Area Forecast Discussion
Issued by NWS Pueblo, CO

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FXUS65 KPUB 141217
AFDPUB

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

.SHORT TERM...(Today and tonight)
Issued at 513 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 bea lull in
snowfall over the continental divide region overnight...before
snow intensifies on Sunday. To keep highlight simple...highlights
were extended into Sunday. -PGW--

.LONG TERM...(Sunday through Friday)
Issued at 513 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 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.

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 12Z TAFS through 12Z Sunday morning)
Issued at 513 AM MST Sat Jan 14 2017

Mostly VFR at the TAF sites.  Precipitation will start moving into
the San Luis Valley late tonight and added some light snow to the
KALS TAF.  Precipitation will stay south of KPUB and KCOS until
after 12Z Sunday. --PGW--

&&

.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...PGW



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