Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 231059
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
359 AM MST Thu Feb 23 2017

.SHORT TERM...(Today through Friday)
Issued at 327 AM MST Thu Feb 23 2017

Stand up cold front is sweeping across western Colorado this
morning being driven by a circulation over S.Wyoming. Water vapor
does show an upper level circulation over S.Idaho which will
basically integrate with the one in Wyoming through the morning
and early afternoon hours. Both moisture and cold air aloft will
continue to wrap around the back side of this circulation into
our CWA with the best gradient of the two remaining north of
Interstate 70. Quick shot of wind and precipitation from CNY to
GJt to RIL this morning with the fropa but little if any of it
measurable so far. Overnight webcam views showed accumulations
mainly on grassy surfaces in the Uinta Basin with some slush on
the roadways. Coldest air will stay in place up north this will be
area of concern with the moisture and instability staying in
place. Current metar at EEO show potential for heavier snow but
would like a look at daylight for impacts. Coverage this afternoon
may not warrant an advisory for snow but will be prepared to hoist
one after sun comes up. The cold advective...unstable
west/northwest flow will not really ease up until late Friday
evening. Expecting a bit more snow in the hills than currently in
our advisory and will bump up with some areas possibly pushing a
foot by Friday afternoon. Again the showery nature of the
precipitation leaves this a low confidence forecast. Temperatures
will cool significantly behind the front however with highs today
forecast to be 15 to 20 degrees cooler than 24 hours ago. Highs on
Friday may even be a few degrees cooler yet.

.LONG TERM...(Friday through Wednesday)
Issued at 348 PM MST Wed Feb 22 2017

An embedded wave in the northwesterly flow will allow clouds and
showers to linger on Friday and continuing through early Saturday.
Precipitable water values associated with this disturbance range from
0.15 to 0.20 inches which is slightly below normal, so not too
impressive at the moment. Upper level support is also not there as
the jet remains well south of the area. Therefore, generally
orographic showers look to be the main concern on Friday with the
northern and central mountains favored. Tightening westerly flow
aloft will result in dry conditions and a breezy afternoon on
Saturday as the tail of a +110kt jet moves in.

A progressive pattern will begin on Sunday and looks to continue
through at least Tuesday. This will consist of a weak shortwave
trekking across the forecast area on Sunday with southwesterly flow
increasing on Monday ahead of our next significant storm. While
extended models differ on the intensity and arrival of the
approaching Pacific trough general consensus has the system digging
into the Great Basin and impacting the region as early as Monday
night. As the previous forecaster mentioned this suggests a
return to unsettled conditions and the potential for moderate to
heavy precipitation. Something else to note; 700mb temperatures
associated with this storm range from -10 to -14 deg C so if this
pans out it could bring us a nice cold spell!

&&

.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1051 PM MST Wed Feb 22 2017

A cold front associated with the latest winter storm will largely
be driving the weather at TAF sites across the area through the
next 24 hours. The front is expected to sweep southeastward across
the area during the night, exiting to the south of the Colorado
border by 12Z/Thursday. Ahead of the front expect gusty west to
southwest winds at 15 to 25 mph with gusts to 35 mph. In the
higher elevations winds will be quite strong with the jet stream
moving overhead resulting in wind shear at a number of sites. Best
chances for precipitation will come with frontal passage which is
likely to bring MVFR CIGS/VSBY with periods of IFR conditions and
a prolonged period where CIGS will be below ILS breakpoints.
Conditions improve at all sites after 18Z/Thursday. Detailed
information regarding timing and impacts can be found in the TAFs.


&&

.GJT WATCHES/WARNINGS/ADVISORIES...
CO...Winter Weather Advisory until 9 AM MST Friday for COZ003-004-013.

UT...Winter Weather Advisory until 6 PM MST this evening for UTZ023.

&&

$$

SHORT TERM...15
LONG TERM...MMS
AVIATION...NL


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