Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 051058
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
358 AM MST Mon Dec 5 2016

.SHORT TERM...(Today through Tuesday)
Issued at 358 AM MST Mon Dec 5 2016

Clouds increased over the region early this morning ahead of a
fast moving shallow trough approaching from the northwest. The
cold front associated with this system will just reach the eastern
Uinta Mountains around 12Z, then pushes into northwest Colorado
this morning before eventually stalling somewhere just south of
the I-70 Corridor by 00Z/Tues. Moisture arriving with this system
not all that impressive with just 2.5 g/kg indicated at the 7H
level. As a result...models indicated 1 to 4 inches of snowfall
across the northern mountains today. However, winds will be brisk
ahead of, and just behind the front with sustained winds near 25
kts and, as mentioned in the previous discussion, gusts
approaching 50 kts possible. This will result in widespread
blowing and drifting snow in the high passes today. The southern
mountains and the lower elevations are unlikely to see much if any
precipitation during the day. Except for the north, colder air
won`t reach much of the region in time to reduce temperatures
relative to yesterday.

The stalled front will focus snowfall across the northern mountains
this evening with precipitation winding down during the night with
the lull in snowfall lingering into Tuesday morning. However, a
second more vigorous shortwave trough sweeps across the northern
Great Basin Tuesday afternoon which will bring another round of
snowfall to the northern and central mountains. Steep lapse rates
combined with divergence provided by coupled jet should lead to
periods of heavier snow Tuesday afternoon through Tuesday
evening. Moisture levels remain less than impressive, but still
enough to warrant current advisories, bearing in mind there will
be a prolonged lull later tonight into Tuesday morning.

Expect overnight lows to be colder north of the front and near
persistence south. This pattern holds for Tuesday`s highs as well.

.LONG TERM...(Tuesday night through Sunday)
Issued at 358 AM MST Mon Dec 5 2016

Drying will spread across the region from west to east late
Tuesday night as the trough axis described previously pushes east
of the forecast area. However, light snow showers may linger
along the Continental Divide throughout the day Wednesday before
diminishing Wednesday night. Wednesday should be the coldest day
of the week as the trough just mentioned is expected to drive the
cold front south of the area. It should come as no surprise that
Thursday morning`s lows will also be the coldest recorded this
week.

The airmass begins to moderate Thursday as a shallow ridge forms
over the western states. However, models indicated that a series
of disturbances in northwest flow will bring snow off and on over
the mountain areas beginning Thursday night and continuing through
the weekend. Colorado`s northern ranges will be favored during
this period. Despite the mountain snow, temperatures are expected
to climb back to near normal levels late this week and remain
close to normal into the weekend.

&&

.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1027 PM MST Sun Dec 4 2016

An approaching cold front from the north will change conditions
fairly drastically over the next 24 hours. LLWS may develop
overnight and Mon morning at ASE, EGE, and TEX before mid level
winds mix out. ILS breakpoint will be reached at EGE, RIL and ASE
as showers develop along the front on Monday. Southern CO TAF
sites and CNY will not be impacted much with this first weather
disturbance on Monday, however Tuesday will be a different story.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

CO...Winter Weather Advisory from 9 AM this morning to 6 AM MST
     Wednesday for COZ004-013.

     Winter Weather Advisory from 6 PM this evening to 6 AM MST
     Wednesday for COZ010.

UT...None.

&&

$$

SHORT TERM...NL
LONG TERM...NL
AVIATION...JAM



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