Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 042228

Area Forecast Discussion
National Weather Service Denver/Boulder CO
328 PM MST Sun Dec 4 2016

.SHORT TERM...(This evening through Monday)
Issued at 328 PM MST Sun Dec 4 2016

Westerly flow aloft will be increasing over northern Colorado
tonight as an upper level jet moves in from the Pacific Northwest.
Moisture associated with the developing flow pattern will also be
on the increase over the mountains by 06z and continuing through
Monday. The core of the upper level jet will be staying over
Wyoming with ridgetop flow in Colorado peaking out at around 70
knots. Model cross sections indicate that the fastest flow will
remain over the ridges, without much of a lee-slope mountain wave
developing. Quasi-geostrophic diagnostics also show a lack of
strong subsident forcing overnight, which may be why a strong wave
does not develop. At any rate, the strongest winds are expected to
remain above 10,000 to 11,000 feet, with lesser impacts down in
valleys and population centers. No highlights will be issued.
Light snow will also be developing in the mountains overnight, but
only light amounts, up to about 4 inches, are expected through
tomorrow afternoon.

On the plains, one last mild day will be in store, but by mid-
afternoon cooler air is expected to begin moving in from the
north. High temperatures in the mid 40s to lower 50s will be
possible, primarily by the lunch hour. Dry conditions will prevail
through later Monday night. Afternoon gusts on the plains will be
in the 25 to 35 mph range.

.LONG TERM...(Monday night through Sunday)
Issued at 328 PM MST Sun Dec 4 2016

A dramatic change in the wx ptrn will occur Tue into Wed as an upper
level trough moves along with a couple of cdfnts.  Mtns will see
some snow Mon night into early Tue however best chc of heavier snow
will be Tue aftn and night when best QG ascent moves across in
association with deeper moisture.

Across nern CO first shot of colder air will move in Mon night into
early Tues with a brief shot of upslope flow Mon night.  Overall
with lack of QG ascent Mon night thru Tue morning and a dry lyr in
the lower levels will only see a chac of light snow mainly in and
nr the foothills. Highs on Tue will be in the mid 20s to around
30 across the plains.

By late aftn into Tues night upslope flow will gradually increase as
a sfc low forms over srn CO and a secondary shot of colder air moves
into nern CO.  Meanwhile QG ascent will increase across the area
which will lead to a gradually increase in snow in and nr the
foothills and across the rest of the plains Tue night.  Based on
current data and timing of upper level trough snow may linger into
Wed morning as well before gradually ending in the aftn.  As for
amounts HI RES WRF and SREF Plume data indicate advisory amounts fm
the foothills across the plains with the potential for heavier
amounts around the Denver area.  Confidence is not high enough to
issue a watch at this point since the heaviest snow at lower
elevations will be from Tues night into Wed morning.  Meanwhile
highs on Wed will only be in the teens across the plains.

For Wed night into Thu drier air will spread across the area in nw
flow aloft.  Outside of a chc of light snow in the mtns Wed night it
will be dry thru Thursday.  Morning lows on Thu will likely be below
zero across much of the area.  As for highs on Thu readings will
only be in the upper teens to lower 20s across the nern Co.

For Fri and Sat the flow aloft will become more wly with moisture
affecting the mtns both days with a good chc of orographic snow.
Across nern CO it will be dry with moderating temps on Fri as
downslope flow develops with readings mainly in the 30s.  On Sat a
wk fnt may move across nern CO which would keep readings in the 30s.

On Sun a weak upper level trough is fcst to move across bringing
another chc of snow to the mtns.  Across nern CO will not mention
any pcpn and will keep highs in the 30s.


.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 328 PM MST Sun Dec 4 2016

Cloud heights are expected to remain high overnight as moisture
aloft increases over the state. Winds will be out of the west or
southwest, especially over the western portions of the Denver area
where gusty winds are expected at times overnight. On Monday,
cloud cover will be increasing through the day, but ceilings are
expected to remain above 6000 ft AGL through the late afternoon.
Winds are expected to increase in the afternoon and shift to north
or northwesterly as an initial surge of cold air begins moving
into northeast Colorado. No aviation impacts, other than changing
wind directions are expected through tonight and Monday afternoon.




SHORT TERM...Dankers
AVIATION...Dankers is the U.S. government's official web portal to all federal, state and local government web resources and services.