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fxus65 kgjt 211140 
afdgjt

Area forecast discussion
National Weather Service Grand Junction Colorado
540 am MDT Mon Oct 21 2019

Short term...(today through tuesday)
issued at 301 am MDT Mon Oct 21 2019

If you live in the northern mountains of Colorado and like snow
then this forecast is right up your alley. The northwest flow pattern
continues and with sufficient moisture to support snow showers in
the high country. Later this morning an upper-level jet and a
compact wave on the backside of the a deep trough over the central
US pass over the region. The wave and left exit region will provide
enhanced lift across the northern and central Colorado mountains
mainly the Elkhead, park, Flat Top, Gore and Elk ranges. This
forcing is not particularly strong, but it will combine with
orographic lift causing an increase in the snowfall rates beginning
around sunrise and lasting until early afternoon. Surface heating
will steepen the low-level lapse rates and allow for convective snow
showers this afternoon and evening similar to yesterday. The 700 mb
temperatures will be -7 to -10 c, and the dgz appears to stay around
50-75 mb deep with saturation. As a result the snow ratios should
average 10-14:1 through out the event. Wind gusts of 30 to 40 mph
may cause blowing snow especially above the tree line. Rabbit Ears
and Vail passes could become snow covered later this morning so
those traveling should plan accordingly.

By this time tomorrow total snow accumulations will range from 4 to
8 inches generally above 8000 feet in the Elkhead Mountains to 9000
feet in the Elk Mountains. The Park Range could have isolated
amounts close to a foot. Most of the nearby valleys are expected to
receive around an inch, but the upper Yampa River Valley could see 1
to 3 inches by noon. No changes have been made to the Winter Weather
Advisory. For the rest of the forecast area skies will be partly
cloudy north to mostly sunny south. Temperatures will run about 5
degrees warmer than yesterday where there is sun and winds will be
gusty across the area.

Tonight the upper-level jet dynamics push east of The Divide
allowing most of the snow to end. Northwest flow continues with the
potential for a minor shortwave to arrive on Tuesday evening. Most
of the models are indicating light quantitative precipitation forecast in the Elkhead and park
ranges during the day, but there is a lack of forcing and soundings
do not support efficient snowfall. The moisture becomes rather
shallow and midlevel warm air advection looks to decrease the lapse
rates as well as raise the dgz into the drier air aloft. As of now
light orographic snow may persist through Tuesday in the northern
mountains, but it should not amount to much. Cloud cover will remain
entrenched across the northeast half of the forecast area, but where
there is sun temperatures should warm another 5 degrees from today.
The wind will be a little less breezy on Tuesday.

Long term...(tuesday night through sunday)
issued at 301 am MDT Mon Oct 21 2019

An intensifying upper level jet will take a nose dive across the
northern rockies Tuesday night into Wednesday which will pull
another plunge of polar airmass south over our region mid week.
We'll first see an increase in cloud cover from the north Tuesday
night with moisture dipping just south of the Wyoming border by
Wednesday morning. Chances for snow showers over the unitas and
northern and central Colorado mountains increase after sunrise
Wednesday, however the bulk of the moisture will remain to our north
and east. The remainder of the forecast region will experience windy
conditions Wednesday, as the pressure gradient tightens. Highs are
expected to reach seasonably warm temperatures for most of the cwa,
with a strong temperature gradient developing across the northern
tier by Wednesday evening. As the jet intensifies and digs
southeastward, a shortwave trough will pinch off the broad closed
low spinning over northern Ontario, which will allow the polar air
mass to spread south. A cold front will cross the region Wednesday
night into Thursday morning, however the only precipitation with
this frontal passage will be confined to higher terrain along The
Divide and eastward.

A gradual warm up will follow the cold front Thursday through
Saturday, as a ridge of high pressure builds in from our west. The
next shortwave and low pressure system arrives Saturday night, with
initial mositure confined to the northern mountains in northeast
Utah and along the Continental Divide in western Colorado. Models
are favoring a closed low pinching off the tip of the deepening
shortwave, and dropping to our southwest early next week. Depending
on the track of this closed low, we could see widespread
precipitation by Monday into Tuesday, or shoot The Gap between
sources of moisture and stay dry. Guidance is leaning towards a
wetter solution, which is represented by a bump up in pops across
western Colorado Monday evening.

&&

Aviation...(for the 12z tafs through 12z Tuesday morning)
issued at 537 am MDT Mon Oct 21 2019

Another round of light to moderate snow has begun across north
central Colorado. This snow will likely affect hdn, ase, and
possibly Ege and ril. The snow will taper off in the afternoon and
become more isolated through the evening. Periods of MVFR
conditions are expected with the snow and potentially IFR at
times. Elsewhere winds will increase this system tracks over the
area from the northwest.

&&

Gjt watches/warnings/advisories...
Colorado...Winter Weather Advisory until 9 PM MDT this evening for coz004-
010-013.

Utah...none.
&&

$$

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