Area Forecast Discussion
Issued by NWS Pueblo, CO

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FXUS65 KPUB 170652

Area Forecast Discussion
National Weather Service Pueblo CO
1152 PM MST Thu Nov 16 2017

Issued at 1150 PM MST Thu Nov 16 2017

Made adjustments to the overnight lows along the lee slopes of the
mountains, out into the I-25 corridor. Given the recent
observations, gusty winds and latest high-res model guidance,
raised overnight lows along and west of I-25, to the mountains,
where winds will remain elevated overnight. Near steady
temperatures, generally in the mid to upper 50s will prevail
through morning. No other changes were made at this time. Mozley


.SHORT TERM...(This evening through Friday)
Issued at 346 PM MST Thu Nov 16 2017

...Heavy snow and strong winds mountains...Damaging wind gusts
southern I-25 corridor...

Upper trough is starting to move onshore across the Pacific
Northwest with winds aloft strengthening over southern CO in advance
of this system.  Expect winds aloft to increase further and
especially on Friday with deep mixing as 120-140+ Kt upper jet
translates across southern CO by Friday afternoon.

Cross-sections still show quite a bit of forward shear overall,
though there could be a brief window for mtn wave development late
this evening through 12z across the southern I-25 corridor. However
main mechanism for gusty wind potential still looks to be tied to
deep mixing/brute forcing with surface pressure gradient on Friday
which could tap 40-50 kt winds not too far off the surface. All
parameters for high wind come together best across the southern I-25
corridor for Friday afternoon where gusts to around 60 mph will be
possible. However gusts anywhere along the I-25 corridor could hit
at least 50-55 mph on Friday. Will be upgrading the High wind watch
to a warning for the southern I-25 corridor, though latest high res
model runs are a little weaker with winds across eastern Las Animas
county, so will trim that section out. However, its important to
note that winds will be strong everywhere tomorrow. And while
humidity values are expected to remain above the critical threshold
of 15%, fire danger will still be elevated due to the potential for
such strong wind gusts.  This will be particularly true for the
southeast plains where fuels are critical.

Across the mountains...all advisories and warnings still look on
track.  Models differ most with how much snow will fall across the
Eastern San Juan mountains where 12z NAM was quite a bit heavier
than 12z GFS.  QPF from ECMWF better supports GFS solution which
would bode for lighter amounts, though still approaching low end
warning criteria.  Highlights over the mountains still look good and
made only some minor tweaks to accumulations.  Greatest impacts will
be across the Sawatch and Mosquito ranges.  Should be an active 24
hour period. -KT

.LONG TERM...(Friday night through Thursday)
Issued at 346 PM MST Thu Nov 16 2017

Friday night...A strong upper system will cross the Rockies Friday
with the trough axis finally exiting eastern CO early Sat morning. A
very tight pressure gradient coupled with a healthy slug of moisture
will continue snow and blowing snow across the higher elevations Fri
evening, with 3 to 5 inches of additional snowfall along the
Continental Divide possible by early Sat morning. Ongoing Winter
Storm Warnings and Advisories along the Divide look good through
12z, though much of the active snowfall will likely be rapidly
winding down by 09z. A surface cold front is forecast to drop south
across the Palmer Divide right around midnight, with winds becoming
northerly and remaining gusty across the plains during the overnight
hours. As for temps, expect minimum readings in the single digits
and teens for the mts and high valleys, and upper 20s to mid 30s for
the eastern plains.

Saturday through Monday...Ongoing forecast looks good for over the
weekend. The upper trough axis swings across the SE corner of the
state Sat morning, with just a few lingering showers over the E mts
early Sat morning. Sat still looks to be the coldest day of the
extended period, with highs only forecast to reach the 40s to around
50F. Otherwise, dry W-NW flow across the region is expected with
temps then climbing into the 50s to lower 60s Sun and Mon.

Tuesday through Thursday...Long range models are starting to agree
somewhat on a fast-moving weak disturbance bringing isolated showers
to the central mts on Tue, then high pressure over the CA Baja
nosing up across the desert SW and keeping things dry and mild for
Wed and Thu. Moore


.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1039 PM MST Thu Nov 16 2017

VFR at all taf sites tonight and Friday. Expect periods of very
strong W-SW winds at all terminals overnight and through the day
Friday, with gusts 30-40 kts at times. Cold front then drops south
through the area Fri evening, with a switch to more W-NW winds at
most locations 02z-04z. Over the mts, Continental Divide will be
obscured by low clouds and snow the next 24 hrs, with IFR to LIFR
conditions. Eastern mountains may see occasional -shsn Fri
evening, with peaks occasionally obscured.


Winter Weather Advisory until 5 AM MST Saturday for COZ059-063-

Winter Storm Warning until 5 AM MST Saturday for COZ058-060-061-

High Wind Warning until 5 PM MST Friday for COZ087-088.



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