Area Forecast Discussion
Issued by NWS Grand Junction, CO

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000
FXUS65 KGJT 151718
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
1018 AM MST Sun Jan 15 2017

.UPDATE...
Issued at 1002 AM MST Sun Jan 15 2017

Dense Fog Advisory extended until noon along the US-40 corridor
in northern Colorado based on webcams/surface obs showing thick
fog still in place in many valley locations. While GUC and MTJ obs
have improved, opted to extend advisory in those zones as well
based on webcams showing poor conditions along US 50 and 550,
especially as roads gain elevation higher in the valleys.

&&

.SHORT TERM...(Today through Monday)
Issued at 204 AM MST Sun Jan 15 2017

No change to forecast thinking as models have a good handle on
what`s going on currently. Before getting to the forecast,
important to mention that another round of dense fog advisories
are in place for quite a few areas as visibilities vary from 5
miles down to 1/4 miles at times. Please use caution if travelling
overnight and in the morning hours.  These advisories will remain
in place through 10AM. As far as the forecast is concerned, the
slow moving area of low pressure has now moved to just south of
where Arizona, New Mexico and Mexico meet. Moisture continues to
stream northward but mid and upper level support is just not
strong enough to bring the heavier precipitation into our area.
Now that`s not to say that precipitation won`t reach the area
because it will. In fact, it`s been raining in Pagosa Springs and
Durango for the last hour or two. This trend will continue as the
low pressure starts moving to the northeast as opposed to directly
east. Expect some snowfall over the San Juans with rain for lower
elevations today and by the evening hours, expect precipitation to
overspread to the central mountains. Again, support is very meager
and with easterly flow setting up, favored areas shift to the
eastern San Juans. So do not anticipate much in the way of
accumulation, an inch or 3, but nothing like we`ve seen over the
past week. So the hot spot today looks to be south of Interstate
70 with showers possible away from the mountains. Mostly cloudy
skies are expected in that neck of the woods while areas along and
north of I-70 should see some sun today.

A few showers will persist into Monday morning along the
Continental Divide and San Juans bu they will diminish through the
morning hours. By noon Monday, just about all precipitation will
be done as height rises usher in some high pressure. High
temperatures will drop several degrees as northerly flow brings
cooler air to the region. It`ll be nice to see the sun again! No
worries for you snow hounds. Another active period looks to move
in again late Thursday night.

.LONG TERM...(Monday through Saturday)
Issued at 338 PM MST Sat Jan 14 2017

High pressure will build across the west and lay across the
region from west to east early this coming week, providing dry
conditions for most the region through Wednesday. A weak
shortwave looks to clip the northwest Colorado mountains on
Tuesday with mainly an increase in clouds and the slightest chance
of light snow. Temperatures should moderate by Tuesday into
Wednesday with values closer to normal if not slightly above as
warm air advection takes place ahead of the next series of storms
set to impact the region later this coming week. So before this
occurs, it looks like a dry and quiet period will be in store from
Monday through Wednesday.

Clouds will increase on Wednesday as the flow shifts to the west
ahead of the next series of Pacific storms making landfall onto
the Pacific Northwest and northern California coast. The first in
a series of storms moves across the region Thursday morning
through Friday morning with another one on its heels Friday
afternoon through the weekend. This second one looks stronger as
it deepens and forms a closed low on the lee side of the Rockies.
Details are a little fuzzy since this is a ways out and models
have a tendency to change, but overall it looks like an active and
unsettled pattern takes shape Thursday through the weekend with
more snow in the mountains and a rain/snow mix in the valleys
initially on Thursday, possibly changing to all snow by Friday as
H7 temps lower to around -8C by Friday morning and range from -10C
to -12C by the weekend. Moisture with this next series of storms
is modest but not overly as impressive as the previous atmospheric
river event that kept the weather active the first two weeks of
January. Specific humidity values with this next series of storms
range from 2.5 to 3.5 g/kg. In comparison, the two week long
atmospheric river event averaged about double this amount.
Stay tuned!

&&

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 1002 AM MST Sun Jan 15 2017

Primary aviation challenges this early afternoon will be how to
handle the low cloud decks across the region. Low stratus firmly
in place with MVFR to LIFR conditions in ASE, EGE and MTJ. Short-
term soundings do not show much hope for this cloud deck breaking
in any of these locations through the afternoon or Sunday evening.
Forecast will be status-quo with current ceilings remaining mostly
unchanged through 0z-6z tonight. In fact, with relatively little
flow at all to speak of, these low CIGs may last through the night
into Monday before flow finally turns around to the northwest and
clouds break. No wind issues to speak of for the next 6 hours, and
precip should not be an issue anywhere other than perhaps TEX as
rain/snow will stay mostly east of the divide today.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...
CO...Dense Fog Advisory until noon MST today for COZ002-005-011-014.

UT...None.
&&

$$

UPDATE...MAC
SHORT TERM...TGR
LONG TERM...MDA
AVIATION...MAC



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