Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Boise Idaho
241 am MST sun Dec 21 2014
Short term...today through Monday...the warm front is finally
showing signs of punching northward as the models have promised.
Bogus Basin is above freezing and the web cam indicates rain. Kmyl
is still snowing...but should change to rain shortly. The west-southwest will
be allowed to expire at 3 am with the morning forecast package.
Light to moderate rain is still falling over most of the region...
and we expect it to continue for much of today as a warm moist
flow remains entrenched aloft. Latest hrrr model indicates a break
this morning in the lower Treasure valley and western portions of
the upper Treasure valley...including Boise. But then precipitation
spreads back into these areas this afternoon. This will have a
strong impact on temperatures today. We have lowered the forecast
for these areas due to high-resolution model data indicating
less warming than previously expected today. As we move into
tonight...snow levels move back down and moisture will finally
begin to decrease. The chance of precipitation decreases sharply Monday
and temperatures will cool further. Winds will be strong today in southeast
Oregon...the southwest Highlands of Idaho...and the higher terrain
of southern Twin Falls County. The Wind Advisory is still on track to go
into effect at 8 am MST and run until 5 PM MST.
Long term...Monday night through Saturday...conditions are
expected to continue to dry out Monday night and Tuesday as a
ridge off of the California coast amplifies. This will keep
temperatures above normal. Models are in good agreement of the
ridge starting to flatten out on Wednesday ahead of a trough
moving in from coastal British Columbia. The latest GFS and European model (ecmwf)
runs have begun to agree on timing of this trough and associated
cold front. Precipitation chances will spread from northwest to southeast late Wednesday
night with snow levels around 5000 feet dropping to 2000 feet by
early Christmas morning. However...this system will likely move
out of the area quite quickly so conditions should dry out once
again Christmas afternoon/evening. The associated cold front will
bring temperatures back to near normal for the rest of the period.
A cooler northwest flow will set in for Friday and beyond.
Aviation...VFR/MVFR conditions with rain and high elevation snow
will continue through the period. Isolated IFR conditions and
mountain obscuration still exist in the west central mountains...
but as those areas turn to rain this morning...expecting some
improvement in vis/ceiling. Surface winds will be generally northwest
with stronger gusts in the Magic Valley and southward...and
southeast Oregon. Winds aloft near 10k feet...northwest at 50-70 kts.
Idaho...Wind Advisory from 8 am this morning to 5 PM MST this afternoon
Winter Weather Advisory until 3 am MST early this morning idz011.
Or...Wind Advisory from 8 am MST /7 am PST/ this morning to 5 PM MST
/4 PM PST/ this afternoon orz061-063.
Short term...snow pellets