Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 182304
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
504 PM MDT Sat Mar 18 2017

.SHORT TERM...(Tonight through Sunday night)
Issued at 358 PM MDT Sat Mar 18 2017

Another record setting day as anticipated with many lower valleys
reaching the mid to upper 70`s and some locations creeping above
80! Grand Junction was one of those areas. In fact, this is the
earliest recorded occurrence of 80 degrees for Grand Junction,
whose climate record dates back all the way to 1893! The higher
elevations have also been seeing impressive warmth with elevations
above 9000ft climbing to the upper 50`s to low 60`s.

The ridge of high pressure responsible for the continued warmth
remains overhead but latest GOES-16 satellite imagery shows the
axis beginning to shift east this afternoon. Southwesterly flow
will pick up after midnight tonight as the gradient tightens
aloft. As a result, Sunday will be another warm, breezy day. As
previous forecaster mentioned, daytime highs will dip slightly as
a result of an increase in mid and high level clouds streaming
across the region. This will also lead to mild overnight lows on
Sunday night with some locations not dropping below 50.
Regardless, both highs and lows across western Colorado and
eastern Utah will remain some 10 to 20 degrees above seasonal
norms through the short term period.

A very weak, small-scale, embedded disturbance in the
southwesterly flow will work through the region on Sunday. Apart
from aiding in increasing cloud cover further north and the
potential for virga, this wave will pass out of the area without
any fuss.

.LONG TERM...(Monday through Saturday)
Issued at 358 PM MDT Sat Mar 18 2017

The arrival of the new work week begins the transition from a quiet
March to a more progressive weather pattern. Strong southwesterly
flow will bring another embedded shortwave on Monday. While this
disturbance is not strong and lacks substantial moisture and
energy, it should be sufficient enough to generate some isolated
to even scattered (if going with the continued bullish GFS
solution) showers over the mountains with the central Colorado
mountains favored. 700mb temperatures with this shortwave range
from 3 to 6 degrees C so any precipitation is expected to fall as
rain with snow showers isolated to the highest mountain peaks
above 10kft. A weak, dirty ridge builds in for 12 to 18 hours on
Tuesday as the broad Pacific trough that will be impacting our
area the latter half of the week moves inland.

Southwesterly flow will increase ahead of the aforementioned Pacific
storm on Wednesday with the nose of a ~100kt jet arriving Wednesday
morning. This will result in some gusty prefrontal winds
persisting through Thursday. The southwesterly flow will also
result in increased cloud cover and the chance for precipitation
with showers, albeit orographic showers for now, developing as
early as Wednesday morning. Extended models continue to disagree
on timing, setup, and track of the event with the GFS being more
progressive and kicking the trough through the region by Thursday
night and the Euro lagging behind at least 6 to 12 hours, bringing
the storm axis further south. Regardless, this still looks to be
the first impressive storm the region has seen in a while with
numerous to widespread precipitation expected for western
Colorado and eastern Utah Wednesday and Thursday. Precipitable
water values look to peak from 0.50 to 0.70 inches or 167 to 233%
above normal. 700mb temperatures drop to -2 to -5 degrees C
Thursday afternoon before the bulk of the colder air moves in on
Friday when 700mb temperatures drop to the -5 to -10 degrees C
range. Snow level forecast remains tricky with this warmer system
and, since the models continue to differ on frontal passage,
precipitation type and estimated snowfall accumulations for those
higher valleys will have to be hashed out later. With regards to
temperatures, the passage of the cold front towards the end of
next week will knock temperatures back down to their seasonal
norms, or at least a little closer to them.

As for the rest of the extended forecast, drier conditions look to
return for Friday and Saturday as a weak ridge builds over the area.
This ridge will not persist as yet another longwave trough moves
into the region by the end of next weekend as the progressive
weather pattern continues. This is supported in both the 6 to 10 day
as well as the 8 to 14 day Climate Prediction Center Precipitation
outlooks, which both hint at odds favoring above normal
precipitation for much of the western CONUS. So while March may not
have come in like a lion it appears it may go out as such!

&&

.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 504M MDT Sat Mar 18 2017

Gusty west to southwest winds will diminish by 02Z. Otherwise,
expect VFR conditions with CIGS above ILS breakpoints for all TAF
sites through the next 24 hours. Winds will become breezy again
after 18Z at all TAF sites except KVEL.

&&

.FIRE WEATHER...
Issued at 358 PM MDT Sat Mar 18 2017

The ridge of high pressure will shift east to the Plains today.
This will allow southwest winds to strengthen over the region
tomorrow afternoon. Relative humidities are expected to drop into
the 15 to 25 percent range tomorrow afternoon, but may drop lower
with record or near record heat persisting. The gusty winds
combined with warm temperatures, low humidity and still dormant or
dry vegetation will require a heightened fire weather awareness.
Check the latest forecast before attempting any burning through
this weekend as conditions can change rapidly. The potential will
be greatest for elevations below 8000 feet.

&&

.HYDROLOGY...
Issued at 358 PM MDT Sat Mar 18 2017

Prolonged period of record or near record high temperatures will
continue to impact the region through tomorrow. This will
accelerate snowmelt resulting in increased flows on area waterways
and slow but steady rises in river levels. Temperatures are
expected to cool next week as clouds and the chance for showers
return to the area, which will help to slow the snowmelt. A storm
carrying major moisture potential is possible during the middle
of next week in the form of both rain and snow. Will need to
monitor for rain on snow issues that could develop mid to late
next week with the changing snowpack levels.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...
CO...None.
UT...None.
&&

$$

SHORT TERM...MMS
LONG TERM...MMS
AVIATION...NL
FIRE WEATHER...TGJT
HYDROLOGY...TGJT


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