Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 031023
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
323 AM MST Sat Dec 3 2016

.SHORT TERM...(Today and tonight)
Issued at 110 AM MST Sat Dec 3 2016

Water vapor imagery showing upper level trof moving across central
Colorado at the present time with some drying noted over the
Front Range. Expect an uptick on winds in the mountains and east
slopes as this subsidence moves over us. Cross sections also
indicate an increase in wind speeds as cross barrier flow
increases to 30-40kt this morning before decrease some later this
afternoon and tonight. Given this modest west to northwest flow
and lingering moisture below 600mb...expect areas of light snow
will continue over higher mountains, most likely by late am
through the afternoon hours. Any accumulation will be around an
inch or less due to shallow moisture and downward synoptic
forcing. Main change to forecast was to increase pops in the
mountains today and increase wind gusts a little this morning.

As for lower elevations, there is some lingering low level
moisture over Lincoln county and over the far ne corner of
Colorado. As the trof sweeps through by daybreak, these lower
clouds will also move out of the area. Temperatures will be
somewhat warmer today with readings back into the lower 40s with
much more sunshine expected. There will be some wave cloudiness
but a thick wave is not anticipated.

.LONG TERM...(Sunday through Friday)
Issued at 110 AM MST Sat Dec 3 2016

Sunday and Sunday night...a dry but increase west/northwesterly
flow aloft will develop over CO during the day, with the surface
lee trough along near the foothills. As a result, this will be the
warmest day of the period, with gusty westerly winds developing in
the mountains and higher foothills Sunday night into Monday. Mid
and upper level moisture will increase over the northern mountains
Sunday night, as an upper level disturbance moving across the
northern Rockies moves into central Montana by 12z Monday. Chance
of snow will develop in the mountains west of the Continental
Divide after 06z ahead of this trough. Monday and Monday night, a
strong zonal flow aloft will be over northern CO as the upper
level jetstream stretches from the Pacific Northwest and across
the central Rockies. Light snow will continue in the mountains on
Monday mainly west of the Continental Divide. Dry and continued
mild across the northeast Plains with the surface low moving south
into southeast Colorado. As a result, surface winds will be
northwesterly over the urban corridor and northeast plains. A
strong cold will push through the northeast plains Monday evening
with gusty northerly winds across the area. A strong westerly
flow aloft with increasing Pacific moisture wl develop in the high
country. The present of the jetstream aloft may help to enhance
snowfall in the mountains Monday night into Tuesday. The chance of
snow will spread across the northeast plains Tuesday and Tuesday
night. Anticyclonic upslope along the Front Range and Palmer
Divide should allow for best chc of accumulating snowfall in the
foothills and east facing mountain slopes, with the mdls
generating around 6 inches there, with lesser amounts across the
Northeast Plains in the 1-4 inch range. Best estimate in the
mountains may be in the 4-10 inch range for Monday through Tuesday
night. Some winter highlights will likely be needed at that time.
At this point leaning more towards advisories vs warnings if
these solutions pan out. Much colder Tuesday and Wednesday. 500 mb
temperatures around -30c for 12z Tuesday and -36c ovr northern CO
at 12z Wed. A strong northwesterly flow aloft will be over
Colorado Wednesday night with the main upper trough axis shifting
northeast near Hudson Bay by that time. Drier with the chance of
snow dropping off Wednesday into Wednesday night. A ridge of high
pressure will build into Colorado Thursday into Friday with the
cold Arctic airmass moving into the Midwest. This will allow for
temperatures to moderate back into lower 40s by Friday.

&&

.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 110 AM MST Sat Dec 3 2016

Surface winds shifting a bit more sw-w early this am as upper
trof now moving over area with large scale subsidence and stronger
winds aloft. Behind this trof there is some upper level moisture
which will move back in around midday. Otherwise VFR through
period with overall wind speeds remaining under 12kt at local
terminals. Gustier winds will remain over mountains and east
slopes with gusts up to 35kt over wind prone areas.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

SHORT TERM...Entrekin
LONG TERM...Cooper
AVIATION...Entrekin



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