Area Forecast Discussion
Issued by NWS Pueblo, CO

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FXUS65 KPUB 172032

Area Forecast Discussion
National Weather Service Pueblo CO
232 PM MDT Thu Aug 17 2017

.SHORT TERM...(This evening through Friday)
Issued at 231 PM MDT Thu Aug 17 2017

This evening, a weather disturbance will be moving acrs western NE
and also affecting portions of eastern CO.  A limited amount of
showers/tstms are expected this evening, with the majority of the
activity expected to be over the central and eastern mountains, and
over the southeast plains. It still looks like the most favorable
area for potential severe weather will be over the far southeast
plains.  The current meso analysis indicates 2000+ J/kg of CAPE over
the far southeast plains, and deep layer shear values of around
40kts. Much of the convective activity is forecast to be done by 02-
03Z, but both the NAM and the HRRR show lingering pcpn into the late
night hours over the far southeast corner, so I will keep some isold
pops in that location past midnight.

Behind that weather disturbance, a front is expected to move into
southeast CO Fri morning bringing northerly winds, that then become
easterly in the afternoon.  The forecast models show very limited
amount of convection, with maybe just some isold showers/tstms
developing over the mtns.  High temps on Fri should be around

.LONG TERM...(Friday night through Thursday)
Issued at 231 PM MDT Thu Aug 17 2017

Friday night`s weather should remain benign over much of the region,
with the GFS20 hinting at a few mountain showers during the early
and later afternoon hours. The NAM also hints at mountain storms, as
well, but not nearly as widespread as the GFS20. The plains should
remain clear form any convection Friday evening, low dew points
temperatures accompanied with a solid cap will inhibit any storms
from developing.

A lee trough will develop over the region on Saturday. That lee
trough will interact with a CAPE values ranging from 1000 - 1500
J/kg over the far eastern plains. The thunderstorms will be likely
be short-lived due to the lack of shear in the atmosphere. Potential
risks include strong thunderstorm winds and small hail. The NAM12
and GFS20 also indicate some weak thunderstorms developing over the
Palmer Divide, Eastern San Juans, and the southern Wet Mountains.
There will be much less energy and shear in the atmosphere over
these regions, so the storm that develop will be short-lived and

Sunday - Thursday

The monsoonal moisture surge will return on Sunday, and the biggest
forecast question is where the location of the upper-low and upper-
ridge will set-up. The European model has the upper-low set-up over
north-central Utah and the ridge built more westerly, over Colorado,
whereas the GFS pinpoints the upper-level low off the coast of
California and the upper-level ridge over the central United States.
Nevertheless, the response will be daily thunderstorms initiating in
the early afternoon over the mountains and spreading over the plains
during the late afternoon to early evening hours, but the
uncertainly lies on where the low-level moisture will settle. Over
late Monday evening and early Tuesday morning, a weak cold front
will propagate over the region, bringing the possibility for
prolonged showers during the overnight hours. Post frontal moist
upslope flow will likely bring widespread cloud cover over most of
the region, so expect a few overcast days following Monday. The long
term GFS20 resolves a lee cyclone developing over northern Colorado
on Wednesday night and Thursday morning, and if that verifies,
expect wide spread precipitation as the low and its associated
fronts, pass the area.



.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 231 PM MDT Thu Aug 17 2017

VFR conditions are expected at KCOS, KPUB and KALS through the next
24 hrs.  This evening there will be the possibility of showers/tstms
at or near KCOS, and there is a small chance that showers/tstms
could move into the KPUB and KALS areas.   Precipitation chances
near the terminal forecast sites should mostly end by 02-03Z. On Fri
there may be some precipitation over some of the mtn areas, but at
this time it looks like they should not affect the terminal forecast




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