Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 211742

Area Forecast Discussion
National Weather Service GRAND JUNCTION CO
1142 AM MDT Sun May 21 2017

.SHORT TERM...(Today through Monday)
Issued at 345 AM MDT Sun May 21 2017

Clouds were beginning to fill in over northeast Utah and northwest
Colorado ahead of an approaching shortwave trough approaching
from the northwest. Otherwise, very little was going on across the
region this morning...for a change. However, as the trough axis
reaches the northern border region of western Colorado and eastern
Utah isolated to scattered showers are expected to develop. This
activity will increase and spread southward while some embedded
thunderstorms develop during the afternoon in response to
decreasing stability and mid-level upward forcing associated with
the southward propagating trough. The higher terrain is favored,
but isolated showers showers are possible over the I-70 corridor
east of Debeque and areas north. Despite increased clouds and
scattered precipitation, afternoon highs are expected to continue
their upward trend, but will still fall below normal for this time
of year.

Showers and thunderstorms will continue into the evening but will
largely diminish during the latter part of the night as the trough
axis moves to the southwest Colorado border by 12Z/Monday.
Isolated to scattered showers and thunderstorms are expected to
break out once again on Monday afternoon as a second, weaker
shortwave brushes the mountains of the Continental Divide.
Overnight lows will continue to moderate while afternoon highs
climb to near seasonal norms during the afternoon.

.LONG TERM...(Monday night through Saturday)
Issued at 345 AM MDT Sun May 21 2017

Apart from an isolated shower or two lingering into the Monday
evening hours along the Divide, drier conditions with clearing
skies will prevail as high pressure begins to build overhead. High
pressure will be in control through at least midweek with
afternoon convective activity remaining minimal. Temperatures
will recover in response to the ridge with above seasonal values

Extended models are beginning to come into better agreement on
having the ridge shift east early Thursday as an upper level
trough digs into the northwestern CONUS, though they still differ
on the intensity of the trough. Southwesterly flow will increase
ahead of this system which could lead to the return of clouds and
convective showers as early as Thursday afternoon. As previous
forecaster mentioned, trends in the timing and location of this
next system will be monitored over the next several days.
Regardless, a return to cooler and more unsettled conditions can
be expected through the long term forecast period.


.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 1122 AM MDT Sun May 21 2017

VFR aviation conditions expected through the early afternoon. A
weak system will increase cloud coverage and ceiling heights will
lower later this afternoon. A few scattered showers may affect
some of the higher elevation terminals. Otherwise, expect a mostly
cloudy overnight and ceilings to rise again by morning. MVFR
appears unlikely however a few ILS thresholds may be met early
this evening.




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