Area Forecast Discussion
Issued by NWS Pocatello, ID

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520
FXUS65 KPIH 170904
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
304 AM MDT Mon Apr 17 2017

.SHORT TERM...Today through Wednesday. Cold front as of 230am was
pushing through the central mountains and Magic Valley. This
boundary continues to work east and out of the state by lunchtime.
We are seeing showers forming as expected especially just behind
the front. In the mountains, we are seeing some decent
precipitation amounts. In the lower elevations, it is very dry
although we are seeing that trending the other way slowly. This
causing some concern as we might be a bit overdone on rain and
snow amounts. We will be watching to see if that indeed is the
case. Snow levels drop to around 6500ft in the central mountains
and range up to around 8000-8500ft in the southeast corner today.
The other story will be gusty winds developing, with 15-30mph and
higher gusts for many locations. The strongest winds should be
across the Upper Plain (especially along/west of I-15 back toward
the INL and Arco Desert regions). While winds are not terribly
strong, the last wind event did kick up blowing dust and we are
thinking that is certainly possible today. Therefore, we will
issue a Wind Advisory in those areas for this afternoon through
sunset. By this evening, we`ll see a let up in showers but that
will only be for a few hours. The leading edge of the next round
of showers will be developing across the southern highlands, Magic
Valley and Sawtooths/Wood River Valley area. Showers will spread
over eastern Idaho overnight and Tuesday. Right now, the best
chances are still south of a Driggs to Burley line although in the
afternoon...showers are forecast for just about anywhere. We are
looking for isolated thunderstorms as well. A rapid decrease in
activity happens west to east tomorrow night. HOWEVER, we are
seeing the potential for a convergence band to develop north of
the INL and Idaho Falls. Snow levels actually rise overnight and
peak tomorrow at ~7500ft in the central mountains and ~9000ft
around Bear Lake. Wednesday will be drier in the west will still
some lingering showers across the eastern highlands. Temperatures
don`t drop a whole lot early on in the week, staying with a couple
degrees of average above or below. Keyes

.LONG TERM...Wednesday night through Sunday.
Models are in better agreement this morning with respect to the
upper level trough coming in Thursday and Friday. Rather than dig
energy to the Four Corners area, the south end tracks between
central Colorado and the WY/CO border. Precipitation is more
widespread over Southeastern Idaho, but with snow limited to 1 to 3
inches above 7000 feet elevation. Snow levels in the Central
Mountains dip to near 6000 feet Thursday morning, but with
accumulations below 7000 feet probably less than one inch. Clearing
trend expected Friday and Saturday with a high pressure ridge moving
across the area. Now model differences are greater on Sunday, GFS
took a sharp turn towards a stronger disturbance coming through,
which could be over done. The upper level flow pattern still looks
less amplified. Added a low chance of precipitation to the forecast
for now. RS

&&

.AVIATION...Upper low tracking from Oregon to Montana today,
surface pressure falling near the Divide this morning with trailing
front likely across the Upper snake Plain. MVFR ceilings at KSUN
this morning, clearing 18-19Z. At KDIJ, MVFR with showers 15-21Z. At
KPIH, KIDA, and KBYI showers more vicinity in nature this morning,
with winds the bigger story. Expecting SW winds increasing to 15 to
25 mph with gusts up to 40 mph early this morning and continuing
through the day. Strongest winds focused over the Arco Desert where a
wind advisory has been issued. Very short break with new disturbance
moving in Tuesday morning. RS

&&

.HYDROLOGY...Next round of precipitation moves into East Idaho
through Tuesday night with brief reprieve most areas Wednesday.
Snow levels drop briefly into Monday night but recover Tuesday
and Wednesday. Have kept flood advisory going for Bear Lake region
for expectation that minor mainly field flooding continues. Bear
River stage low enough to expect river is within banks most of
stretch, but creeks and streams likely still running high.
Portneuf River remains in minor flood stage with no expected
improvement. Snake River at Blackfoot has briefly approached low
end minor flooding, but expected to remain below there through
early week. Will be interesting to see how active pattern this
week influences river levels later in the week. DMH

&&

.PIH WATCHES/WARNINGS/ADVISORIES...
Wind Advisory from noon today to 8 PM MDT this evening for
IDZ019-020.

&&

$$



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