Area Forecast Discussion
Issued by NWS Grand Junction, CO

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602
FXUS65 KGJT 240014
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
514 PM MST Mon Jan 23 2017

.SHORT TERM...(Tonight through Tuesday night)
Issued at 315 PM MST Mon Jan 23 2017

Latest satellite and surface observations indicate a broad area of
low pressure over the Great Basin. A surface low pressure center
is over nrn Utah with an occluded front stretching southeast
toward northeast Utah and a cold front extending south through
eastern UT. Ahead of the front, the atmosphere mixed well in the
lower elevations of southeast UT and portions of western CO with
highs in the lower elevations well into the 40s and near 50.
Vernal, Canyonlands, and Blanding have all had wind shifts and
temperature drops in the last hour or two as a pre-frontal band
of showers moved through. GJT was just hit by this line and went
from near 50 to 35 in a matter of minutes with a rain/snow/pellet
mix. The Durango/Pagosa areas remained near or just below
freezing, so precipitation late this afternoon will likely fall as
mainly snow.

The front will continue marching eastward this afternoon and
likely hang up on the San Juans by midnight. Ahead of the front,
expected rain/snow showers with the possibility of thunder and
graupel. Where it does snow, rates will be briefly high. Winds
aloft are really humming with gusts over 80 mph reported in the
high San Juans. These southwest winds will continue until the
upper level shortwave passes early tonight with winds shifting to
the west and northwest and decreasing. Moisture under the cyclonic
flow aloft will remain over the region through at least Tuesday,
but this event gradually transitions to a northwest flow event and
focuses over the northern and central mountains through at least
Wednesday. With that in mind, extended many of the winter
highlights to various times associated with confidence of
precipitation continuing. Also upgraded the Gore, Park and Flat
Top Ranges to a warning as the moist northwest flow appears to be
ample to provide heavy snowfall through Wednesday.

Not expecting much if any snowfall for the Grand Valley tonight,
and areas south of the San Juans should shut off Tuesday morning
with downslope flow taking over. However, Durango and Pagosa areas
still in line for 4 to 8 inches of snow before then. Higher
elevations in eastern UT and western CO still look good for 1 to 2
foot totals with a great portion of that falling in the next 6 to
12 hours.

.LONG TERM...(Wednesday through Monday)
Issued at 315 PM MST Mon Jan 23 2017

Additional upper level energy drops south from Canada during the
middle of the week, maintaining a genearl north to northwesterly
flow over the region and colder than normal temperatures. Moisture
will continue to ride upslope over northern CO Wednesday through
Thursday, though with increasingly lower amounts. Snow showers
will decrease in coverage Thursday. Models agree on a long wave
ridge amplifying over the West Coast late in the week blocking any
moisture from entering the Central Rockies. Should be a dry
weekend with seasonal to possibly below normal temperatures.

&&

.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 500 PM MST Mon Jan 23 2017

A cold front is marching across the forecast area this evening
bringing some gusty winds...upwards of 45 kts at times...and heavy
preciptiation although they area brief. Once the front passes,
winds will die down and precipitation will lighten up. Even so,
flight conditions for most TAF sites will vary from VFR to IFR at
times under snow showers. A bit of a lull is possible overnight
though low clouds are still expected. Gusts of 60 MPH or greater
at ridgetop level will start to die down overnight.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...
CO...Winter Weather Advisory until 9 AM MST Wednesday for COZ005-010.

     Winter Storm Warning until 9 AM MST Wednesday for COZ012.

     Winter Weather Advisory until 9 AM MST Tuesday for COZ020.

     Winter Storm Warning until 6 PM MST Tuesday for COZ009-018-019.

     Winter Storm Warning until 9 AM MST Tuesday for COZ014-017-
     021>023.

     Winter Storm Warning until 6 PM MST Wednesday for COZ004-013.

     Winter Weather Advisory until 6 PM MST Tuesday for COZ001>003.

UT...Winter Weather Advisory until midnight MST tonight for
     UTZ022>025-029.

     Winter Storm Warning until midnight MST tonight for UTZ028.

&&

$$

SHORT TERM...BEN
LONG TERM...BEN
AVIATION...TGR



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