Area Forecast Discussion
Issued by NWS Pueblo, CO

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FXUS65 KPUB 232144
AFDPUB

Area Forecast Discussion
National Weather Service Pueblo CO
344 PM MDT FRI SEP 23 2016

.SHORT TERM...(This evening through Saturday)
Issued at 301 PM MDT Fri Sep 23 2016

...A variety of high impact weather to continue across southern CO...

An intense upper low over NW UT/SW WY will continue to lift
northeastward with trailing trof axis swinging across southern CO
during the evening hours...a little behind earlier model
projections. This will put the brunt of the energy crossing the
eastern mountains between 00z and 03z with strong downward forcing
coming in quickly behind. Dry line has been slow to sharpen
up...though in last hour dew point at COS plummeted from 39 to 15
degrees F...so once winds shift out of the southwest to west...it
shouldn`t be too long before rapid drying takes place. Winds have
been gusting to 40-50 mph at times and this will continue through
the evening and overall Red Flag Warning still looks on track.  To
the east of the dryline...high res models are developing a broken
line of thunderstorms between 4 PM and 5 PM. Dew points in the lower
50s yield mixed layer CAPE values of 1000 J/kg in SPC meso analysis.
Deep layer shears will be running around 30-40 kts...so potential
for one or two severe thunderstorms across the eastern counties
still looks possible. Storms will be moving rapidly north
northeastward with HRRR showing most of the activity done by 06z.
Given high based nature to thunderstorms...main threat still looks
to be winds over 60 mph and hail to around 1 inch in diameter.

As the upper low lifts northeastward should see activity tail off
from west to east...though northern portions of the Continental
Divide may continue to see off and on snow showers through the
overnight hours.  Cold front moves in overnight...and a widespread
freeze still looks likely for the San Luis Valley. Have upgraded the
freeze watch to a freeze warning. Temperatures will be cooler
elsewhere...but winds should keep temperatures from dropping too
close to the freezing mark.

Saturday will be cooler behind the front...though secondary push of
cooler air will approach the Palmer Divide during the afternoon.
Just enough moisture will be present along the CONTDVD and northern
portions of the southeast mountains for some isolated to scattered
showers and thunderstorms to redevelop...but overall...any
precipitation looks light at this point. -KT

.LONG TERM...(Saturday night through Friday)
Issued at 301 PM MDT Fri Sep 23 2016

...Feeling more like Fall on Sunday...

The global models have come into better agreement today. The
strong upper low moving through W CO today will split this
weekend, with most of the energy lifting off to the NE. The base
of the trough will cut off over W NM, then slowly eject to the NE
during the mid to latter portion of the coming week.

Sat night...the main low will be well north of our area...over
the Nrn High Plains, while the trough axis is moving through E CO
and the base of the trough beginning to split and cut off over NM.
This will be the coldest air mass of the extended, with H7 temps
getting down to around zero degrees over Teller County by early
Sun morning. So...there could be a few snow showers above 9000
feet early Sunday, and possibly some light localized accums...but
significant or widespread snow appears unlikely, and the latest
model trends are for less QPF over the area.

Main impact from this system will be considerably cooler wx on
Sunday, with high temps only in the 60s for the Plains and 40s
for the mts. WIll clear out pretty quickly Sun morning-afternoon,
leaving our area with building high pressure from the west, which
will keep us dry through at least Tuesday. Temps will gradually
increase during this time period.

By early Wednesday, the cut-off low to our south will finally
begin moving into SW CO. This system will be much weaker than the
current upper low, and with the Southwesterly trajectory, will
also be quite a bit warmer aloft. So, snow levels will likely stay
pretty high for the last week in September, generally above 12000
feet. Showers will be on the increase, especially for the latter
part of Wed into early Thu. Have left mention of TS in the grids
for this period since there will be some modest instability with
the upper low. But for the balance of the forecast period,
climatology does not favor widespread TS, so left any precip as
Showers for the rest of this period.

Once the second upper low moves through from the SW, our area will
likely stay in an unsettled pattern with shortwaves moving through
the Central Rockies. Current forecast assumes southwest flow over
the CWA, so temps will remain generally above average. Rose

&&

.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 301 PM MDT Fri Sep 23 2016

South winds 25-40 KTS will shift around from the west during the
late afternoon and early evening and remain gusty through 03-04z
before gradually diminishing.  TAF sites will remain VFR...but
CONTDVD region will see off and on IFR to LIFR conditions in SHRASN
through the early evening. Isolated TSRA will be possible to the
east of the KLHX this evening...with the potential for a strong to
severe storm or two through the evening hours.  Clearing will take
place through the evening...though some IFR to MVFR stratus may
persist along the CONTDVD through Saturday morning.  Winds will be
much lighter on Saturday with another cold front expected to drop
through the plains late Sat afternoon and early Sunday evening. -KT

&&

.PUB Watches/Warnings/Advisories...
Red Flag Warning until 8 PM MDT this evening for COZ226>233.

Freeze Warning from midnight tonight to 9 AM MDT Saturday for
COZ069>071.

&&

$$

SHORT TERM...KT
LONG TERM...ROSE
AVIATION...KT



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