Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 090445

Area Forecast Discussion
National Weather Service GRAND JUNCTION CO
945 PM MST Fri Dec 8 2017

.SHORT TERM...(Tonight through Saturday night)
Issued at 215 PM MST Fri Dec 8 2017

Mostly sunny skies are prevalent across the forecast area this
afternoon with a few clouds along the divide due to the lingering
disturbance that brought some light snow to the northern and
central divide mountains yesterday. Valley inversions have
strengthened and persisted today with cool but near to below
normal temperatures. The exception to this is Cortez where winds
have been gusting in the 30s to low 40s with temperatures warming
to mid 50s under this downsloping flow. Compare that with Durango
Airport, which is south of Durango and west of Bayfield, which has
a temperature of 40 degrees and light winds. The valleys of NW
Colorado are calm with temperatures still in the 20s in Craig,
Hayden and Steamboat Springs. Quite a difference underneath those
inversions. Expect another cold night and inversions holding
strong again with generally calm winds and excellent radiational
cooling. Saturday will see a slight warmup from today with a light
northerly flow as the high pressure builds and shifts a little
further eastward. Valley inversions will still hold strong keeping
temps cool but nearing normal or slightly above normal which means
mid 40s for the central and southern valleys. Still adjusted temps
downward a bit, trending towards non-bias corrected guidance to
slow this warming trend as the inversions still remain strong.

.LONG TERM...(Sunday through Friday)
Issued at 215 PM MST Fri Dec 8 2017

This coming week continues to look dry as the ridge of high
pressure remains anchored to the western states. Disturbances will
continue to be forced up and over this ridge, which is preventing
any storms from entering the area. By the time these weak
shortwaves make it on the other side, they will weaken and result
in passing high clouds from time to time throughout the week. The
most noticeable disturbance comes Wednesday, which may bring a
slight cool down by mid-week from our peak high temperatures
Tuesday of low 50s for some lower valleys. Temperatures through
Friday will be above normal during the day with much colder, below
normal nights as those inversions strengthen overnight with mostly
clear skies. Still adjusted temps downward to slow the warming
trend due to the persistent mid-level inversions that should
slowly erode day to day.

The big question most everyone is asking is when will this ridge
of high pressure break down to give us a pattern change towards
more precipitation and mountain snow. Well, looking ahead towards
next weekend, the 12Z models are hinting at a disturbance moving
in from the Pacific Northwest, acting to cause a dip in the
amplitude of the ridge. This disturbance looks to clip the
northern divide mountains towards the latter half of next
weekend. There are hints in the latest ensemble runs that point
towards a potential pattern change with the ridge finally
breaking down for the latter half of December as we approach
Christmas. This is still too far out to make any reliable
prediction with any great degree of accuracy and sorry to say, we
have seen this before that far out and it ended up not coming to
fruition. So not biting off just yet. Would like to see more
consistency between models and between runs before declaring it
so as this is the first instance of this occurring.


.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 943 PM MST Fri Dec 8 2017

VFR conditions will prevail across the area for the next 24 hours.
High pressure and north-northwest winds aloft will continue.




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