Area Forecast Discussion
Issued by NWS Pueblo, CO

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FXUS65 KPUB 272153
AFDPUB

Area Forecast Discussion
National Weather Service Pueblo CO
353 PM MDT Mon Mar 27 2017

.SHORT TERM...(This evening through Wednesday) Issued at 245 PM
MDT Mon Mar 27 2017

...Heavy snow for the southeast mountains and I-25 corridor Tuesday
Night through Wednesday...

Upper trof progged to dig southward through the Great
Basin...closing off south of the 4 corners region before translating
eastward across NM on Tuesday.  There are still some variances
between the models on the track of the upper low...with NAM and
ECMWF a tad farther south than the GFS.  NAM and GFS merge solutions
Tuesday night with the upper low centered over NE NM...while ECMWF
keeps it farther south. Upper low then drops southeastward again
into the TX panhandle by Wednesday evening with ECMWF farther east
into western OK.  Needless to say...there are still some
uncertainties with QPF across southern CO.  GFS is a farther north
with the heavier QPF axis on Wednesday...and looks a little too far
north even given the position of the upper low.  Have shaded grids
closer towards the NAM and ECMWF solution for now.  Another
potential uncertainty is how much cold air comes in with the system.
NAM drops snow levels down to around 6000 feet...perhaps briefly
down to 5500 feet Wednesday morning.  GFS would suggest higher snow
levels.

So for sensible weather...should see rounds of snow on the WAA side
of the storm spread through the mountains along the Continental
Divide tonight.  Southwest mountains may fair best initially given
the upslope flow component tonight.  Should see the next round come
in Tuesday which should blossom across the southeast mountains and
plains during the afternoon as upper low comes into a more favorable
position.  Initially snow levels will start out high...around 9000-
9500 feet.  However snow levels should drop during the
evening...hitting the top of the Palmer Divide towards 06z...and
possibly as far down as 5500-6000 feet by Wednesday morning.  This
is a tad higher than what the 12z runs had shown.  Strong NE flow
Tuesday night should provide favorable upslope flow for the Wets and
Sangre De Cristo Mountains into Wednesday where snowfall totals
should range in the 1-2 feet...with some areas seeing up to 3 feet.
Southern I-25 corridor is the most problematic as models suggest
temperatures may hover around or slightly above freezing through the
day on Wednesday.  Suspect with the farther south solution that snow
levels will get driven down closer to what the NAM is suggesting.
Thus have decided to go out with a Watch for the southern I-25
corridor from Walsenburg to the Raton Ridge.  Pueblo and most of the
southeast plains looks to stay all rain with this event now...with
healthy amounts of QPF through the period...likely ranging from
around .75 to 1.5 inches...and up to 2 inches to 2.5 of water for
portions of the Wets and Sangres.  Overall a very wet event for
southern CO.  Precipitation will shift off to the southeast through
the late afternoon and evening and suspect most of the impacts to
the Pikes Peak region will wind down during the afternoon...
especially if more southern ECMWF works out.

Some important differences between this storm and the one last
week...this one looks less windy.  Southeast plains/I-25 corridor
could see some 20 to 40 mph gusts...but this is a far cry from last
weeks event where winds gusted over 60 mph.  This one looks more
snowy...especially for the Wets and Sangres.  Another concern will
be convective potential for Tuesday. There is sufficient CAPE for a
strong storm or two. Main concern will be for heavy rainfall on the
lower slopes of the burn scars Tuesday afternoon.  If this occurs
some enhanced run-off or flash flooding would be possible. The risk
will lessen into the evening as snow levels drop.
-KT

.LONG TERM...(Wednesday night through Monday) Issued at 245 PM
MDT Mon Mar 27 2017

Active weather will continue through the next week with the
potential for very heavy mountain snowfall and several inches of
rainfall possible across the Plains. There is some model
discrepancies with the finer details, but the overall pattern will
be busy.

Wednesday night...the upper level low is forecast to continue to
move northeast out of Oklahoma into Missouri by Thursday morning.
Expect mountain snow to come to an end during the evening hours.
Out on the Plains, showers, possibly mixed with light snow will
clear into Kansas by morning. Additional accumulations over the
mountains will be minor, with no accumulations expected over the
Plains. Overnight lows will fall into the lower 30s with near
freezing conditions across the Plains.

Thursday...shortwave upper ridging is forecast to move out of Utah
and across Colorado into the Central Plains by the evening ahead
of the next upper level storm system. Generally dry conditions
will prevail through much of the day. The exception will be along
the Continental Divide as flow transitions southwesterly and
moisture begins to move back into Western Colorado. Highs will
reach into the lower to mid 60s.

Thursday Night through Sunday...the next strong upper level storm
system is forecast to drop south across the Great Basin and then
slowly progress eastward into the Texas Panhandle through the
weekend. The current storm track brings very favorable flow to
Southern Colorado with wrap around easterly flow across the
region for a prolonged period. Abundant moisture and lift across
the region will set the stage for heavy mountain snowfall, and
moderate to heavy rain along the Eastern Mountain lee slopes and
the Eastern Plains. Another 1 to 3 feet may be possible in the
mountains. The Plains will likely see another 1 to 2 inches of
rainfall. Current model projections have the heaviest
precipitation falling on Saturday. Snow levels will once again be
tricky, initially starting out about 9 kft, and falling to around
6 kft over the weekend. Temperatures will be cool with 40s to
50s.

Monday and beyond...we will likely see a brief break on Monday as
the weekend storm system moves off to the east, and the next
storm system drops south out of the Pacific Northwest. A few
showers will be possible by Monday afternoon over the mountains,
spreading east Monday night. Several storm systems will continue
into next week, with one Tuesday into Wednesday, and another
towards the weekend. Mozley

&&

.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 245 PM MDT Mon Mar 27 2017

VFR conditions expected this evening...though there is the potential
for some brief IFR late tonight at KCOS if some patch stratus can
develop. Right now the probability looks fairly low.  Winds this
evening will decouple though will increase again on Tuesday out of
the east.  Rain and high mountain snows will blossom over the
mountains as the system approaches Tuesday afternoon with the
heaviest precipitation spreading into the terminals during the
evening and overnight.  Widespread IFR to LIFR conditions can be
expected Tuesday night through Wednesday.  Event should stay as rain
at KPUB...but KCOS and KALS could see 1-3 inches of snow at the
terminals Tuesday night-Wed morning. -KT

&&

.PUB WATCHES/WARNINGS/ADVISORIES...
Winter Storm Watch from late Tuesday night through Wednesday
afternoon for COZ084-087-088.

Winter Storm Watch from Tuesday evening through Wednesday
afternoon for COZ072-074-079-081.

Winter Weather Advisory from 6 PM this evening to noon MDT
Wednesday for COZ058-060-066-068.

Winter Storm Watch from Tuesday afternoon through Wednesday
afternoon for COZ073-075-080-082.

&&

$$

SHORT TERM...KT
LONG TERM...MOZLEY
AVIATION...KT


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