Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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267
FXUS65 KBOU 082234
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
334 PM MST Thu Dec 8 2016

.SHORT TERM...(This afternoon through Friday)
Issued at 330 AM MST Thu Dec 8 2016

Moderately strong northwesterly flow aloft will continue over the
forecast area tonight and Friday. The synoptic scale energy is
benign tonight and Friday. Normal diurnal wind patterns are
progged for the plains and drainage winds are progged overnight.
foothills tonight and Friday. The higher mountains can expected
west and northwesterlies strong enough for some blowing snow.
Models have moisture increasing and getting pretty deep for the
mountains and current satellite pictures concur with this. The QPF
fields show fairly decent precipitation/snowfall amounts in the
mountains tonight and Friday. Snow advisory criteria looks fine in
the mountains with the moisture and orographic enhancement. Will
leave highlights as is. For temperatures, Friday`s highs will be 8
to 13 C warmer than today`s highs.

.LONG TERM...(Friday night through Wednesday)
Issued at 255 AM MST Thu Dec 8 2016

Moist flow from the NW will continue into the extended generating
more orographic snow in the Mountains. Snow fall will wind down a
bit Friday night into Saturday with some light snow still expected
with continued orographic influence. The plains will remain dry on
Saturday with a lee side low near the base of the Foothills keeping
winds downsloping onto the plains warming temperatures into the 50s
for Saturday. The strong WNW flow will bring increased wind gusts to
the mountains but with little shear near mountain top and
subsequent stable layer do not expect the winds to make it down
the Foothills. Winds of 35 to 40 in the mountain valleys to speeds
up to 60 near mountain top will be possible Through the day
Saturday creating blowing and drifting snow and potential
hazardous driving conditions for weekend travelers.

Saturday night into Sunday models have the upper jet dropping south
into the Northern mountains combining with a conveyer belt of
Pacific moisture to increase snowfall over the mountains Saturday
night through Sunday. Looking at 700 mb...temperature values are
higher then with the previous storm with the influence of WAA from
westerly flow aloft. Therefore expect a lower snow to liquid ratio
with this storm and heavier more wet snow. Current QPF models 12
hour accumulations from 0.30 to 0.60 with the higher amounts over
west facing slopes. This could equate to snowfall amounts of 4.5 to
9 inches and combined with continued wind gusts up to 50 mph an
advisory may be needed. A cold front will move into the northern
plains from Wyoming bringing slightly cooler air. The increased NE
flow on the plains behind the front will have to compete with the
strengthening surface low close to the foothills in achieving
desired upslope. Will keep a slight chance on the plains Sunday
morning but confidence is low for much precipitation on the plains.
Temperatures will only be slightly cooler then Saturday with highs
in the 40s.

For next week the upper level pattern will continue to be strong
from the WNW. Models are coming into better concensus with an arctic
push of cold air from the north bringing temperatures on the plains
back to the teens and 20s and possibly below zero overnight by mid
week. The only model that keeps it further east is the EC so will do
an average of temps for that period with more emphasis to the cooler
side. Snow will continue in the mountains with the only difference
through the week being intensity. This will change as the days go on
seeing where models put jet placement and the best lift.
Temperatures for next week will hover around normal with the drop by
mid week then back above freezing by Thursday.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 335 AM MST Thu Dec 8 2016

Drainage winds should kick in by 02Z this evening and continue
overnight. Friday`s winds should also adhere to normal diurnal
patters with a weak low level pressure gradient in place. There
should be no ceiling issues.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory from 7 PM this evening to 5 PM MST
Friday for COZ031-033-034.

&&

$$

SHORT TERM...RJK
LONG TERM...Bowen
AVIATION...RJK



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