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Area forecast discussion 
National Weather Service Grand Junction Colorado
1105 PM MDT Monday Oct 12 2015

Short term...(this evening through Tuesday night)
issued at 311 PM MDT Monday Oct 12 2015

High pressure aloft will be anchored from New Mexico...over The
Four Corners to northern California through the short range. The
only challenge in this pattern is determining where overnight lows
will go below freezing in the valleys under the clear sky and calm
wind conditions. Last night the central Yampa River basin over
toward Steamboat...the central Colorado River Basin and Gunnison
Valley all had several locations at or below freezing. Tonight
should be a touch colder so have expanded the freeze warning to
include all 4 of these zones. The lower Yampa River basin of far
northwest Colorado and the zone containing Pagosa Springs will
flirt with freezing temperatures in isolated areas...but is not expected
to be widespread enough to include in freeze warning. Otherwise
abundant sunshine and a modifying airmass will result in a degree
or two of warming Tuesday.

Long term...(wednesday through monday)
issued at 311 PM MDT Monday Oct 12 2015

Wednesday and Thursday will be much like Tuesday. By late Thursday models in good agreement showing the cut off
upper level low over Southern California opening up and becoming absorbed
in the southwesterly flow developing ahead of an approaching
longwave trough from the northeast Pacific. Moisture begins to
creep into The Four Corners region late Thursday...but with dry
air in place it will take a while to realize showers. Shower
chances get better Friday over southwestern areas...then over the
rest of the area Friday night/Saturday with passage of this lows
remnants. Timing of cut off low movement is always tricky and
usually slower than models suggest in the longer range. So the
Friday/Sat timeframe I described above has already built in some
delay...but this delay in onset of precipitation may also need to be
lengthened in time.

Regardless...without much of a break...lift associated with the
longwave trough will begin impacting the region Sunday and
continue through Monday. This period could well end up being
wetter than Friday/Sat due to stronger forcing and the atmosphsere
moistened by the preceding shortwave. Isolated thunderstorms are
also possible through the weekend with some weak available
instability and dynamical forcing. The snow level will likely be
around 12kft Friday through Sunday...then as colder air moves in with
the longwave trough late Sunday...the snow level will drop to
around 9kft north to 10kft south. It is too early to determine
exact potential for rain and snowfall amounts...but we will
monitor forecast trends closely this week. This weather pattern
does have the potential to produce respectable rainfall for lower
elevations and eventually accumulating snow on the Popular
Mountain pass travel routes.

Overall...temperatures will be cooler over the weekend into next week
with cloud cover and arrival of cooler air from the north.


Aviation...(for the 06z tafs through 06z Tuesday night)
issued at 1105 PM MDT Monday Oct 12 2015

Unseasonably mild and dry conditions will continue across the
region through the next 24 hours with few clouds. Winds will be
relatively light and terrain driven. Specifically...wind flow will
be downslope/downvalley during the night through midmorning and
upslope/upvalley in the late morning through early evening.


Gjt watches/warnings/advisories...

Colorado...freeze warning until 9 am MDT Tuesday for coz002-005-008-014.




Short term...Ben
long term...Ben layers

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