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Area forecast discussion 
National Weather Service Boise Idaho
956 am MST Sat Nov 28 2015

Discussion...much of the Treasure and Magic Valleys as well as
valleys in southeast Oregon are inverted. Fog and low stratus are expected
to remain in many of these areas through the day...with possibly
a brief break in the late afternoon. Temperatures expected to
remain well below normal...with low stratus areas experiencing a
low diurnal temperature swing. Updated the forecast to slightly
adjust temperatures and add in cloud cover where the stratus has
become more widespread.


Aviation...IFR in fog and low stratus over the snake plan...Weiser
basin and areas of northern Harney County this morning. Little
change in conditions today with some further expansion of IFR in
fog/stratus into the western Magic Valley /to include ktwf and
kjer/. Some erosion to the fog/stratus is possible in the Treasure
valley but it would be patchy and short lived at best. Tops of
stratus at kboi are about 1500 feet above ground level. Surface winds generally 10
kts or less. Easterly winds aloft 15-25 kts at 10k feet mean sea level.


Previous discussion...
short through Sunday...a cold stable stagnant
pattern will continue this weekend. A large upper low to our south
will slowly shift east-NE while high pressure aloft builds in from
the west. A very cold air mass has settled into the region. Once
again...temperatures this morning are in the single digits and
teens...with sub-zero readings in much of Harney County and the
Camas Prairie. The stable pattern has also allowed an inversion to
develop and will remain in place for several days. Widespread
stratus/patchy fog encompasses the Treasure valley and upper
Weiser basin. Visibilities will likely improve this
afternoon...but the patchy fog will return this evening and continue
through Sunday morning. There will also be some erosion of the low
stratus this afternoon...but will probably re-develop and expand
throughout the valleys this evening...then improve again Sunday
afternoon. Temperatures will be very cold again tonight...with
record/near record lows expected at a few locations. Winds will be

Long term...Sunday night through Friday...cutoff upper level low
will continue to move east Sunday night with an upper level ridge
over the forecast area Monday through Wednesday. This weather
pattern will keep conditions dry with temperatures remaining below
normal. Models in better agreement with the pattern from
Wednesday through the end of the week but there still are timing
differences on when precipitation will move into the forecast
area. Axis of the ridge will begin to move east as a long wave
trough develops over the eastern Pacific. Models have slowed
down the timing of precipitation so Wednesday looks to be dry but
if timing of precipitation changes could see precipitation move
into the forecast are Wednesday afternoon. As the axis of the
trough moves inland on Friday will see increasing chances of
precipitation over the region Wednesday night through Friday.
Models hinting that this trough could split as it moves over the
area and keep most of the precipitation to the north and south of
the forecast area. With uncertainty on how much this trough will
split will trend probability of precipitation towards climatology and adjust the forecast
as confidence in the models increases. Temperatures will slowly
warm through the end of the week but will be a few degrees below
normal by Friday.


Boi watches/warnings/advisories...




previous short
previous long term....ja

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