Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 151917
AFDGJT

Area Forecast Discussion
National Weather Service GRAND JUNCTION CO
1217 PM MST Mon Jan 15 2018

.UPDATE...
Issued at 1214 PM MST Mon Jan 15 2018

The weak cold front bringing the rain and snow to the Front Range
is bringing more cloud cover than originally thought to our
northern areas. Hayden and Craig are reporting ceilings around 3K
to 5K feet though visibile satellite shows these ceilings should
lift over the next few hours. Some snow is also likely falling
over the southern portion of the northern mountains into the
central mountains. Nothing significant expected but did bump up
pops to account for this development.

&&

.SHORT TERM...(Today through Tuesday)
Issued at 148 AM MST Mon Jan 15 2018

A deep trough of low pressure will drop into the Plains and upper
Midwest/Great Lakes area today, with the western edge skirting down
the Front Range in a northerly flow. This will bring much colder air
down the eastern side of the divide, with some of this cooler air
spilling over into northwest Colorado. Some light snow is possible
over the Park and Gore Range, but most guidance is fairly dry with
this system over on our side of the divide with mainly some passing
mid and high clouds. A narrow ridge of high pressure then slides
over the region for Tuesday with dry conditions and continued above
seasonal temperatures.

.LONG TERM...(Tuesday night through Sunday)
Issued at 148 AM MST Mon Jan 15 2018

A weak shortwave moves through the narrow ridge of high pressure
with the GFS taking the energy north and the ECMWF taking the energy
south with this system on Tuesday night into Wednesday. This system
comes through dry with only passing mid and high clouds. The ridge
rebuilds over the area by Thursday and quickly progresses east as a
strong trough of low pressure drops in from the Pacific Northwest
and moves into the Great Basin by Friday. Southwest flow increases
ahead of this system with precipitation entering the region from the
west Friday evening with the cold front moving through Saturday
morning/afternoon. The latest model guidance has slowed this system
down somewhat, allowing it to linger through Sunday morning with
snow persisting over the mountains in northwest flow. The models are
in fairly good agreement on the timing, as well as amount of
moisture and cold air coming in with this system. Specific humidity
values look to be in the 3 to 4 g/kg range with a 125 kt jet driving
this system, bringing in cold air with H7 temps in the realm of -10
to -16C in some areas. This means efficient dendritic snow
production and could be a good snow producer. Something to hope
for...but models still have had a tendency to change so we will have
to wait and see as we get closer.

&&

.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1107 AM MST Mon Jan 15 2018

A weak cold front is moving through the Steamboat Springs/Craig
area at this hour bringing some low clouds to that area. Cloud
heights vary from 3K to 5K feet. Some low clouds are also being
reported at KEGE and may drift into KASE and KRIL over the next
few hours. Do not anticipate conditions to drop into MVFR category
but if they do, they shouldn`t last very long. Once the front
passes, VFR conditions will be the rule for all TAF sites.


&&

.GJT WATCHES/WARNINGS/ADVISORIES...
CO...None.
UT...None.
&&

$$

UPDATE...TGR
SHORT TERM...MDA/JDC
LONG TERM...MDA
AVIATION...TGR



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