Area Forecast Discussion
Issued by NWS Pueblo, CO

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165
FXUS65 KPUB 182246
AFDPUB

Area Forecast Discussion
National Weather Service Pueblo CO
346 PM MST Sun Feb 18 2018

.SHORT TERM...(This evening through Monday)
Issued at 346 PM MST Sun Feb 18 2018

...Damaging wind gust potential increasing for the southeast
mountains...Wet Mountain Valley and southern I-25 corridor...

...Critical fire weather conditions continue through 6 PM for the
lower elevations of the southeast mountains and plains...

High impact weather expected in the short term...mainly in the form
of wind at the outset.  Have extended high wind warnings for the
higher peaks and the Wets, Sangre De Cristos, Wet Mountain Valley
and southern I-25 corridor in Huerfano county through tonight and
Monday morning.  Model cross-sections show another potential round
of mountain wave activity this evening through the overnight
hours...with high res models suggesting the western Wet Mountain
Valley and the lee of the southern Sangre De Cristo mountains could
be hit the hardest.  The farther south one goes, the better the
cross-sections look, and NAM soundings show a decent mountain top
inversion around the TAD area which is not as pronounced as far
north as PUB. Gusts to around 85 mph or even a little more will be
possible if the local 4 km WRF is correct for the mountains...with
gusts to around 65 mph for the adjacent lower elevations. Forward
shear increases Monday afternoon so although mountain peaks will
continue to gust...gusts over the lower elevations shouldn`t be
quite as strong.

Moisture will feed into the southwest mountains this evening with
snow ramping up across the Continental Divide after midnight.
Heaviest snow will fall through Monday into Monday night.  Still
looking at up to 18 inches through Monday afternoon for the Eastern
San Juan mountains with up to 8 inches across the Sawatch range.
Lesser amounts will be possible for the La Garita mountains.  Host
of Winter Weather Advisories and Warnings still look good.  Upgraded
the Sawatch range to a Winter Storm warning as there will be
considerable blowing snow associated with this system which could
result in a greater impact to travel than what snow totals suggest.
Additional snow will fall Monday night into Tuesday...see discussion
below for more details.

As the upper trof approaches western CO Monday afternoon...the
Sangre De Cristo mountains and top of Pikes Peak will get into the
action, as spill over moisture upslopes along the western slopes and
over the Peaks.  The southern San Luis valley will also pick up an
quick inch or two along the valley edges during the afternoon.

Across the plains a cold front will drop through during the morning
and will likely hang up just south of highway 50.  To the north of
this front expect a sharp temperature gradient with temperatures
possibly topping out in the 40s. Nudged temperatures down several
degrees over model blends and guidance values...and appears NamNest
may be picking up on this best.  Later shifts may need to nudge
temperatures down further.  Meanwhile...southern I-25 corridor and
southern portions of the plains could see near critical fire weather
conditions return as gusty southwest winds spread across the area
during the afternoon.  It appears that relative humidity values will
come up just shy of the 15% or lower threshold needed for a Red Flag
Warning, so will hold off for now...however fire weather threat will
remain elevated. -KT

.LONG TERM...(Monday night through Sunday)
Issued at 346 PM MST Sun Feb 18 2018

...Pacific Conveyor Belt will keep an active pattern in place for
Colorado...

Monday night and Tuesday...Strong upper level trough will sweep
across the region through Tue, bringing heavy snow and blowing snow
to the higher terrain, and predominantly wind to the eastern plains.
The trough axis is forecast to be over the Great basin Mon night,
with a very strong upper jet carving out the base of the trough and
laying across the Four Corners and Continental Divide. As the trough
continues east on Tue, snowfall will begin to diminish by midday.
Total snow amounts vary, but localized 1 foot amounts will be
possible for the mts, and up to 2 feet for the sw mountains. In
addition wind gusts of 55 to as high as 70 mph will be possible, so
travel will be difficult at times over mt passes. Another tough
aspect of the forecast through Tue will be the temps. A cold front
will drop south to the Palmer Divide Mon night, but models disagree
on whether this front will continue south, or stall until early Tue
morning. Positioning of the front will dictate what the overnight
lows will be Mon night. Currently, forecast lows are in the teens
for the high valleys and along the Palmer Divide, and 20s for the
remainder of the plains. Highs on Tue will be in the upper 20s and
30s, to around 40F near the Raton Mesa.

Wednesday...Light upslope flow across the plains will keep
temperatures cool, but much of the upper dynamics will have moved to
the east so look for dry conditions through the day. As the next
upper trough approaches from the west Wed night, isolated snow
showers return to the continental Divide. Highs are expected to only
climb into the upper 20s and 30s, to perhaps around 40F across the
southern foothills, which is nearly identical to Tue.

Thursday through Sunday...Models show multiple upper shortwaves
dropping out of the Pacific Nw, crossing the Great Basin and
streaming across Colorado through the extended period. This conveyor
belt of activity should provide an almost daily shot of snow for the
higher terrain, while keeping the eastern plains mainly dry and
breezy. However, models do not necessarily agree on timing, so
pinning down exact timing of these systems will be problematic. Look
for highs each day in the upper 30s and 40s for the high valleys,
and 40s to mid 50s for the plains. Moore

&&

.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 346 PM MST Sun Feb 18 2018

Gusting winds will be an issue for all forecast points. During the
morning hours, a cold front will move over KCOS and KPUB from the
northeast.

KALS: Consistent southwesterly winds throughout the forecast period.
Tomorrow evening around the 00z hour, snow will begin to fall across
the San Luis Valley. After the 00z hour tomorrow, CIGs will likely
drop.

KCOS: The cold front will propagate over KCOS in between the hours
of 10 to 12Z. After the cold front moves over KCOS, lower cloud
ceilings are likely to lower CIGs in the morning hours. Conditions
should improve during the afternoon hours, but there will still be a
stratus deck over KCOS.

KPUB: The cold front will propagate over KPUB in between the hours
of 11 to 13Z. Similar to KCOS, lower cloud ceilings are likely to
lower CIGs in the mornings hours. Conditions should improved during
the day, but a stratus deck will remain over KPUB.

Skelly

&&

.PUB WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning until 6 PM MST this evening for COZ222-225>237.

High Wind Warning until noon MST Monday for COZ072>075-078>080-
082-087.

Winter Weather Advisory from 11 PM this evening to 8 AM MST
Tuesday for COZ058-061-065>067.

Winter Weather Advisory from 2 PM Monday to 8 AM MST Tuesday for
COZ073-075-082.

Winter Storm Warning from 11 PM this evening to 8 AM MST Tuesday
for COZ060-068.

&&

$$

SHORT TERM...KT
LONG TERM...MOORE
AVIATION...KT



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