Area Forecast Discussion
Issued by NWS Pueblo, CO

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FXUS65 KPUB 141735
AFDPUB

Area Forecast Discussion
National Weather Service Pueblo CO
1035 AM MST Sat Jan 14 2017

.SHORT TERM...(This afternoon through Sunday)
Issued at 652 AM MST Sat Jan 14 2017

Currently...skies are mostly cloudy over much of the CWA.  Radar
shows some echoes moving into western Colorado from the south. Tough
to see presence of snow on CDOT Wolf Creek webcam, but snow would
appear to be light at this time.

For today...southerly flow ahead of the cutoff off of Baja
California coast will continue to bring moisture into the area. See
no reason to change current highlights for the Continental Divide
region as deep southerly flow is favorable for the eastern San Juan
and La Garita Mountains. Orographics are not favorable for the
Sawatch range and will maintain advisory for this region.  Further
east...deep southerly flow will continue to bring moisture northward
to the eastern plains and eastern mountains.  Most of the forcing
will stay to the south of Colorado during the day and only
anticipate some widely scattered precipitation over the plains.
Precipitation could fall as some freezing rain or freezing drizzle
on the plains, but precipitation amounts will be very light.

Tonight...second round of precipitation will move northeast out of
New Mexico.  Currently looks as if most of the precipitation will
stay to the south and east of Colorado.  However, some precipitation
will move into the southeast plains of Colorado.  Currently, looks
as if the greatest amount of precipitation will be in Baca County.
Soundings are favorable for freezing rain and grids have up to 0.15
inches of icing for Baca County.  Decided to start the winter storm
warning for Baca County at 03Z...when freezing rain will start. Some
light freezing is likely over the remainder of the plains during
overnight.  Ice accumulations will generally be a few
hundreths...which is still enough to cause some slick roads.  Will
start winter storm warning for the remainder of the counties on the
eastern plains at 06Z due to the period of light freezing rain. Some
moisture will also move into the eastern mountains after midnight.
To keep the warnings simple, decided to start warning for the
eastern mountains and southern I25 corridor at 06z, but snow may
start a few hours later.  A third round of heavier precipitation
will move north of the New Mexico border with heavier precipitation
starting before 12z.  Freezing rain will continue to be a threat
over the eastern plains at this time.  Further west...there will be
a lull in snowfall over the continental divide region overnight...
before snow intensifies on Sunday.  To keep highlights
simple...highlights were extended into Sunday.  -PGW--

.LONG TERM...(Sunday night through Friday)
Issued at 652 AM MST Sat Jan 14 2017

...Winter storm to bring a variety of winter weather precipitation
to the plains...

A closed low currently spinning offshore southwest of San Diego CA
will move east and then northeast during the next couple of days.
The 500 mb low should be near south of San Diego by early this
evening, be south of Yuma AZ by tomorrow morning, southeast NM by
tomorrow early evening and then vcnty northeast OK/TX phdl by
Monday morning. A weak disturbance in advance of this low will
move across the southeast Plains of CO tomorrow morning. This
weather system will bring a variety of winter precip to the
plains, with the main concern being freezing precip for areas
generally east of La Junta to the KS state line.

WINTER STORM WARNINGS for snow and ice have been issued for most of
the plains mainly south and east of Pueblo. Most if not all of the
ICE will occur east of the I25 corridor region (mainly east of a La
Junta to Trinidad line. Winter weather hilites continue for the
mountains along the CONTDVD.

Sunday Morning...

The brunt of the heavier precipitation is fcst to be entering SE CO
from the south at 12Z tomorrow morning, and this band of heavier
precip is fcst to affect most if not all of the plains during the
morning hours on Sunday. This band of precip will likely bring 2-3
inches (or more) of snow to the greater I-25 corridor region and
some steady freezing rain to the plains generally from La Junta
eastward to the KS state line. The icing accumulation will increase
as one goes eastward from La Junta. Knowing exactly where the
snow/freezing rain line will be is difficult at best, but based of
model soundings...it appears to be around or just to the west of La
Junta.

It needs to be stressed that this will be the best time period for
heavier icing to occur over the eastern plains of Colorado. The
foliage is not accustomed to seeing icing, so there will be a good
chance of tree branches breaking and associated power outages.

Overall icing accumulations could reach up to 0.3" along the CO and
KS state line to less than 0.1 in the La Junta region.

Sunday Afternoon....

Heavier precip mostly moves out of the region, and a good part of
the plains will likely see only light precip during the afternoon
hours. the exception to this may be the far eastern plains where
some heavier freezing precip will be possible. The freezing
rain/snow line should advance eastwards as colder air on the
backside of the system begins to advance southeastward across the
plains. by late in the afternoon, flow at the ~700 mb level takes on
a more easterly component, and with the trough still to the
southwest, snow rates may increase on the eastern slopes of the
southern mountains and across the east slopes of the San Juans.

Since the flow will become more northerly by afternoon, areas that
are typically shadowed (i.e; S El Paso and N Pueblo counties) will
likely see the precip significantly decrease or possibly come to an
end.

Sunday Evening...

Flow at 700 mb become more easterly over the Plains of se Colorado
and this developing warm air advection pattern should allow for snow
to pick up over the far eastern plains. Additionally, the Raton Mesa
region will likely see an increase in snowfall as flow become
northeasterly over this region. Most of the precip by Sunday evening
should be snow over all of the plains.

Sunday night/early Monday morning...

700 mb circulation should be generally somewhere around extreme
southeast CO during this time. This will place most of the plains in
northeasterly to northerly flow. This will favor most of the far
eastern plains and Raton Mesa region for heavier precip. In addition,
the Palmer Divide (N El Paso county) may see some enhanced snowfall
during this time period, as both the 06 NAM and 00Z EC show an
enhanced QPF region over the Divide.

Monday morning (after sunrise)...

Storm begins to lift out and the trowal starts to pivot to the
northeast  Best snow at this time will likely be over east central
CO, and this may favor areas north of US 50 (generally east of La
Junta) for some steady snow. Northerly winds will begin to pick up
so some blowing snow will be possible. Some snow may also be
lingering over the east slopes of the southern mtns.

Monday afternoon into the evening hours...

Precip should be decreasing across the region, with the best chance
of snow over the far eastern plains and possibly the east slopes of
the southern Sangres and Raton Mesa.

Rest of the week...

Flow will transition to westerly with another long wave trough
moving across the region Thursday night and Friday. This will bring
an increasing threat of more snow to the contdvd starting mid week
and lasting into Friday. /Hodanish

&&

.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1021 AM MST Sat Jan 14 2017

Challenging CIG forecast for KALS and KCOS through tonight. With
storm system well off to the southwest...main influence with low
CIGS and VIS with -SN will come in later tonight...after 06z for
KALS...and after 09z for KPUB and KCOS as snow expands up from the
south. However...weak southerly flow aloft ahead of this system
could lead to sufficient upslope and moisture to produce some low
clouds at times at KALS today...as is occuring now...and at
KCOS after 02z this evening. Model guidance may not have a good
handle on this...so TAFs will bring in MVFR to IFR conditions for
both terminals early this evening. Best wave of snow with LIFR
conditions will spread in tonight.  -KT

&&

.PUB WATCHES/WARNINGS/ADVISORIES...
Winter Storm Warning from 11 PM this evening to 11 AM MST Monday
for COZ072>075-079-080-087>089-093>098.

Winter Storm Warning from 8 PM this evening to 11 AM MST Monday
for COZ099.

Winter Storm Warning until 5 PM MST Sunday for COZ068.

Winter Weather Advisory until 5 PM MST this afternoon for COZ060.

Winter Storm Warning until 5 PM MST this afternoon for COZ066.

&&

$$

SHORT TERM...PGW
LONG TERM...HODANISH
AVIATION...KT



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