Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 022209
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
309 PM MST Fri Dec 2 2016

.SHORT TERM...(This evening through Saturday)
Issued at 309 PM MST Fri Dec 2 2016

The upper level low will move SE over AZ and NM through the
evening pulling gulf moisture into Colorado. This moisture is
combining with some ESE upslope flow to bring continue light snow
showers to the Foothills and areas around DIA and west. Northern
portions of Metro Denver will see some light snow with areas
further south not due to downsloping off the Palmer. Closer to
the lower Foothills such as Boulder and north into Eastern Larimer
could see some light snow into the evening. Accumulations in the
Foothills could be as high as 2 inches with a trace expected in
Denver and DIA. Accumulations will mainly be on grassy areas but
some roads at higher elevations could get slick so caution is
advised.

For tonight an upper level trough will drop Southwest into
Colorado bringing increasing subsidence behind it. With the NW
flow becoming deeper and lingering moisture in the mountains will
keep some pops through the overnight hours with a slight chance of
light snow due to orographic influence. At lower elevations snow
will taper off by the early hours on Saturday leaving some clouds
in the morning before partly cloudy skies in the afternoon.
Temperatures for today will stay in the lower 30s with teens
overnight. On Saturday highs will rebound back into the 40s for
the start of a dry weekend.

.LONG TERM...(Saturday night through Friday)
Issued at 309 PM MST Fri Dec 2 2016

Warm and dry conditions are still expected through the medium
range portion of the forecast as weak riding aloft remains over
the state, ahead of the developing upper trough that will affect
Colorado weather through the bulk of next week. Temperatures on
Sunday and Monday will be at or slightly warmer than normal.

Changes will begin affecting the north central mountains Monday
afternoon and evening as the first moisture ahead of the
approaching trough begins producing snow in the mountains. The
nose of an approaching upper level jet is also expected to help
with vertical lift associated with the approaching trough. At the
surface, the initial cold front is expected into northeast
Colorado between 00z and 06z Monday evening. Cold air will
continue pouring into the region through the day Tuesday, leading
to very cold days on Tuesday and Wednesday. Light snow will also
extend out onto the plains by late Monday night and Tuesday
morning. At this point, moisture levels don`t look to high, so
only light snow accumulations are expected.

The GFS and ECMWF models diverge in their solutions for Thursday.
The GFS has less amplitude and is therefore faster at moving the
cold air out of the region as a weak upper ridge moves over the
state. The ECMWF, with more amplitude in the flow pattern, brings
a second surge of cold air into Colorado by Thursday. This keeps
the Arctic airmass in place through Thursday, before moderating
temperatures on Friday. Will split the difference and show some
warming on Thursday, but still have temperatures below freezing
through Thursday afternoon.

&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 309 PM MST Fri Dec 2 2016

Main forecast challenge for the period will be ceilings with light
snow and mist through 03z. High chance of ILS approaches through
the afternoon as ceilings fluctuate between 020 and 030.
Visibility will diminish with the onset of light snow and mist
with down to 1sm possible. Winds will predominately be from the
ESE before turning south by 06z then veering around to drainage by
14z. Conditions will improve to VFR by 03z as snow diminishes
with the onset of subsidence later this evening.

&&

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

$$

SHORT TERM...Bowen
LONG TERM...Dankers
AVIATION...Bowen



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