Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Boise Idaho
839 PM MST sun Nov 29 2015
Discussion...today was generally a little colder and cloudier
than Saturday. Higher elevations cooled about 5 degrees from
Saturday while valleys changed little from Saturday. No significant
weather changes are expected through early Thursday...although a weak
Pacific storm will increase clouds and bring a chance of snow
showers Wednesday to Baker County and the west central Idaho
mountains. Storm Thursday night may be strong enough to break
the inversion and bring more extensive precipitation...as snow. Current
forecast looks reasonable with only slight day to day changes
from persistence until faster warming with increasing east or southeast
winds Wed/Thu. No updates.
Aviation...low MVFR in low stratus and fog over the Snake River
basin...Weiser basin...Baker County and areas of northern Harney
County. Already seeing LIFR conditions at kjer at 03z/Mon...and
expect IFR and local LIFR conditions to return to these valleys
/and also the Long Valley/ overnight. Like yesterday...expecting
pockets of clearing tomorrow afternoon. The rest of the forecast
area is mostly clear. Surface winds...generally 10 kts or less.
Winds aloft up through 10k feet mean sea level...north-northeast 10-20 kts.
short term...tonight through Tuesday...widespread low stratus and
patchy fog expected to continue through the period in valleys...
especially from the magic through the lower Treasure. With no
pattern change expected through Tuesday...brief breaks in
stratus/fog may occur in the late afternoons...but fill back in
soon after sunset. Temperatures in these areas will remain well
below normal with little diurnal swing. Isolated flurries from
the stratus but no major impacts are expected. Otherwise cold and
dry conditions will prevail across higher elevations of southeast Oregon
and SW Idaho through Tuesday.
Long term...Tuesday night through Sunday...clouds increase across
southeast Oregon Tuesday night as upper ridge axis shifts east of the
area. A weak short wave trough embedded in the flow will bring southeast
Oregon and west-central Idaho mountains a chance of light snow showers on
Wednesday while an increase in easterly winds will gradually
scour out any remaining low stratus by Wednesday afternoon.
However...the inversion remains in place through Wednesday with
valley temperatures well below normal. The European model (ecmwf) and GFS agree on
a second short wave trough tracking across the region late
Thu/Fri...though with differences in the amplitude and timing.
Given the mean ridge over the interior northwest the European model (ecmwf) solution...
which splits the trough as it moves inland...is favored at this
time. An upper ridge axis transitions across the region Sat/sun.
Moisture along the periphery of the ridge will keep a slight
chance of snow showers over the east-central Oregon and west-central
mountains each day.
Air stagnation...inversion will remain in place well into the
upcoming week. Top of the inversion is around 8k feet mean sea level off the
latest kboi weather balloon. Surface based mixed layer will be at
or below 1500 feet above ground level through Wednesday. Winds in the surface
mixed layer will remain light /less than 10 miles per hour/ through
Tuesday...likely increasing out of the east Tuesday night into
previous short term...ep
previous long term....dg