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Area forecast discussion
National Weather Service Denver/Boulder Colorado
820 PM MST Wed Jan 18 2017

issued at 803 PM MST Wed Jan 18 2017

No significant adjustments to the forecast this evening. Overall a
dry and stable airmass will remain in place overnight with a weak
northerly flow aloft over Colorado, with a ridge axis over western
Colorado and a weak closed low over western Kansas. Not much evident on
water vapor this evening with just some high level moisture over
east central/sern Colorado. The main plume of moisture is still well to
the west over NV, making its way into western Utah at this time. The
upper level ridge axis will continue over western Colorado through 12z
Thu then move over eastern Colorado by 00z Friday. This area of lift
associated with the next storm system is still not expected to
reach the cwa until Thu night/Friday morning.


Short term...(this evening through thursday)
issued at 255 PM MST Wed Jan 18 2017

A weak upper level circulation is slowly tracking over western
Kansas this afternoon, rotating some high level clouds back over
eastern Colorado. Otherwise, a dry airmass will remain in place
over north central and northeast Colorado overnight just the
northeast Colorado plains tomorrow. Over the mountains tomorrow,
moisture will be increasing from the west as a negatively tilted
trough digs over the Great Basin. Model cross sections show the
moisture deepening enough to begin producing snowfall by late
tomorrow afternoon. As the flow at lower and mid levels is
forecast to be southwesterly, the San Juan Mountains will be the
part of the state to receive the best snow fall. Anything the
northern mountains receive will be after 5 PM tomorrow afternoon.
Temperatures will be around seasonal normals overnight and then a
little warmer than normal tomorrow afternoon.

Long term...(thursday night through wednesday)
issued at 255 PM MST Wed Jan 18 2017

There is an active weather pattern for the long term with snow
returning to the mountains and a chance for the plains.

For Thursday night into Friday moisture will increase across
western Colorado due to the incoming trough over Nevada. A surface
low will help to keep the plains dry through Friday morning. With
the increased moisture combined with qg lift there will be a
chance of snow for the mountains with a slight chance of a rain
and snow mixture for the plains by Friday evening as the low drops
south and qg kicks out to the NE over the plains. Temperatures for
Friday into the weekend will be hovering around normal with highs
in the 40s and lows in the teens and 20s. Subsidence will
increase behind the trough with upper level winds turn westerly.
This will rebuild the surface low drying out conditions on
Saturday. Kept a slight chance of snow in the mountains with
lingering moisture. The next upper level feature will stay south
of the state keeping the main branch of energy over nm and the
Texas Panhandle. There is a continued chance of snow in the
mountains while staying dry on the plains. Conditions will
stabilize through Sunday with a ridge building in decreasing snow
across the mountains.

The next weather maker will move into the region starting next
week. The models diverge after the latest 12z run with the ec
coming more in line with the Canadian. They have an upper wave
over the state on Monday followed by a ridge and then
another...deeper closed low moving over the state Tuesday night.
The GFS however has a deep low entering the state on Monday night
with the low center over the eastern border of Colorado and Kansas that
could bring accumulating snow to the plains by Tuesday. Both
solutions will being accumulating snow to the mountains but will
have to continue to monitor to see exact timing and amounts for
snowfall on the plains. Models do indicate a cold front dropping
down by Tuesday morning that would usher in cooler temperatures
and help to turn any rain into snow for the plains. This will
bring high temperatures from the 40s on Monday into the upper 20s
to lower 30s by Wednesday.


Aviation...(for the 06z tafs through 06z Thursday night)
issued at 803 PM MST Wed Jan 18 2017

No aviation impacts expected through 06z Thu night. Mostly clear
skies overnight and Thursday along with unrestricted visibilities.
Winds will be light and southerly overnight and then more
variable through Thu. Increasing high level cloudiness developing
Thu evening ahead of the nxt approaching Pacific storm system
which should impact northeast Colorado late Thu night and Friday.


Bou watches/warnings/advisories...


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