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Area forecast discussion 
National Weather Service Grand Junction Colorado
402 am MST sun Feb 1 2015

Short term...(today through monday)
issued at 402 am MST sun Feb 1 2015

Some low clouds and fog persist early this morning in some of the
valley areas. The clouds/fog seems to be somewhat spotty...but dense
fog has been reported at a couple sites in the south...kdro and
for awhile at kbdg. Expect that dense fog is possible at other
locations as well. Will let the dense fog advisory ride for
portions of southeast Utah and southwest Colorado through the morning. And
at 330am MST...the satellite fog product indicated that the low
clouds were expanding into the grand flats in east cental
Utah...with kcny down to 1/2 mile. So will expand the dense fog
advisory to include this area.

As the southern low pressure system continues to drop into western
Mexico...a northwest flow has developed over the region. This flow
will dominate through midweek and beyond as a series of waves
embedded in the flow brush our northern forecast area. The first
wave to pass stayed east of our forecast area last night...and has
already been exiting eastern Colorado early this morning. For our
County Warning will be the 'in-between' day with the next wave
approaching this evening. This wave will pass late tonight into
Monday and will bring snow to the northwest Colorado mountains. The best
snowfall is expected from around 3am MST to midday Monday as an
approximate 80kt upper level jet core noses into northwest
Colorado...not overly strong. The park...Elkhead and Flattops will be
favored...helped by the northwest orographic flow. This wave will
begin a rather prolonged period of snowfall for the northern
mountains...with lulls at times. While eventually we could see
significant snowfall not expect more than a few
inches with this first wave.

Long term...(monday night through saturday)
issued at 402 am MST sun Feb 1 2015

Models indicated a brief lull in snowfall over the northern
mountains Monday evening as the polar jet shifts east over the
plains. However...the break will be short lived as the next in a
series of disturbances moves over the north early Tuesday. This
regime of moist northwest flow and embedded disturbances indicated
to persist through Wednesday or Wednesday night depending upon the
model. GFS and NAM indicated the potential for significant snow
accumulations over the Elkhead...park...and Flat Top mountains
during this prolonged event. However...snowfall generated by the
European model (ecmwf) less impressive. As a result...will hold off on a watch for
the northern Colorado ranges until better agreement is reached.

Ridge builds over the west later in the week resulting in drying
across the north bringing an end to snowfall. Next chance for
snow comes Friday night into Saturday as a landfalling trough
breaks down the ridge.

Mild winter temperatures will warm further later this week with
highs rising to near 15 degrees above normal by weeks end.


Aviation...(for the 12z tafs through 12z Monday morning)
issued at 402 am MST sun Feb 1 2015

Low stratus and fog will persist this morning in a cold...
saturated airmass across southeast Utah and southwest Colorado. As
a result...expect IFR/LIFR ceilings/visibility at many of the southern most
airports within the forecast area...including kdro...until 17z.
Similar conditions are also possible in the central valleys and
may briefly impact kgjt and kcny in particular.

Expect VFR conditions to prevail from 18z through 00z/Monday as a
drier northwest flow settles over the region. However...expect
snow to develop over the northern Colorado mountains from 00z to
06z/Sunday Sunday with the arrival of a weak disturbance. Snow
increases over the northern mountains later tonight resulting in
widespread mountain obscuration. Snow becomes likely during this
time period for the lower elevations of the northwest plateau east
of a kcag to keeo line. However...taf sites will continue to
experience VFR conditions tonight.


Gjt watches/warnings/advisories...

Colorado...dense fog advisory until 10 am MST this morning for coz021>023.

Utah...dense fog advisory until 10 am MST this morning for utz022-027-



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