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Area forecast discussion 
National Weather Service Grand Junction Colorado
1033 PM MDT sun Apr 20 2014

Short term...(this evening through Monday night)
issued at 334 PM MDT sun Apr 20 2014

Gjt sounding still showing around 0.60 inches of precipitable water
this morning indicative of the relatively moist airmass. Weak
shortwave currently moving across our forecast area this afternoon
will allow isolated showers and thunderstorms...scattered over the continue into the early evening before diminishing.
We could see some brief heavy rain in some of the strongest storms
along with some gusty outflow winds. Shortwave ridge will move over
the forecast area on Monday with seasonably warm temperatures
expected. However...with adequate moisture in place...we should see
a slow return of shower and thunderstorm activity with only isolated
coverage and mainly over the higher terrain before diminishing early
Monday evening. We could see an uptick in southwest winds Monday
night over the higher terrain ahead of the next system.

Long term...(tuesday through sunday)
issued at 334 PM MDT sun Apr 20 2014

The next upper level low pressure system and an associated cold
front will approach from the northwest on Tuesday. The big story
for this disturbance will be the resulting strong southwest winds
on Tuesday...mixing into the valleys during the afternoon. There
does seem to be a good fetch of middle-high level moisture increasing
over the area through the day ahead of the trough. This cloud
cover may act to inhibit the surface winds. However on the flip
side...any showers/thunderstorms or even virga that develop will
greatly enhance gusts. Therefore gusts 35-45 miles per hour and possibly
higher across favored higher terrain will be expected with the
trajectory right for blowing dust and dust on snow. While the
surface layer generally looks to be on the dry is still
uncertain just how much of the area will drop below critical fire
weather humidity values. See fire weather discussion below. Models
still indicate the track of the upper level trough will remain
mostly to our north on Wednesday. However the models have trended around
6 hours faster with the cold front. It now looks like this surface
front will make it over the northwest corner of the forecast area
by around midnight Tuesday night...then through the remainder of the
area by around midday Wednesday. Since the bulk of the moisture
and upper level support will remain to our north...precipitation
is expected to be isolated to scattered...favoring the mountains
and north.

After a very warm day on Tuesday...cooler temperatures are expected on
Wednesday in the wake of the cold front.

Thursday and Friday look to be calm in-between days with a warming trend
underway as a ridge of high pressure passes over the region. Then
with less forecast confidence...the next trough is prognosticated to
impact the are Sat and sun. Southwest winds will again become
strong ahead of this system on Saturday with an increasing chance
of precipitation through the weekend.


Aviation...(for the 06z tafs through 06z Monday night)
issued at 1031 PM MDT sun Apr 20 2014

Showers have dissipated significantly and will not be a factor
overnight. VFR conditions will prevail through 18z Monday. After
18z isolated weak showers are possible over the mountains...with
VFR conditions expected at all the taf sites and other airports
in western Colorado and eastern Utah.


Fire weather...
issued at 334 PM MDT sun Apr 20 2014

The main fire weather impact for western Colorado and eastern
Utah will be strong southwest winds on Tuesday afternoon as the
gradient tightens ahead of an upper disturbance...and surface
cold front. In addition to the strong winds...very warm
temperatures are expected in this southwest flow. While these warm
temperatures will drive humidity values is uncertain
how much of the area will fall below the critical 15 percent. Also
due to recent precipitation and Spring Green up...fuels in The
Four Corners area...where the lowest humidity is expected...are
no longer critically dry. Therefore will not hoist any fire
weather highlights with this package. That said...localized areas
may meet critical fire weather conditions and caution is advised.
The situation will continue to be monitored.

Due to the earlier timing of the cold frontal passage...winds on
Wednesday are not expected to be as strong as earlier forecasts.

Another approaching low pressure trough may result in strong
southwest winds on Saturday.


Gjt watches/warnings/advisories...


Short term...mpm