SHOWERS ALONG WITH A POSSIBLE THUNDERSTORM ARE
EXPECTED THIS EVENING, ESPECIALLY IN THE SOUTHEAST ZONES. Sunday
will see the warmest temperatures of the weekend with a few
locations in the Wind River and Bighorn Basins seeing RH values
drop into the the upper teens (percent). Winds across the entire
forecast area will be on the light side. COOLER WEATHER IS
EXPECTED EARLY NEXT WEEK WITH SHOWERS AND THUNDERSTORMS EXPECTED,
MORE SO IN THE NORTH WHERE SNOW LEVELS COULD BRIEFLY DROP AS LOW
AS 6500 FEET. MUCH WARMER AND DRIER WEATHER IS EXPECTED FOR THE SECOND
HALF OF THE WEEK.

&&

.RIW Watches/Warnings/Advisories...
None.
&&

$$

SHORT TERM...Lipson
LONG TERM...Skrbac
AVIATION...Skrbac
FIRE WEATHER...Lipson



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