Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 210538

Area Forecast Discussion
National Weather Service Grand Junction CO
1138 PM MDT Sat Oct 20 2018

.SHORT TERM...(Tonight through Sunday night)
Issued at 110 PM MDT Sat Oct 20 2018

Benign weather will continue for the next 24 hours with generally
light winds and mostly sunny skies. Temperatures have recovered 5
to 10 degrees from this time yesterday, though highs today will
still remain at or slightly above climatological normals. The
upper level ridge axis is still projected to shift east late
tonight through Sunday as a trough of low pressure pushes into
California. This will allow high level clouds to increase over the
Four Corners area tonight before spreading northeast throughout
the day Sunday. High resolution models are keeping conditions
mostly dry tomorrow, though some isolated showers will threaten
to intrude upon the Utah/Arizona border by the early to mid
morning hours. Isolated showers will remain in the forecast for
the Four Corners throughout the day on Sunday with coverage
becoming more scattered over the higher terrain (namely the La Sal
and Abajo Mountains as well as the Tavaputs Plateau) by Sunday
night as a better push of moisture is ejected out ahead of the
low. As the low continues to progress into the Great Basin late
Sunday, overnight lows Sunday night will be a few degrees warmer
in response to increased clouds.

.LONG TERM...(Monday through Saturday)
Issued at 110 PM MDT Sat Oct 20 2018

The cut-off upper level lower pressure center that is currently
over California will continue to slowly move east and open up
Monday as the ridge to its north and east begins to break down and
shift east due to a strong upper level jet moving east across the
north Pacific breaking down the blocking pattern. Weak dynamics
and lift Monday in the southwesterly flow aloft over our area
ahead of the upper level trough will increase chances for
showers...especially across eastern Utah. As the upper level
trough starts to move across the region Tuesday and Tuesday night,
moisture, upper level jet and mid level dynamics are maximized
over the region and will result in greatest coverage of showers
and precip amounts in excess of one half inch likely over the San
Juan Mtns. With 700 mb temps staying above 2C, the snow level
should remain between 9,500 and 10,000 ft and result in little if
any impact on major passes.

Northwest flow in the wake of the exiting trough may yield a few
showers for northern areas Wednesday/Thursday, but should not be a
big deal. Friday into Saturday, models agree on an upper level
high setting up off the coast of SoCal and extending northeast
over our area. However, a strong jet and storm track sets up to
the north over the Pac NW into the northern Rockies. Will have to
see exactly where these features set up as a weaker ridge may let
the unsettledness move farther south into our area.

Where it is not too cloudy Monday, temperatures will rise to a
few degrees above normal. Tuesday should be cooler than normal due
to clouds/showers being fairly widespread. As northwest
flow/ridging sets up Wed-Sat, temperatures should be at least 3 to
5 degrees above normal.


.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1137 PM MDT Sat Oct 20 2018

VFR conditions will prevail for the next 24 hours. Some cumulus
and high cirrus will move in from the south overnight with
scattered coverage by afternoon. Conditions will remain dry with
no impacts to flight operations. Winds will generally follow
terrain-driven diurnal patterns and remain fairly light.




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