Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 260912
AFDGJT

Area Forecast Discussion
National Weather Service GRAND JUNCTION CO
312 AM MDT Mon Jun 26 2017

.SHORT TERM...(Today through Tuesday)
Issued at 252 AM MDT Mon Jun 26 2017

Little change as far as the short term period is concerned. High
pressure remains in control bringing another sunny and warm day to
eastern Utah and western Colorado. Once again, a few showers and
thunderstorms are possible over the San Juans but the best
instability and moisture looks to be just to the east of our
forecast area where more widespread convection is expected. The
eastern Uintas may also see an odd shower or storm this afternoon
but these will be very isolated in nature. Expect some gusty winds
to mix down near and under any convection. Outside of these two
areas, plenty of sun continues with a few clouds this afternoon.
High temperatures will increase a few degrees compared to
yesterday.

On Tuesday, the trough mentioned above will move over the CWA. A
bit more convection is possible with the passage of this
disturbance but even the GFS, which is usually very bullish when
it comes to convection, has downplayed precipitation. Looking
aloft, the nose of the upper level jet remains north of our area
and does support more precipitation for the northern Rockies while
we stay fairly dry. As the trough moves through, soundings
indicate good mixing to 500mb, if not higher, where winds of 25 to
35 kts can be found. These will likely mix to the surface,
especially up north, where some gustier winds are expected. With
such dry conditions in place, critical fire weather conditions now
come into play. Please see the fire weather discussion below for
more information.

.LONG TERM...(Tuesday night through Sunday)
Issued at 252 AM MDT Mon Jun 26 2017

The shortwave trough looks to move through the region through
Tuesday evening, ushering in a moderating shot of colder air (with
700mb temperatures dropping some 1 to 3 degrees from Monday night to
the 12 to 16 degrees Celsius range). This will allow for daytime
highs on Wednesday to be slightly cooler, though temperatures will
still be above normal for this time of year. As far as fire weather
concerns go, if the trough exits the area on Tuesday as anticipated,
the upper level gradient will begin to lax behind the trough so
while the atmosphere will still remain exceptionally dry as
precipitable water values range from 0.10 to 0.30 inches, surface
winds do not look to meet critical fire weather criteria at this
time.

For Thursday, the parent upper level low responsible for the
aforementioned embedded trough will drift to the east which will
leave our forecast area in northwesterly flow through the first half
of the weekend as a transitional ridge of high pressure builds to
the south. Saturday evening and beyond, a Pacific trough looks to
dig into the Great Basin with southwesterly flow increasing across
eastern Utah and western Colorado. As the previous forecaster
mentioned, no indication that the dry spell will end anytime soon
which pairs well with the Climate Prediction Center`s 6 to 10 day
outlook which shows odds favoring warmer and drier conditions
persisting through the end of the period.

&&

.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 252 AM MDT Mon Jun 26 2017

Plenty of sunshine with normal diurnal winds. No aviation concerns
over the next 24 hours.

&&

.FIRE WEATHER...
Issued at 252 AM MDT Mon Jun 26 2017

As the trough moves over the area Tuesday, decent mixing up to at
least 500mb will allow some stronger winds to reach the surface.
For the moment, our northern zones look to get the stronger winds
and with dry conditions continuing and very dry fuels, critical
fire weather conditions will likely be met Tuesday. Latest model
runs indicated the Grand Valley and areas of eastern Utah possibly
getting some gustier winds too. However, MOS guidance doesn`t
support these winds while soundings certainly lend themselves to
the chance of it happening. Very borderline at the moment and with
confidence wavering between medium to medium high, will keep the
watches going allowing another model run to come in and see how
winds are looking.

On Wednesday, a second, stronger jet streak is progged to move
over eastern Utah and Colorado and if mixing remains good, these
higher wind speeds may be tapped and reach the surface causing
another day of critical fire weather. A few more model runs will
certainly help in this regard, too.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

CO...Fire Weather Watch from Tuesday morning through Tuesday evening
     for COZ200-202.

UT...None.
&&

$$

SHORT TERM...TGR
LONG TERM...MMS
AVIATION...TGR
FIRE WEATHER...TGR



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