Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 170536

Area Forecast Discussion
National Weather Service Grand Junction CO
1036 PM MST Sun Feb 16 2020

.SHORT TERM...(Tonight through Monday night)
Issued at 238 PM MST Sun Feb 16 2020

Moderate to heavy snow showers continue this afternoon across the
northern and central Colorado mountains with light showers just
recently having developed over the San Juan Mountains. As
expected, impressive warm air advection as a result of the ongoing
Atmospheric River has led to mild temperatures this afternoon
with many of the lower valleys sitting in the mid to upper 40s and
low 50s. These above seasonal readings are not just confined to
the lower elevations with areas such as Telluride sitting at 39
degrees. Given these mild temperatures, impacts have been confined
to the northwest and west-central Colorado mountains where
SNOTELs estimate up to 10 inches of snow has already fallen thus
far with snow ratios sitting at 13:1 or less. The evening and
overnight hours will see a midlevel trough and associated cold
front progress through the region with much colder air being
ushered into the area in its wake early Monday morning. 700mb
temperatures will drop from -4 to -8 degrees C north of I-70
to -8 to -14 degrees C by daybreak Monday. South of I-70, today`s
700mb temperatures of 0 to -4 degrees C will cool to -4 to -8
degrees C. Given these much cooler temperatures, snow ratios will
rise and, when paired with favorable jet dynamics aloft and
orographics, will allow the northwest and west-central Colorado
mountains to see a very efficient 6 hours or so of snow. Snow
rates could exceed 1 to 2 inches per hour at times which, when
paired with wind gusts nearing 50 MPH, will result in hazardous
travel during the overnight period. Therefore, the ongoing winter
highlights remain on track with this afternoon`s package. Monday
morning will see the cold front and upper level jet progress to
the southeast with drier air advecting into the region in its
wake. As a result, snow showers will taper off in both intensity
and coverage. However, residual moisture will be enough to fuel
isolated to scattered orographic showers along the Divide
throughout the day, though additional accumulations look to remain
below highlight criteria. Daytime highs, though cooler than
Sunday, will still be above the seasonal norm. An exception will
be across far northwest Colorado and northeast Utah where readings
will sit 3 to 6 degrees below normal.

Another weak cold front will drop south from Wyoming Monday night
and into early Tuesday. This feature will briefly enhance snow
showers along the Divide, most notably across the West Elk and
Sawatch Ranges in west-central Colorado. Again, snowfall looks to
remain below advisory criteria with generally 2 to 4 inches
expected. Elsewhere, expect partly to mostly cloudy skies with
near to below normal overnight lows.

.LONG TERM...(Tuesday through Sunday)
Issued at 238 PM MST Sun Feb 16 2020

Showers along the Continental Divide will come to an end Tuesday
morning as zonal flow sets up overhead. The synoptic forecast
remains messy for Wednesday and early Thursday as a piece of
energy along the west side of a broad trough situated over the
central CONUS splits off and progresses towards the Desert
Southwest. As has been the trend over the last several model runs,
this feature will remain weak with any impacts confined to far
southwest Colorado. Snow accumulations continue to look
unimpressive. The remainder of the forecast area, particularly
centered near the Four Corners, will see continued mostly to
partly cloudy skies. Any showers look to diminish by Thursday
evening with a weak transitory ridge setting up overhead for
Friday and into early Saturday. After that, a Pacific low sets its
sights on southern California with a projected onshore arrival
date of Saturday evening. Extended models favor a continued closed
low as it drifts inland across Arizona Saturday night and into
Sunday. However, as is the norm this far out, discrepancies exist
in the overall track, intensity and progressive nature of the
storm and these details will become more clear over the coming
days. Regardless, the overall active weather pattern holds steady
through the long term period.

Temperatures will be on the rise through the extended forecast as
700mb temperatures rebound with the shift of flow aloft. The end
of the week and into the weekend will see the biggest jump as
upper level flow shifts to the southwest ahead of the next Pacific


.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1030 PM MST Sun Feb 16 2020

Snow continues for KGUC, KSBS, and KHDN at this hour and will
likely continue through the early morning hours. Ceilings at KASE,
KEGE and KRIL remain around 8K feet but expect them to drop in a
few hours as snow moves in again. By 12Z, snow will become more
light in nature allowing visibilities and ceilings to lift. By
18Z, conditions will improve greatly across the forecast area as
snow comes to an end and broken ceilings move in. Another quick
shot of snow may move in towards the end of the TAF period but
should only affect KHDN though there`s an offchance that KEGE and
KASE may see some lower ceilings as well.


CO...Winter Weather Advisory until 8 AM MST Monday for COZ005-010-012.

     Winter Storm Warning until 8 AM MST Monday for COZ004-013.



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