Area Forecast Discussion
Issued by NWS Pueblo, CO

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950
FXUS65 KPUB 200659
AFDPUB

Area Forecast Discussion
National Weather Service Pueblo CO
1159 PM MST Mon Feb 19 2018

.UPDATE...
Issued at 1159 PM MST Mon Feb 19 2018

Updated forecast to increase intensity/coverage of snow into the
early morning hours.

UPDATE Issued at 938 PM MST Mon Feb 19 2018

Banded snow along and east of the mountains onto the plains has
been rather vigorous this evening, with spotty 1-3 inch accums
already from Pueblo up into nrn El Paso County. Still have a
couple hrs to go before bands shift east and begin to dissipate,
so have increased pops along I-25 and portions of the plains,
with another inch or two of snowfall possible, mostly before
midnight.

&&

.SHORT TERM...(This evening through Tuesday)
Issued at 325 PM MST Mon Feb 19 2018

...Strong winds and Heavy snow to continue across the southwest
mountains tonight...

Mean trof across the Great Basin will continue to gradually shift
eastward towards western CO overnight.  First round of energy will
be lifting out across CO in strong southwest flow aloft this
evening.  Its been snowing hard across the southwest mountains
through the day given strong orographics.  Visibilities have been
abysmal at times across Wolf Creek Pass and La Manga Pass.  Even
Cochetopa Pass in the La Garitas has seem some poor visibilities at
times but overall looks like there has been less snow the farther
north one goes. Winter weather highlights across the mountains still
look on target.  Even seeing some isolated thunder across southwest
CO...so locally intense snowfall with convective snow bursts will be
possible.  Have introduced some thunder into the grids to account.
Overall another foot of snow looks likely across the eastern San
Juans by morning with lesser amounts for the Sawatch/Mosquito and
crest of the Sangres and Pikes Peak.

Meanwhile...lapse rates steepen aloft late this afternoon through
tonight and already seeing convective snow showers across the
southeast mountains, a few of which are developing/spreading into
the adjacent plains.  Gusty winds will be the main concern with
these over the mountains...but as they shift eastward over the
arctic airmass in place across the plains...this threat will be less
likely.  High res models have caught on to farther south position of
the front across the plains and suggest convective snow showers will
override the cold air across the far eastern plains this evening.
They will be moving pretty fast though and this should help limit
accumulations.  But locations to watch will be Kiowa and possibly
Prowers counties later this evening. A quick inch of accumulation
would not be out of the question. Otherwise...precipitation should
wind down quickly for most of the plains overnight although
retreating cold front will make another southward push through the
plains overnight and will likely see stratus break but reform and
lower again towards early Tuesday morning across the plains.  Always
difficult to say what the extent of any flurries, or freezing
drizzle/fog will be behind the front. Models have had a tough time
capturing the southern penetration of the front and depth of cold
air lately and today was no exception.  Have introduced some low
pops along/north of highway 50 late tonight/early Tuesday
morning...though suspect that drying aloft may limit precipitation
efficiencies more so tomorrow morning. Upper trof lingers across the
great basin and western CO on Tuesday as more energy drops in from
the Pacific northwest. Moisture shallows out quite a but, though it
will still remain unstable enough to maintain scattered pops along
the Continental Divide. Another impulse lifts out across the area
during the afternoon...and with continued southerly upslope into the
Palmer Divide, the Pikes Peak region may see some more light snow
during the afternoon as snow showers develop over the mountains and
spread eastward. Overall, accumulations look light. Dropped MaxT
forecast across the plains quite a bit, anticipating a farther south
cold front position and less warming than guidance suggests.  -KT

.LONG TERM...(Tuesday night through Monday)
Issued at 325 PM MST Mon Feb 19 2018

Tuesday night and Wednesday...As the upper trough axis swings east,
pcpn is forecast to come to an end over the central mts and Pikes
Peak region Tue night around midnight, while light upslope flow
across the plains will keep the east chilly. As the next upper
shortwave approaches from the west late Wed afternoon, isolated snow
showers return to the continental Divide. West to southwest winds
across the higher elevations will remain breezy to strong, while the
lower elevations will remain under cool easterly flow. Highs are
expected to only climb into the upper 20s to upper 30s for most
locations.

Thursday and Friday...The next upper low pressure system drops out
of the Pacific NW and crosses the Great Basin on Thu, then sweeps
across the region on Fri. The GFS and EC models disagree on
placement of this low, with the GFS placing this system farther
south which would have a greater impact on the cwa into the weekend.
Since the models differ on low placement but agree on a system
moving across the region during the same time frame, will hold with
high pops for the mts areas starting late Wed night through Fri,
then isolated pops for the plains Thu and Fri. as the location gets
pinned down better over the next day, the forecast will become more
specific on snow amounts and location. Look for highs in the 30s to
lower 40s for the high valleys, and 40s to mid 50s for the plains.

Saturday through Monday...Plenty of upper level activity to keep
Colorado occupied over the weekend, though beyond Friday the models
are having a very tough time deciphering the upper track. Will keep
the mention of snow over the central mts over the weekend because
that seems to be a safe bet under this pattern, and partly cloudy
skies elsewhere. Extended models are not indicating any llvl cold
air intrusions for the east, so look for max temps each day in the
upper 30s to mid 40s for the high valleys, and mid 40s to mid 50s
for the plains. Moore

&&

.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1030 PM MST Mon Feb 19 2018

Light snow will come to an end 08z-10z at KCOS and KPUB, although
IFR conditions may linger through the morning and into the afternoon
Tue as weak easterly winds keep low clouds and patchy fog in
place. Gradual improvement to VFR then expected from late
afternoon into the evening at both sites. At KALS, VFR expected
overnight and through the day Tue, with sw winds continuing to
gust in the 20-30 kt range through most of the next 24 hrs. Over
the mountains, IFR widespread with snow and low cigs, some
vis improvement expected late Tue as snow diminishes, though most
higher terrain will remain obscured by clouds into the evening.


&&

.PUB WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 8 AM MST Tuesday for COZ058-061-
065>067-073-075-082.

Winter Storm Warning until 8 AM MST Tuesday for COZ060-068.

&&

$$



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