Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 090012

Area Forecast Discussion
National Weather Service Grand Junction CO
512 PM MST Thu Dec 8 2016

.SHORT TERM...(Tonight through Friday night)
Issued at 342 PM MST Thu Dec 8 2016

An active zonal flow pattern will continue over the region for
the next 7 to 10 days. Atmospheric moisture has begun to deepen
across the higher elevations of NW CO but will be become more
widespread and bring dewpoints up across all of eastern UT and
western CO throughout the next 24 hours. Snow is expected to
remain light across most of western CO this evening, but
accumulate about 5 to 8 inches from the Steamboat Springs mountain
area south to Vail Pass and the Maroon Bells with lesser amounts
at Aspen. Forecast models indicate this snowfall will lighten if
not stop completely by Friday afternoon.

.LONG TERM...(Saturday through Thursday)
Issued at 342 PM MST Thu Dec 8 2016

Strong warm air advection will be occurring with the moisture
increase over the next few days, with H7 temps increasing from
-15C (now) to around -1C by Saturday evening. This will make for
an interesting forecast period with snow levels changing and
dynamic processes occurring due to warm air overrunning. The one
thing we know for sure is that the setup beginning Saturday and
going through the weekend looks to dump a lot of moisture across
eastern UT and western CO. The forecast models today are bringing
the incoming weather system further south than previous runs which
impacts all of western Colorado overnight Saturday night into
Sunday morning. It`s looking at this time that snow level will be
around 6500 to 7000 ft, but I`m not feeling super confident on
this as these levels do seem high and we are dealing with a WAA
case during the overnight hours. During this late Saturday night
into Sunday time period the 120 kt upper level jet drapes
southward across UT and CO, which will further enhance the
orographic component to the snowfall in the mountains. Right now
the forecast models indicate a break by Sunday afternoon before an
additional system moves in on Tuesday bringing even more snow.
This pattern with snow makers every few days will continue, so
snow lovers rejoice, but travelers beware and be ready for winter
driving conditions.


.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 501 PM MST Thu Dec 8 2016

Moist northwesterly flow is in place over the western CONUS. This
moist northwesterly flow will support periods of snow overnight for
terminals in the vicinity of I-70 and northward. VFR conditions
are anticipated to degrade to MVFR overnight at a majority of the
terminals with the exception of terminals in Southeast Utah and
Southern Colorado. Generally light diurnal winds are anticipated
over the next 24 hours.

Overall forecast confidence is high.


CO...Winter Weather Advisory until 6 PM MST Friday for COZ004-010-013.



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