Scientific Forecaster Discussion

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Area forecast discussion 
National Weather Service Pocatello Idaho
153 PM MDT Thursday Apr 24 2014

Short term...tonight through Saturday night.

Low pressure system moving onto the coast will produce wet weather
across the region through Saturday. Showers will mainly affect the
mountains and upper snake Highlands this evening. Overnight a large
batch of precipitation will arrive and overspread most of the
region. This initial batch of precipitation will last until around
middle afternoon. Snow levels will sit around 7000 feet and higher
elevations in the central mountains could see an additional 4 or 5
inches of snow by midday Friday. A second round of precipitation
will arrive late afternoon and persist through the evening. This
batch of precipitation will mainly affect the snake plain and
eastern Highlands. Expect a short break around midnight on Friday
night before the final round of precipitation arrives into southeast
Idaho before daybreak on Saturday morning. This round of
precipitation is associated with the cold front. This precipitation
will linger across the eastern Highlands through Saturday afternoon.
Snow levels will fall to 5500-6000 feet behind the front and some
portions of southeast Idaho...mainly above 6000 feet...cold see 1 to
3 inches of snow Saturday morning. Most of the precipitation
associated with this low pressure system will come to an end
Saturday night. Quantitative precipitation forecast totals of 0.25 to 0.75 inch is likely with this
system across much of the area. The heaviest amounts are in the
mountains and Highlands...still some communities in the snake plain
could see half an inch from this system.


Long term...Sunday through Thursday. We will see showers on Sunday
as moisture is still pushing through the backside of splitting
system...that is now off to our north and east. A slow drying trend
is on tap for Monday as high pressure begins to build across the
west. We will not be totally dry with some shower activity possible
mainly across the central and eastern mountains. Beyond Monday...the
forecast will be pretty slow to move as a blocking pattern sets up
over the entire country. The main issues right now are where exactly
the ridge out west sets up...with storms on either side of it
anchoring the pattern in place for a few days. The GFS has been
rather persistent with centering it over the state. The European model (ecmwf) has
actually been shifting the ridge closer to the West Coast and Idaho
stuck on the back side of a big storm out over the plains. This
would present an occasional wave of showers dropping south or
southwest across US. The GFS would be mostly dry with a very small
chance of any development along The Divide or Wyoming border.
Ensemble data shows more support for a stronger ridge vs something
similar to the European model (ecmwf). For now...we kept it dry with a warming trend.
Confidence is still not too high on that scenario however. Keyes


Aviation...occasional waves of rain and snow will plague eastern
Idaho through tomorrow...and in reality all the way through Sunday.
Gusty winds will be an issue into the evening hours before tapering
off. Most areas tonight will see an overall break from any
precipitation but a few showers may creep we have vcsh in
the tafs. More widespread rain and higher elevation snow will return
after 8z. VFR weather should be the norm...but we could see dips
into MVFR at times. Keyes


Pih watches/warnings/advisories...