Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 241134

Area Forecast Discussion
National Weather Service Grand Junction CO
434 AM MST Tue Jan 24 2017

.SHORT TERM...(Today through Wednesday)
Issued at 354 AM MST Tue Jan 24 2017

The forecast area experienced a lull in snowfall overnight as
satellite showed the occluding center of the storm over central
Wyoming as of 10Z and its associated cold front east of the
Continental Divide. The airmass in the wake of the front was
considerably drier with 7H specific humidity ranging from 2 g/kg
in the north to near 2.5 g/kg in the south. Given the lack of
large scale lift and drying, the lull is understandable.

However, satellite also showed a shortwave trough rotating through
northeast Arizona which, when combined with a tropospheric fold
east-west across the lower elevations of southwest Colorado should
cause snow to redevelop. Surface observations from northeast
Arizona and northwest New Mexico seemed to bear this out. Both NAM
and GFS indicated snow will continue through noon so extended
warning for CO zones 21 through 23, though only an additional 1 to
3 inches expected. Meanwhile, in the mountains the combination of
steep lapse rates and orographic lift provided by west to
northwest winds is expected to continue to bring snow to the
high country. Therefore, will keep highlights going across the
mountains of western Colorado through the day.

Wrap-around moisture from the upper-level low will continue to
feed showers over the northern mountains through Wednesday, while
snow showers become more scattered over the southern mountains by
sunset. Therefore, will allow WSW`s over the southern mountains
expire at the end of the day, but will continue highlights across
the north through Wednesday.

In the wake of the cold front temperatures will be below normal
through midweek.

.LONG TERM...(Wednesday night through Monday)
Issued at 354 AM MST Tue Jan 24 2017

Additional upper level energy drops south from Canada during the
middle of the week, maintaining a general north to northwesterly
flow over the region and colder than normal temperatures. Moisture
will continue to ride upslope over northern CO Wednesday through
Thursday, though with increasingly lower amounts. Snow showers
will decrease in coverage Thursday. Models agree on a long wave
ridge amplifying over the West Coast late in the week blocking any
moisture from entering the Central Rockies. Should be a dry
weekend with seasonal to possibly below normal temperatures.


.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)
Issued at 434 AM MST Tue Jan 24 2017

Numerous snow showers are expected over the mountains through the
next 24 hours resulting in widespread obscuration of peaks and
ridges. A disturbance moving across the Four Corners region is
expected to keep KTEX and KDRO below ILS breakpoints with MVFR
VSBY and periods where CIGS are in the IFR range. Meanwhile, fog
has descended on KVEL and expect IFR CIGS and VSBY will continue
there through 16-17Z before transitioning through MVFR to VFR
early in the afternoon. KASE has a chance for showers prior to
18Z, but as flow increases from the northwest expect the Roaring
Fork Valley will become socked in with snow through the remainder
of the afternoon with low CIGS persisting during the night. The
remaining TAF sites face a low end chance for snow showers,
especially this afternoon, though any impact to airport operations
should be short in duration.



CO...Winter Storm Warning until 9 AM MST Wednesday for COZ012.

     Winter Storm Warning until 6 PM MST this evening for COZ009-018-

     Winter Storm Warning until 9 AM MST this morning for COZ017.

     Winter Weather Advisory until 9 AM MST Wednesday for COZ010.

     Winter Storm Warning until 6 PM MST Wednesday for COZ004-013.

     Winter Weather Advisory until 6 PM MST this evening for COZ003.

     Winter Storm Warning until noon MST today for COZ021>023.




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