Area Forecast Discussion
Issued by NWS Pueblo, CO

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FXUS65 KPUB 012155

Area Forecast Discussion
National Weather Service Pueblo CO
255 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 digging south into
southern Arizona and southern New Mexico by tomorrow afternoon.

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 Critso 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 00Z TAFS through 00Z Friday evening)
Issued at 255 PM MST Thu Dec 1 2016

A broad upper trough digging into the Great Basin will slowly spread
light snowfall across the State late tonight and through the day
tomorrow. Not expecting much if any snowfall at the taf sites
through 18Z Friday though will see clouds thickening and lowering
tonight through the day tomorrow.

VFR conditions expected at COS and PUB through 18Z Friday, with MVFR
and possible IFR conditions in light snow or flurries developing aft
18Z. ALS could see MVFR cigs developing after 06Z FRI with MVFR and
IFR conditions possible aft 18z with overrunning light snowfall.
Any snow accumulations at the terminals, mainly ALS and COS, is
expected to less than 1 inch.




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