Area Forecast Discussion
Issued by NWS Pueblo, CO

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FXUS65 KPUB 020530

Area Forecast Discussion
National Weather Service Pueblo CO
1030 PM MST Thu Dec 1 2016

.SHORT TERM...(This evening through Friday)
Issued at 255 PM MST Thu Dec 1 2016

...A quick shot of light snow Tomorrow...

Current water vapor imagery and upper air analysis indicating a
broad upper trough across the intermountain west with secondary
energy digging down the backside of the system across the Pac NW
Coast at this time. Water vapor and regional satellite imagery also
indicating mid and upper level moisture slowly spreading east across
the Great Basin and into western Colorado, with regional radars also
indicating some light snow showers moving across northwestern
Colorado at this time. Temperatures have warmed into the mid 30s to
mid 40s across the eastern plains this afternoon, with mainly 20s
and 30s across the higher terrain at this time.

Tonight and Friday...12Z runs of the NAM and GFS are in fairly good
agreement with previous runs of the GFS and ECMWF (with the 12Z run
of the EC not available at this time) all pointing to a weak and
broad upper trough translating across the Rockies through the day
tomorrow, as most of the energy with this system digs south into
southeastern Arizona and southwestern New Mexico by tomorrow

With that said, could continue to see some light WAA snow showers
across the higher terrain, especially along and west of the ContDvd
tonight. Chances of generally light snow increase again over the
higher terrain of the ContDvd early Friday morning with precip
chances spreading south and east through the afternoon. Available
moisture slowly increases across the area tomorrow, though with not
much in the way of orographics and with only weak lift associated
with the broad trough, just expecting light precipitation through
the day tomorrow. Best accumulations will favor areas over and near
the higher terrain, especially over and eastern San Juan and
southern Sangre de Cristo mountains, where could see 1 to 3
inches of snow through the afternoon. Light snowfall of an inch or
less will also be possible across the rest of the higher terrain
and lower eastern slopes along and west of the I-25 corridor.
Overnight lows to be slightly warmer than last night, with
increasing clouds expected from west to east, with highs tomorrow
in the 30s to near 40 across the lower elevations and mainly teens
and 20s across the higher terrain.

.LONG TERM...(Friday night through Thursday)
Issued at 255 PM MST Thu Dec 1 2016

Splitting western U.S system will drop majority of the energy
southward into southern AZ and old Mexico Friday evening with upper
trof axis slowly moving across CO Friday night/early Saturday.
Eastern San Juan mountains should fair the best with another couple
inches of light snow Friday evening.  Still some question as to how
much snow will fall across the plains Friday night as area comes
under weak warm air advection pattern.  NAM is the heaviest handed
with snowfall showing widespread trace to an inch of snow across the
area...with best chances south of highway 50.  GFS is drier
suggesting just a trace of snow for most areas...with up to half an
inch across the southern border.  Either way this looks like a light
precipitation event for the southeast mountains and plains so will
maintain scattered pops as far north of highway 50 for now with
likely pops for the eastern San Juans and southern Sangre De Cristo
mountains. Temperatures will be colder for Friday with readings
topping out mainly in the 30s across the lower elevations...with a
few lower 40 degree readings near the KS border.

Drier weather and moderating temperatures expected for the weekend
as flow aloft transitions to zonal.  Sunday still looks like the
warmest day with temperatures returning to around 50 across the

Next upper trof carves out over the northwestern U.S on Monday.  GFS
is quicker in sending a cold front into southeast CO during the
afternoon with upper jet dynamics spreading snow across northern CO.
EC and Canadian were a little slower spreading the cold air
southward...but do so by Tuesday.  Still up in the air with the
timing and amplitude of the upper level trof as it moves across CO
Tuesday/Tuesday night. ECMWF has been consistently more amplified
than GFS and would suggest a moderate snowfall for the southeast
mountains and plains.  GFS`s farther north solution is drier.  But
all models suggest an intrusion of arctic air with this next front
which should drop temperatures dramatically across southern CO
through mid week.  This should also yield pretty high snow ratios
meaning snowfall would be the dry fluffy type.

System stays pretty progressive with upper level ridging for later
in the week which should slowly moderate temperatures. -KT


.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1023 PM MST Thu Dec 1 2016

At the taf sites, expect VFR conditions overnight, then gradually
lowering cigs during the day Fri. Light snow will develop after
18z, with a period of IFR cigs/vis in the late afternoon and early
evening all sites. Snow then gradually ends Fri evening, with
clouds lifting at KALS and KPUB and conditions becoming VFR 02z-04z.
Snow will end at KCOS shortly after 00z as well, though with a
light SE wind until until 06z-08z, suspect lower clouds will be
slow to clear near the terminal and will keep at least some MVFR
stratus in place until 06z. Over the mountains, periods of -shsn
will continue overnight and through Fri, with peaks and high
mountain passes generally obscured through the period.




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