Area Forecast Discussion
Issued by NWS Grand Junction, CO

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272
FXUS65 KGJT 231844
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
1144 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 18Z TAFS through 18Z Friday afternoon)
Issued at 1129 AM MST Thu Feb 23 2017

The cold front has pushed through so now we deal with cold air
advection aloft, gusty winds, and convective showers. Expect gusty
winds to continue through about 00Z as the gradient loosens.
Occasional snow showers will be possible through the next 24 hours
especially for the mountain TAF sites as well as north of the I-70
corridor. When these showers move in, expect MVFR cigs and vis possibly
dropping to IFR under the stronger showers. Outside of KTEX, KASE,
and KEGE, expect varying scattered to broken ceilings over the
next 24 hours. Low clouds will continue for KVEL and will likely
remain so for the next 24 hours along with some patchy fog.

&&

.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...TGR



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