Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 241744

Area Forecast Discussion
National Weather Service GRAND JUNCTION CO
1144 AM MDT Sat Mar 24 2018

.SHORT TERM...(Today through Sunday)
Issued at 248 AM MDT Sat Mar 24 2018

GOES Satellite imagery showing flow aloft shifting back to the
southwest across the forecast area with strengthening winds aloft
quite noticeable across Nevada and Utah. These winds will transfer
to the east during the day as long wave trough nudges inland
across Oregon and northern California. Expect surface gradients to
tighten up a bit to help drive a breezy to windy day across much
of the area. The strongest winds will develop across northwest
Colorado, just under advisory criteria based on latest HiRez
solutions. However, we do have the potential for a few showers
this afternoon, favoring the higher terrain. Any activity drifting
across the northwest corner of Colorado could drive the stronger
winds down, resulting in brief gusts in the 40-45 mph range.

The incoming Pacific trough continues to nudge northward with each
model run. Biggest impacts are now confined to our far northern
zones with the Eastern Uinta Mountains in northeast Utah highlighted
as a potential hot-spot for heavier precipitation beginning
Sunday afternoon and evening. Snow levels in this area will
initially be running above 8k, but will lower through the day into
the evening hours as the colder air associated with the incoming
trough arrives. Have nudged pops up in this area and introduced
light accumulations for the higher elevations. The remainder of
the forecast area will see a few mountain showers Sunday afternoon
with generally dry conditions anticipated for the valleys.
Temperatures will be on the warm side of normal for the next few

.LONG TERM...(Sunday night through Friday)
Issued at 248 AM MDT Sat Mar 24 2018

A shortwave trough will move across the northern Rockies Sunday
evening into Monday morning, generating some scattered showers
over northeast Utah into northwest Colorado. This shortwave
trough is further north than in previous model runs and seems
fairly weak and disorganized. By Monday, an upper level trough
will drop southward across the area with cooler air advecting
into the region under a northerly flow. This upper level trough
has also shifted further east than in previous model runs, which
means the colder air will filter over our region. This trough is
still wanting to form a closed low over Arizona by Monday
evening, causing the trough to split from the main flow. The
downside of this is that all the energy from the upper level jet
will be to our southeast, resulting in our CWA in the unfavorable
right entrance region which is more subsident. So, with a lack of
dynamical forcing and weak orographics, not expecting much in the
way of significant precipitation over the region. Scattered
convective showers, favoring the central and southern high
terrain, look to be the most likely solution on Monday and
Tuesday as this trough drops southward and the closed low moves
from Arizona into New Mexico by Tuesday. As this happens, the
flow will shift to easterly which will direct the better moisture
and lift along the eastern San Juans and east slopes of the
central Colorado divide mountains. Easterly flow is not favorable
for our region at all as we end up becoming shadowed with less
precipitation on our side of the divide. We are also stuck in the
col region, or deformation zone, which is also unfavorable. This
system moves out by Tuesday night as another more robust
shortwave invades from the northwest on Wednesday, bringing good
orographic snowfall to the northern and central Colorado
mountains with northwest slopes favored.

Confidence in the Monday and Tuesday system is still fairly low
as it remains very disorganized with subtle changes from run to
run. All in all, the models have been trending weaker and more
disorganized with this system each day. Confidence is also low in
how this shortwave Wednesday will play out as models have been
inconsistent the past few days. The ECMWF is more robust and
further west with this shortwave, while the GFS favors the
northwest Colorado mountains and the Canadian barely clips our
area with this feature. So, quite the range in solutions. The
pattern will be unsettled, however, Monday through Thursday
morning. A strong and amplified ridge of high pressure looks to
build across the western states by mid-week and influence our
weather towards the end of the week with drier and milder air
returning. Temperatures throughout the period will be cooler with
near to slightly below normal readings Monday through Wednesday,
before bouncing back to above normal by the end of the week into
next weekend.


.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1144 AM MDT Sat Mar 24 2018

VFR conditions are expected to prevail at all TAF sites through
Sunday afternoon. Mid and high level clouds will continue to
increase throughout the day under moist southwesterly flow.
Isolated mountain showers will develop after 20Z and persist
through this evening. Gusty southwest winds will also develop
across the region with the strongest wind gusts expected across
northwest Colorado where speeds may exceed 35 kts at times.




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