Frost Advisory 1, NWS Pocatello, ID

Area Forecast Discussion
National Weather Service Pocatello ID
317 AM MDT Mon Jun 11 2018

.SHORT TERM...Today through Wednesday. The big story early on this
week is continued cold temperatures and gusty winds. That said, we
are dealing with some showers moving across the central mountains
toward Monida Pass and Island Park. The trend through the rest of
today will be for this to shift northeast. By later in the
afternoon, showers will remain across Lemhi County and across the
Island Park area, maybe as far south as Teton Pass. There will be
light snowfall possible as low as 5500-6500ft farther north, but
don't expect much accumulation/impact even in the backcountry.
Winds today will be gusty again, 20-30mph with some higher gusts.
The strongest winds will be across the Snake Plain (especially
Arco Desert east to I-15), where 25-35mph winds with higher gusts
are forecast. We will send up the Wind Advisory for the Upper
Plain, and a Lake Wind Advisory for American Falls Reservoir.
We will quickly lose the wind this evening, and any clouds/showers
left over for this afternoon. With dry air in place, this will
allow temperatures to plummet lower than many places are this
morning. Many areas will see a frost if not a freeze. We should
stay warm and just breezy enough to stave off frost conditions
along for more populated areas of the Snake Plain and into the
southern highlands. We will issue a Frost Advisory for the Snake
Plain overnight and Tuesday morning. Welcome to June everyone.

The rest of Tuesday and most of Wednesday looks dry with warmer
weather returning. Highs each day jump about 10 degrees across the
board.The forecast gets a bit questionable Wednesday evening. As
the next storm enters the Pacific Northwest and British Columbia,
there should be some moisture streaming back across the state as
southwest flow strengthens. Will be enough for actual showers or
storms? That remains a BIG if at this point, but it will at least
bring some increase in clouds. Because of the big if, we did
include a very small chance (around 10 percent) across the
mountains.  Keyes

.LONG TERM...Thursday through next Monday. It appears we are
headed for another period of stormy and cooler weather. The
questions remain on how stormy and how cool. The GFS and ECMWF
continue to each day come up with a different idea. The latest is
to take the low entering the Pacific Northwest and eventually
develop a slow moving, closed low over the northern Rockies and
Great Basin. We did start the process of increasing the chance of
showers and storms a bit more along with trending temperatures
down some. We didn't go too far in any one direction and went with
the blended forecast approach. Keyes

&&

.AVIATION...Another windy day in the Upper Snake Plain, southwest
wind 25 to 30 kts expected at KIDA, slightly less at KPIH until
sunset. Otherwise, VFR today and Tuesday. RS

&&

.FIRE WEATHER...The second of two disturbances will
cross northern Idaho today. Isolated rain showers will occur this
morning mainly north of Challis and Monida Pass. By early afternoon,
most of the moisture and any showers will be moving quickly into
Montana. Windy conditions are expected again today in the Upper
Snake Plain, and rather "breezy" conditions in the Lower Snake
Plain. A Wind Advisory is in effect for the Arco Desert area 1000 to
1900 hours. Tuesday will be sunny and dry, with temperatures
continuing to rebound off the cold temperatures of Sunday. Most
valley areas will be solidly in the 70s, and a few 80F values
observed in the Raft River area. Afternoon humidity around Craters
of the Moon and Challis are expected to dip into the lower and
middle teens. Models still favor tracking our next disturbance
across Washington and the north half of Idaho late Wednesday night
and Thursday. A cold front should cross the Salmon-Challis NF
Wednesday night with a chance of showers, while the Snake Plain
should see a slight chance of showers and thunderstorms Thursday,
along with another windy day from Shoshone to Dubois. Friday and
Saturday will be 10 to 15 degrees cooler with scattered showers
under a much broader low pressure disturbance. RS

&&

.HYDROLOGY...Flows across East Idaho are in a downward trend. As of
today, several gages have dropped below advisory criteria which
allowed us to cancel those headlines: Big Lost River at Howell
Ranch, Snake River near Idaho Falls and Snake River at Blackfoot.
The Advisories continue for the Big Wood at Hailey and Antelope
Creek near Darlington, and the Warnings continue for the Snake
near Menan and the Big Lost below Mackay Reservoir. The strong
cold front arriving tonight will usher in significantly cooler
temperatures across the region for Sunday into Monday, warming
into mid week. These cold temps are expected to significantly
mitigate the snowmelt, allowing further drops on waterways. This
may have a cascading affect on reservoir releases into midweek as
well. DMH

&&

.PIH WATCHES/WARNINGS/ADVISORIES...
Frost Advisory from midnight tonight to 9 AM MDT Tuesday for
IDZ017-020-021.

Lake Wind Advisory from 10 AM this morning to 8 PM MDT this
evening for IDZ021.

Wind Advisory from 10 AM this morning to 8 PM MDT this evening
for IDZ020.

&&