Area Forecast Discussion
Issued by NWS Grand Junction, CO

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000
FXUS65 KGJT 191105
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
405 AM MST Sun Feb 19 2017

.SHORT TERM...(Today through Monday)
Issued at 403 AM MST Sun Feb 19 2017

Upper level low has lifted into Central Arizona early this
morning and will continue drifting northeast this morning into
the Four Corners Region where best pressure falls continue. The
low will continue to travel northeast in central Colorado by this
afternoon as it fills and phases with northern stream energy. Deep
southerly and somewhat difluent flow will drive moisture
northward with showers expanding in areal coverage throughout the
day as we see deeper moisture move in and infiltrate drier mid
layers. By this afternoon, models kicking out modest cape with
lapse rates steepening, which should be enough to kick off a few
afternoon thunderstorms. With convection in the forecast, would
expect areas of heavy rain/snow with lightning impacting outdoor
activities, especially for the backcountry enthusiasts. Snow
levels will vary as convection could drive levels down several
hundred feet as it moves through, but best accumulating snowfall
will still be at or above 9k for the most part. Current winter
highlights remain on track and no expansion in coverage needed
based on new QPF/Snow amounts in latest forecast.

This storm continues to impact the area through this evening,
before we start to see improving conditions from southwest to
northeast late tonight. Snow showers are expected to linger over
the northern and central mountains through sunrise Monday morning,
before completely shutting down by midday Monday as shortwave
ridging slides overhead.

Overall warm nature to this system will limit most significant
impacts to the nocturnal hours, when temps will be the lowest,
allowing slush, ice and snow packed conditions to develop on the
higher mountain highways.

.LONG TERM...(Monday night through Saturday)
Issued at 403 AM MST Sun Feb 19 2017

An upper level ridge axis over the area will be dampened and
suppressed southward Monday night as the next upper level trough
approaches the West Coast. Upper level southwesterly flow
increases over eastern UT and western CO during the day Tuesday as
a strong upper level jet crossing California begins to nose
eastward. Moisture being brought along from the central Pacific
will start getting into our area Tuesday night and result in
mainly orographically oriented precipitation. A more well-defined
upper level trough will push through Thursday morning along with a
bonafide cold front as a strong lee surface cyclone develops over
eastern CO. The Wednesday night and Thursday time period look to
be the time with greatest and most widespread precipitation
potential during the coming week with strong dynamics and
frontogenetical forcing in play. Winter weather highlights
certainly possible at least for the mountains and higher
valleys/plateaus. In addition, there is good agreement with a
pattern change to a mean trough over the intermountain West and
cooling trend for the latter half of the week which will likely
extend through the weekend and may be cooler than currently
forecast.

&&

.AVIATION...(For the 12Z TAFS through 12Z Monday morning)
Issued at 403 AM MST Sun Feb 19 2017

Low clouds, fog and light showers will continue to impact the
valleys of eastern Utah this morning with showers spreading across
western Colorado through the day. Expect ILS cigs to becoming
common across western Colorado this morning with areas of MVFR and
eventually IFR conditions spreading from southwest to northeast
across the region as an upper level low pressure system lifts out
of Arizona. Mountains will be frequently obscured through the
period as showers increase in coverage. After 19Z this afternoon,
expect isolated thunderstorms, mainly south of Interstate 70.
Conditions improved from southwest to northeast after 04Z/MON.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...
CO...Winter Weather Advisory from 11 AM this morning to 7 AM MST
     Monday for COZ009-010-012-013.

     Winter Weather Advisory until 6 PM MST this evening for COZ018-
     019.

UT...Winter Weather Advisory until 6 PM MST this evening for UTZ028.

&&

$$

SHORT TERM...JDC
LONG TERM...BM
AVIATION...JDC



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