Area Forecast Discussion
Issued by NWS Boise, ID

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FXUS65 KBOI 222049

Area Forecast Discussion
National Weather Service Boise ID
249 PM MDT Thu Mar 22 2018

.SHORT TERM...Warn-frontal rain was still falling in the Boise
Mountains and west-central Idaho early this afternoon.  This rain
will shift east and out of our CWA late today.  A Pacific cold
front in eastern Oregon this afteroon will reach the OR/ID
border about 5 PM PDT (6 PM MDT), then continue across western
Idaho between 6 PM and 11 PM MDT.  The cold-front will have
showers and isolated thunderstorms with gusty winds, locally heavy
rain, and small hail or graupel.  Precipitation should last about
one hour at any given location.  Drying and colder tonight behind
the front.  Slight chance of rain and snow showers again Friday in
the mountains of eastern Oregon and west central Idaho.  The main
upper trough off the coast will send a short wave trough inland
across Oregon late Friday night, and western Idaho Saturday,
bringing a chance of rain and snow showers.  Snow level will lower
from 7000-8000 feet MSL ahead of the front today, to 3000-4500 feet
MSL Friday, and 3000-4000 feet MSL Saturday, i.e., down to valley
floors.  Snow showers will bring 1-3 inches accumulation to higher
terrain late Friday night and Saturday, but valleys will have little
if any accumulation.

.LONG TERM...Saturday night through Tuesday. Upper level trough off
the West Coast will move inland on Sunday and track across the Great
Basin on Sunday. Models still showing some differences in the track
of the low, which will dictate where precipitation sets up. Snow
showers are possible across the region on Sunday as snow levels will
be to the valley floors. Not expecting accumulations below 4000 feet
with light accumulations above. Moist and cool northwest flow will
keep a chance of snow showers over the mountains through Tuesday
with continued below normal temperatures.

Tuesday evening through Friday morning. Sunny skies and warmer
temperatures in store as northwest flow and ridging are the
dominating weather factors. Models are in agreement with this
pattern to persist at least through Friday with periods of
increasing moisture and cloudiness across the northeast section
of the CWA; however, no precipitation is anticipated. Gradual
warming is expected to increase high temperatures to 4 to 6
degrees above normal while lows hover near normal.


.AVIATION...Scattered showers with low VFR to MVFR conditions and
mountain obscuration. A cold front late this afternoon will produce
showers with gusty winds and the possibility of thunder and graupel.
Front will reach KBNO around 20-22z, KBOI 00-02z, KTWF 04-06z.
Surface winds SW-SE 15-25kt ahead of the cold front, gusty erratic
winds up to 45kt possible along front, becoming light overnight.
Winds aloft at 10kft MSL: SW 25-35kt.





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