Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 120536
AFDGJT

Area Forecast Discussion
National Weather Service GRAND JUNCTION CO
1036 PM MST Thu Jan 11 2018

.SHORT TERM...(Tonight through Friday night)
Issued at 334 PM MST Thu Jan 11 2018

Modest moisture in northwest flow continued to bring scattered
light snow showers to portions of the Elkhead, Park and Gore
Ranges early this afternoon. Models indicated a downward trend in
coverage and intensity later this afternoon and early this
evening. However, a fast moving shortwave trough moving from the
Pacific northwest will sweep across northwest Colorado later
tonight into Friday morning causing snow to increase later this
evening. Orographic lift provided by favorable and brisk
northwest winds at the 7H level will combine with mid-level lift
and jet divergence to sustain snowfall from late evening through
Friday morning. Snow will continue, but decrease in intensity as
the dynamic forcing wanes and orographics becomes the primary
driver for continued snowfall Friday afternoon. Though moisture
not all that impressive at roughly 3 g/kg at the 7H level,
persistent snowfall is expected to bring 5 to 10 inches of new
snow to the Elkhead and Park Ranges and from 4 to 8 inches to the
Flat Tops, Gore and Elk Mountains by 6 PM Friday. Gust northwest
winds in the higher elevations ranging from 15 to 25 MPH with
gusts as high as 40 MPH at times is expected to bring blowing
snow as well. Therefore, have hoisted a Winter Weather Advisory
for snow and blowing snow for the areas mentioned previously.

Snow showers will impact portions of the Grand Mesa, West Elk,
Sawatch and western San Juan Mountains tonight and Friday, though
coverage will be more scattered in the central mountains and
isolated over the San Juans. West and south of the areas discussed
previously can expect dry weather with partly cloudy to mostly
clear skies. Moisture decreases Friday night as the ridge to the
west of the forecast area builds. As result, expect snow to
decrease during the night with flurries continuing over the
Elkhead and Park Mountains into Saturday morning.

As has been the case for much of the winter season, temperatures,
both afternoon highs and overnight lows will remain above normal.

.LONG TERM...(Saturday through Thursday)
Issued at 334 PM MST Thu Jan 11 2018

Models were consistent in depicting a prolonged period of dry and
unseasonably mild conditions through Tuesday night as high
pressure dominates the west. Models break down the ridge Tuesday
night into Wednesday. However, both GFS and Canadian solutions
favor a shallower low pressure system moving through the ridge
relative to the ECMWF leading to continued dry weather through
Wednesday. In contrast, the EC is colder and more energetic with
a system moving across northeast Utah and northwest Colorado late
Wednesday night into Thursday with a low closing off in the lee of
the Rockies over southeast Wyoming late Wednesday afternoon. This
system then slides south-southeastward Wednesday night. This
solution brings a chance for snow to the northern and central
Colorado mountains Wednesday into Thursday morning while GFS only
generates very modest QPF Wednesday night and the Canadian remains
dry. Given model differences, will continue with very low PoP
values for the middle to latter part of next week. Meanwhile,
warmer than normal temperatures will persist.

&&

.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1036 PM MST Thu Jan 11 2018

Moist northwest flow is spreading snow across the northern and
central Colorado mountains this evening with widespread terrain
obscuration. The lower cigs and precipitation is delayed at the
valleys with only some high ILS break points being met. Cigs look
to lower at KHDN...KEGE...and KASE through the early morning hours
with MVFR to IFR conditions being met through mid morning as the
main energy aloft passes through. Improving conditions then
expected through the afternoon hours though some higher peaks will
remain hidden in clouds.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...
CO...Winter Weather Advisory until 6 PM MST Friday for COZ004-010-013.

UT...None.
&&

$$

SHORT TERM...NL
LONG TERM...NL
AVIATION...TGJT



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