Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 141126

Area Forecast Discussion
National Weather Service GRAND JUNCTION CO
426 AM MST Thu Dec 14 2017

.SHORT TERM...(Today through Friday)
Issued at 226 AM MST Thu Dec 14 2017

The shortwave trough continued to sweep southeastward across
eastern Utah and western Colorado early this morning and the cold
front associated with this system had exited to the south.
Snowfall associated with this system extended from the lower
elevations of northwest Colorado across Colorado`s mountains
according to automated sensors, radar, and web cams as of 3 AM
MST. However, northern and central mountain ski area snow stakes
showed very light snow accumulations so far of just an inch or
less. Meanwhile, subsidence on the backside of the trough has
brought clearing to the eastern Uinta Basin and snow has ended at
KDWX, KCAG and KEEO and was decreasing at KHDN and KSBS.

Expect improving conditions to work southeastward across the
region during the morning as the trough axis shifts south of the
area later this morning. Snow rates should remain unimpressive and
therefore do not anticipate significant impacts from snow over the
higher passes early today. Snow will end before noon for most
locations but may linger in the southeast San Juans a bit longer.
Temperatures will be cooler in the mountains with less pronounced
changes across the valleys this afternoon. In fact, cold frontal
passage will cause some previously inverted valleys to become a
bit warmer today which is a bit counterintuitive, though increased
sunshine will also help.

Dry northerly flow aloft will result in clear skies and cold
overnight lows tonight. Single digits and teens will be the norm
for much of the area. Midslopes and portions of southeast Utah
will be a bit milder with lows in the lower to mid 20s. Flow aloft
backs to the northwest Friday ahead of the next Pacific trough.
Atmospheric moisture remains low so dry weather will continue,
though clouds will be increasing from the northwest later in the
day ahead of the previously mentioned trough. Temperatures will
moderate in the mountains with little change expected in the
unseasonably mild valleys.

.LONG TERM...(Friday night through Wednesday)
Issued at 226 AM MST Thu Dec 14 2017

The axis of the upper level ridge will begin to be flattened
Friday night and into early Saturday as the next shortwave trough
drops into the northern Great Basin. Mid and high level clouds
will increase ahead of this system with isolated to scattered high
based showers developing as early as Saturday afternoon, though
differences in the arrival and track of this system vary between
models. Either way, this will be a quick moving storm and is only
expected to produce another round of light snow for the mountains
as it moves across our area into Sunday.

Weak transitory ridging looks to return to the region early next
week, allowing skies to mostly clear and temperatures to
moderate through about the mid week point. Model solutions really
begin to diverge from this point onwards in regards to the
progression of the next Pacific storm. The GFS handles this storm
as a longwave trough, digging into the western CONUS throughout
the latter half of next week. The Euro on the other hand is
considerably slower and doesn`t introduce the system onshore until
late Thursday/Friday, so confidence in the long term remains low
at this point. On the bright side, we have transitioned to a more
progressive weather pattern going into the second half of December
which tends to promise some periods of active weather!


.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
Issued at 426 AM MST Thu Dec 14 2017

Light snow and low clouds will result in brief IFR visibility at
KEGE and KASE through 14Z. Expect CIGS below ILS breakpoints at
these sites and KGUC through the latter part of the morning.
Otherwise, VFR conditions will prevail across the area during the
early part of the day. All TAF sites will enjoy VFR conditions
from midday through tonight.






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