Area Forecast Discussion
Issued by NWS Grand Junction, CO

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000
FXUS65 KGJT 191837
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
1137 AM MST Thu Jan 19 2017

.UPDATE...
Issued at 1137 AM MST Thu Jan 19 2017

Updated to remove expired Dense Fog Advisory headlines.

UPDATE Issued at 635 AM MST Thu Jan 19 2017

Issued a Dense Fog Advisory for the Animas and San Juan River
Basins, Colorado zones 22 and 23, which includes Durango and
Pagosa Springs valleys through 11 am MST this morning.
Visibilities at Durango have dropped to quarter mile within the
last hour with Pagosa Springs visibility lowering to half mile.
With nearly calm to light winds, do not expect much mixing through
the morning hours. The leading edge of cloud cover associated with
the next storm system approaching from the west is already edging
into eastern Utah. Expect these clouds to increase over Durango
and Pagosa by late morning and early afternoon, which should help
mix out the fog.

&&

.SHORT TERM...(Today through Friday)
Issued at 349 AM MST Thu Jan 19 2017

The current infrared satellite image is showing cold cloud tops
associated with an approaching storm system making their way
across Nevada and Utah. Mesoscale analysis suggests that these
clouds and associated boundary will reach western portions of the
CWA by around 6:00 AM MST this morning. A rain snow mix should
begin in Grand Junction by late morning early afternoon. Snow will
begin over the higher elevations by late morning early afternoon.

Snow accumulations are anticipated to become a travel concern this
evening into the overnight hours. Therefore, Winter Weather
Advisories and Winter Storm Warnings are in place and become
effective this afternoon remaining in effect through Saturday
evening. For more details see the Winter Storm messages on our
website or DENWSWGJT. Overall forecast confidence remains high
across the forecast area with the exception of Elk Head and Park
Mountain Zone, which remains in a Winter Storm Watch. This
particular area typically does not accumulate snow well in
southwest flow but the prolonged nature of this event may still
result in significant storm total snow fall.

.LONG TERM...(Friday night through Wednesday)
Issued at 349 AM MST Thu Jan 19 2017

The current satellite water vapor image is showing a low pressure
system centered in the Great Plains this morning. A trough of low
pressure is also digging into the west coast with a plume of
moisture evident over Nevada and Utah as an associated boundary
races towards our western CWA. The 0000Z ECMWF and 0600Z GFS20
have initialized well with these synoptic scale weather features
and remain in exceptional agreement through at least next Tuesday.

Both models indicate that the second of three weather disturbances
will begin to impact the forecast area early Saturday morning
providing additional snow accumulation across the CWA through
Saturday night. This portion of the storm system will be colder
than Thursday`s storm system and we are now expecting up to 2
inches of snow fall to accumulate in the Grand Valley Saturday
night. Moderate to heavy snowfall is also anticipated for the
mountains.

A break in the action is expected on Sunday as a ridge of high
pressure briefly builds over the Intermountain West. However, this
break will be short lived as the third and strongest segment of
the storm system sweeps into the area Sunday evening. This
segment is expected to have upper level jet support which will
promote higher snowfall rates across Eastern Utah and Western
Colorado through Tuesday evening. Overall forecast confidence is
high. Please be sure to be prepared for this prolonged period of
winter weather, have a plan, have some additional supplies in your
home and if you plan on travelling please check the forecast for
updates and consult UDOT and CDOT web pages for the latest road
conditions.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1137 AM MST Thu Jan 19 2017

Some low stratus remains at KDRO and KEGE through the early
afternoon. Clouds and light precipitation will increase this
afternoon across the area ahead of the next storm system.
Precipitation at lower elevation TAF sites will be a rain/snow mix
this afternoon before changing over to snow this evening.
Mountains will become obscured with snowfall becoming moderate to
heavy at times overnight through Friday afternoon. Deteriorating
conditions will be seen at the forecast terminals throughout the
day with lowering ceilings and visibility in showers.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...
CO...Winter Weather Advisory until midnight MST Saturday night for
     COZ003.

     Winter Storm Warning from 5 PM this afternoon to 6 AM MST Sunday
     for COZ009-010-012-013.

     Winter Storm Warning from 5 PM this afternoon to midnight MST
     Saturday night for COZ017-018.

     Winter Storm Warning until 8 PM MST Saturday for COZ019.

     Winter Storm Watch from 5 PM MST this afternoon through late
     Saturday night for COZ004.

     Winter Storm Warning from 8 PM this evening to 5 PM MST Saturday
     for COZ021>023.

UT...Winter Weather Advisory until midnight MST Saturday night for
     UTZ025.

     Winter Storm Warning until 5 PM MST Saturday for UTZ022.

     Winter Weather Advisory until 5 PM MST Saturday for UTZ028.

&&

$$

UPDATE...MDA
SHORT TERM...Larry
LONG TERM...Larry
AVIATION...MDA



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