Area Forecast Discussion
Issued by NWS Pueblo, CO

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FXUS65 KPUB 100527
AFDPUB

Area Forecast Discussion
National Weather Service Pueblo CO
1027 PM MST Fri Dec 9 2016

.SHORT TERM...(This evening through Saturday)
Issued at 244 PM MST Fri Dec 9 2016

Cold air retreating from southern Colorado today with 50s reappearing
in the lee of the eastern mountains. Western mountains and interior
valleys remain seasonably cold, while unmixed locations in the
lower Ark Valley from Pueblo eastward have struggled to reach the
low 40s under light SE winds. Snowfall has tapered off to just
flurries over the central mountains, though clouds still linger
over the higher peaks from Monarch Pass northward. Overnight,
westerly flow aloft will continue, with occasional bouts of high
level cloudiness across the area. Overnight lows will be
seasonably cold most locations, though eastern mountain slopes and
areas along/west of I-25 will stay somewhat mixed, keeping lows
within a few degf of 32f.

On Saturday, upper jet begins to sag southward, bringing snow back
to the Central Mountains by afternoon. Will start the winter storm
watch in the mid-afternoon, though heavier snow and strong winds
will likely hold off until after sunset. Farther east, main
concern is potential development of strong downslope winds,
especially in the lee of the Sangre de Cristo range during the
late afternoon. Mountain wave sets up after 21z and shear profile
looks favorable with strong reverse shear toward 00z as 700 mb
winds increase to 60-70 kts. No highlight yet by bears watching.
Elsewhere, mild temperatures and breezy to windy conditions will
continue, with afternoon highs well above average.

.LONG TERM...(Saturday night through Friday)
Issued at 244 PM MST Fri Dec 9 2016

Not much change to the forecast thinking with good model agreement
and generally low ensemble spreads through the extended.  There will
be two upper disturbances, Sunday and again Tuesday, that will bring
increased mountain snow.  In addition, periods of strong winds will
be possible.

Saturday night through Sunday...a quick moving upper disturbance is
forecast to move out of the Northern Rockies, southeast into the
Central Plains.  This will bring a period of moderate to heavy
snowfall to the Continental Divide, especially the Central
Mountains.  The heaviest snow is expected late Saturday night into
Sunday morning.  Snow accumulations of 12 to 18 inches are expected
over the Central Mountains.  South of Monarch Pass, less favorable
orographic flow will bring less snowfall to the La Garita and San
Juan Ranges, where 2 to 6 inches, and locally higher amounts, will
be possible.  In addition to the snowfall, strong westerly winds
will move across Colorado.  Mountain top winds may gust well in
excess of 60 mph.  Shear profiles indicate the potential for
downslope winds in the lee of the Eastern Mountains, especially
south of Pueblo late Saturday night into Sunday morning.  This will
need to be monitored closely.  The upper disturbance will quickly
shift east of the area by Sunday afternoon.  This should allow snow
to decrease over the Continental Divide, with light snow persisting
into Monday morning, however additional accumulations are expected
to be minor.  Temperatures Saturday night will depend on mixing,
with areas in the lee of the Eastern Mountains likely staying pretty
warm.  Afternoon highs on Sunday will reach the lower 50s for the
Plains.

Monday...zonal flow aloft will remain across Colorado on Monday.
Light snow will persist through the day into Tuesday along the
Continental Divide.  Minor accumulations of an inch or two will be
possible.  Strong winds will remain possible over the higher
elevations.  Afternoon highs will reach into the upper 40s to lower
50s across the lower elevations.

Tuesday and Wednesday...the next upper level disturbance is forecast
to move across the area midweek.  Expect another round of moderate
to heavy snowfall for the Continental Divide beginning Tuesday. This
disturbance appears to have a more southerly track, which would
indicate better chances for snowfall for the Eastern Mountains on
Tuesday into Wednesday.  A cold front is forecast to drop south late
Tuesday night across the Plains.  This will shift flow upslope
easterly with a period of precipitation on Wednesday across the
Plains.  Locations of the Palmer Divide and along the lee slopes of
the Eastern Mountains will be favored for a period of snow, while
areas further east will only see light snow.  Expect snowfall to
come to an end Wednesday evening as the upper disturbance moves east
of the area.  Temperatures Tuesday will reach the 40 across the
Plains, while Wednesday will be much colder with highs struggling to
reach 30.

Thursday into Friday...flow aloft will weak with flat upper ridging
moving out of the western CONUS into the Central Plains, while an
upper trough forms off the west coast.  Expect a few light snow
showers over the Central Mountains Thursday.  Flow will transition
southwest by Friday, as energy from the system out west moves into
western Colorado.  This should bring another round of increased
snowfall for the Continental Divide for late week. Mozley

&&

.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1027 PM MST Fri Dec 9 2016

VFR conditions with breezy south to southwest afternoon winds of
15-25kts expected at COS, PUB and ALS over the next 24 hours.
Stronger westerly winds will be possible across the lower eastern
slopes of the southern front range later in the taf period, ahead
of a weather system expected to move across the state tomorrow night.

&&

.PUB WATCHES/WARNINGS/ADVISORIES...
Winter Storm Watch from Saturday afternoon through Sunday
afternoon for COZ058-060.

&&

$$

SHORT TERM...PETERSEN
LONG TERM...MOZLEY
AVIATION...MW



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