Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 201513
AFDGJT

Area Forecast Discussion
National Weather Service GRAND JUNCTION CO
813 AM MST Tue Feb 20 2018

.UPDATE...
Issued at 813 AM MST Tue Feb 20 2018

Some light and narrow bands of snow linger over west-central
Colorado this morning. This has resulted in some periods of
reduced visibility in areas such as Aspen and Montrose. These
light showers will continue over the next couple of hours but
accumulations will be minimal. Therefore the remaining winter
weather highlights were allowed to expire at 8 AM. However, roads
will still be slick and snow-packed during the morning commute so
please use caution while driving and check the latest road
conditions before heading out by visiting the respective DOT
website or by calling 511.

&&

.SHORT TERM...(Today through Wednesday)
Issued at 356 AM MST Tue Feb 20 2018

Been able to shave off some of the winter highlights as winds and
heavy snow threat has been diminishing with the jet and large
scale ascent shifting northeast. However plenty of other meso-
scale features keeping snow going over the area. Up north seeder
feeder seems to be keeping light snow going. EPV in a fairly
distinct lapse rate gradient is keeping some decent convective
bands coming off the UnCo into the Olathe to Montrose region and
may have a sunrise surprise there...travel definitely impacted
along Hwy 50 at times. This also probably associated with the mid
level front pushing through. Much of the southern mountains have
shut off except for some isolated showers. Cold air continues to
spill in overhead as the main trough swings through which means
convective bands of snow continue through the day. Mainly centered
on the terrain but some of the showers are likely to drift into
the valleys at times. Where? Yes. Much cooler today though less
breezy. Clearing and cold tonight as we get a short break between
the next system. New snow cover and drier air will mean some spots
will really be dropping off and could be the coldest reading of
the winter in some spots up north. Wednesday with the cold start
and cold air in place still cooler than normal temperatures stay
in place. This will set the stage for another snow event as the
next trough digs to or west and pushes moisture and southerly flow
into the Colorado mountains late in the day. More on that below.

.LONG TERM...(Wednesday night through Monday)
Issued at 356 AM MST Tue Feb 20 2018

The long term period will be dominated by a long wave trough that is
carved out over the western states, centered over the Great Basin.
Temperatures through Sunday will remain quite cool as H7 temps
throughout the period remain within the -10C to -14C range from
south to north respectively. Southwest flow will dominate through
Friday, with some showers possible over mainly the higher terrain
Wednesday night into Thursday with a weak shortwave ahead of the
main upper level trough. Not expecting too significant of
precipitation with these showers as QPF amounts remain fairly light.
This is similar in design to a warm advective regime, without the
warm air.  The main upper level trough will kick out of the Great
Basin and move through the area Friday into Saturday morning,
bringing another round of snowfall. Breezy to windy conditions are
anticipated across the area Thursday night into Friday afternoon
ahead of this system, which looks fairly convective once again as we
head into the Spring months. The pattern remains progressive as
another trough will move through in northwest flow Sunday into
Monday morning. Temperatures look to moderate heading into the
coming week with a return to above normal temps as a ridge tries to
move in and influence our weather beyond this coming weekend. Models
seem to be in fairly good agreement overall on the timing of these
systems but differences as always lie in the fine details.
Regardless, this progressive active pattern looks promising for more
snowfall across the mountains continuing what has been a snowy
February.

&&

.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)
Issued at 356 AM MST Tue Feb 20 2018

Expect conditions to slowly improve today as the main part of this
storm has shifted east. However unstable air means showery
precipitation and this could again quickly drop VFR to LIFR as
snow moves through. This most probably in the KASE and KTEX areas
but can not rule this out of most of the western Colorado TAF
sites. Winds could gusts near the showers but overall wind
conditions will be much improved over yesterday. Overnight much
colder and clear conditions move in which could lead to some fog
issues but this airmass is quite dry so confidence very low on
timing and locations.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...
CO...None.
UT...None.
&&

$$

UPDATE...MMS
SHORT TERM...15
LONG TERM...MDA
AVIATION...TGJT



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