Area Forecast Discussion
Issued by NWS Pueblo, CO

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FXUS65 KPUB 262137

Area Forecast Discussion
National Weather Service Pueblo CO
337 PM MDT Wed Apr 26 2017

.SHORT TERM...(This evening through Thursday)
Issued at 337 PM MDT Wed Apr 26 2017

Weak upper wave and modest instability producing a few showers over
the eastern mountains and I-25 corridor this afternoon, though
coverage of precip has remained rather sparse so far. Given LAPS
CAPES of 400-800 J/KG along and west of I-25, will keep some low
pops going until sunset, before activity wanes with loss of heating.
Suspect convection will have a difficult time pushing much east of
the I-25 corridor as instability is minimal over much of the plains.
Overnight, dynamic lift increases along the Continental Divide after
06z, with snowfall ramping up in coverage/intensity over the central
mountains by 12z. Will keep winter wx advisory in place for the
higher peaks north of Monarch Pass, as a few inches of accumulation
looks likely by sunrise. On Thursday, precip chances spread eastward
across most of the region, though best lift with the upper wave will
be over the northern half of Colorado. Will keep at least isolated
pops for showers at most locations through the day, with a slight
chance of a thunderstorm in the afternoon as weak instability
develops once again. With a little better mixing and a slight upturn
in mid level temps, maxes Thu afternoon should rise 5-10f over the
plains, while higher terrain sees little change.

.LONG TERM...(Thursday night through Wednesday)
Issued at 337 PM MDT Wed Apr 26 2017

...Potential for a High Impact Storm System across Southern Colorado
Friday night and Saturday...

Thursday night...Northwest flow moderates across the area as
embedded short wave translates across the northern Rockies Thursday
afternoon and continues into the Northern High Plains Thursday
night. Showers and a few embedded thunderstorms will be possible
across area Thursday evening, best coverage along and north of the
Palmer Dvd, with showers diminishing into Thursday night.  Still could
see pockets of freezing temperatures across the higher along and
west of the I-25 corridor though its still not clear how widespread
this will be given that westerly winds may help to keep temperatures
up a bit.

Friday-Saturday...Strong storm system still progged to develop as
strong jet core digs across the West Coast and into the Great Basin
during the day Friday and closes off an upper low across the Four
Corners Friday night. 12Z runs of the GFS and ECMWF still remain on
track to bring a high impact heavy rain and snow event to much of
southern Colorado, as they take the low across northern New Mexico
through the day Saturday and into the Oklahoma Panhandle Saturday
night. This track is very favorable for heavy rain and snow
across all of eastern mountains and southeast plains, with snow
down across all of the southeast plains by Saturday morning with
H7 temps progged between -6C and -10C.

The track of this system, however, remains in question, as the NAM
and Canadian runs, as well as some members of the GFS ensemble,
close the low off across the Four Corners Friday night, though dig
the system south into south central New Mexico Saturday before
lifting the system into western Texas Saturday night. These solutions
would still bring an initial surge of uvv and upglide to the eastern
mountains with east to northeast H7 winds of 30-40 kts Friday night,
though the best precipitation would slide south and east across the
Southern Sangre`s and Raton Mesa region as strong northerly winds
shuts down precipitation across northern portions of the area.

Although it still remains too early to nail down exact snowfall
amounts, this system still looks to be a high impact event across
the area, especially the southeast mountains and southern I-25
corridor, where significant snow accumulations will be possible
later Friday night and through the day Saturday. Snow would be wet
and heavy and could cause tree and powerline damage. The biggest
bust potential remains across the Pikes Peak region where snow
amounts will depend on track of the system, though. again significant
amounts of snow will be possible. Impacts across the southeast
plains will also be determined by the track of the system and the
timing of the switch over to snow and snowfall rates as the ground
is carrying some residual heat. Still not enough confidence to go
out with winter weather highlights, though will likely need some
soon, especially for the Southeastern Mountains.

Saturday night-Wednesday...The system pulls away Saturday night
leaving a cold airmass in place and the the potential for a
hard/killing freeze across all of south central and southeast
Colorado Sunday morning. A slow warming trend remains progged across
the area within a moderate west to northwest flow regime Sunday and
Monday, with another embedded wave moving across the area Tuesday
and Wednesday.


.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 337 PM MDT Wed Apr 26 2017

VFR at all taf sites the next 24 hrs. Isolated -shra will be
possible at KPUB and KCOS late this afternoon and into this evening,
and will include a vcsh mention in both terminals through 00z-02z.
Overnight, -shra chances diminish over the eastern mountains and
plains while mountains and interior valleys see increasing coverage
of -shra/-shsn, especially after 06z. Will include a vcsh mention at
KALS, with heavier precip obscuring the higher peaks along the
continental divide by morning. On Thursday, expect isolated to
scattered showers to persist across the area, with the potential for
a few weak -tsra after 18z. Most lower elevations will remain VFR
through the day, with mountains occasionally obscured by


Winter Weather Advisory from 6 PM this evening to 6 PM MDT
Thursday for COZ058-060.



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