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fxus65 kpih 240910 

Area forecast discussion
National Weather Service Pocatello Idaho
310 am MDT Fri Mar 24 2017

Short through Sunday...a high pressure ridge in
place this morning will gradually give way to an approaching low
pressure trough and weak frontal boundary this afternoon and
evening. Snow in the Central Mountain peaks are expected to be
impacted first, following by rain in the valleys and snow above
6500 ft east and southeastward. Snow amounts will vary between 4
to 8 inches at mountain peaks with 3 to 5 inches possible at
mountain passes from this afternoon through Saturday. Heaviest
snow is expected this evening. Several areas through southeast
Idaho are likely to see a mixture of rain and snow today as the
snow levels will increase during the daytime and drop to near
6000 ft overnight. A fairly moist Friday night through Saturday
morning in several locations is anticipated where 1/10 to 1/4
inch of rainfall over a 6 to 12 hour period are forecast. Daytime
Saturday will start to dry out for the snake plain and portions
of the central mountains as a split-flow pattern develops over
our region. Moisture will cling to the north, including the
Continental Divide and upper portions of the Salmon-Challis nf,
along with rain and snow persisting to the south along the
Utah/Idaho border. By the overnight hours, we should see the
moisture leaving our area to the east and high pressure builds
in. Temperatures tomorrow compared to today will only drop 5 to 8
degrees or so in the wake of the passing boundary. For some,
temperatures will not change at all. Additionally today, wind
gusts in the central mountains and southern Highlands are forecast
in the 25 to 35 mph range with gusts in the snake plain reaching
25 mph. Therefore, blowing snow is possible this evening where new
snow falls including Banner Summit and Galena Summit. Np/receiver station


Long term...Monday through Thursday. GFS and European model (ecmwf) are close
in timing and position of 500mb heights as the new trough moves
inland and splits, the southern end closing off a circulation close
to The Four Corners area by Tuesday morning. The main difference is
in handling of the moisture, the European model (ecmwf) has deeper moisture further
north in Wyoming and along the eastern Highlands in Idaho. Blending
models is a good compromise for the moment. Estimate snow amounts
Monday morning to Tuesday morning around 1 to 4 inches in the
mountains with snow levels near 6000 feet and not dropping much
until Tuesday afternoon. By that time, just a few showers linger
along the Wyoming line. A short break in activity follows until the
next surge of moisture advances into the central mountains Wednesday
morning and reaches the upper snake Highlands by Wednesday
afternoon. There is much more uncertainty with this disturbance as
the GFS aggressively digs a new closed circulation down into Arizona
by Friday morning. Continued to use a model blend as the differences
are pretty strong. Receiver station


Aviation...the NAM has been pretty consistent on timing of the
disturbance crossing southeast Idaho this afternoon and tonight.
Surface lows in Montana and another crossing Nevada/UT, the southerly
winds increase in the snake plain near 19z today at 10-15kts, wind
shift at kbyi 25/01-02z and kpih 25/03-04z. NAM timing of
precipitation is preferred with MVFR ceilings at ksun by 22z and kbyi
near 25/03z. Kpih and kida follow about 25/06z and continue into
early Saturday morning. Receiver station


Hydrology...the Portneuf River at Pocatello has been steady
with some recent doubts that it will reach moderate flood status.
The current forecast teeters the moderate/minor flood stage line
this weekend. It remains a Flood Warning. The Bear river at
border is in minor flood stage with forecasts to decrease through
early next week. A Flood Warning remains in effect. Otherwise,
all other flood advisories and areal flood watches remain intact
where current flooding exist or where trouble spots have been
identified by emergency management. Np/receiver station


Pih watches/warnings/advisories...
Flood Watch until noon MDT today for idz017>019-022>025-031-032.

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