Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 191009

Area Forecast Discussion
National Weather Service Grand Junction CO
309 AM MST Mon Nov 19 2018

.SHORT TERM...(Today through Tuesday)
Issued at 309 AM MST Mon Nov 19 2018

Dry northwest flow will dominate today through Tuesday as high
pressure remains nearly stationary over the Great Basin. High
temperatures will remain a few degrees below normal today but warm
up to a bit above normal Tuesday. Overnight low temperatures will
drop well below normal again tonight under clear skies.

.LONG TERM...(Tuesday night through Sunday)
Issued at 309 AM MST Mon Nov 19 2018

The models have made a very slight northward trend in the past 12
to 24 hours in respect to the Thanksgiving Day system. However the
large scale forcing pattern is completely out of phase going into
the weekend and have very little confidence attm. The EURO remain
the brute of the model suites and keeps a much less progressive
pattern in place. This solution would be somewhat favorable for
our CWA but much better news for the lee of the Rockies. The GFS
has the support of the NAEFS though this ensemble shows plenty of
variability back of the 4 Corners going into the weekend as well.
Overall the more progressive and consistent GFS is favored attm
which means the northern and central mountains are the most
probable to benefit from this pattern. Status quo. There is much
better detail in the previous discussion and it follows:

Into early week the upper ridge gradually shifts eastward along with
a low pressure that passes south of the forecast area along the
US/Mexico border. The models are fairly consistent keeping the
precipitation associated with that low pressure across southern New
Mexico on Wedensday. By mid week several shortwave troughs work
towards the west coast. One of these troughs is forecasted to
track over the area on Thursday bringing valley rain and mountain
snow with the western slopes being favored for orographic lift.
The 700 mb temperatures will start around -5 to -3 C as the
trough arrives during the day Thursday. As a result snow levels
should range from around 5000 feet across northeast Utah to around
7000 feet in southern Colorado as the precipitation develops. As
cold air continues to filter in the snow levels will lower
overnight. The modest QG forcing passing over the region will be
progressive so enhanced precipitation rates will be brief.
Despite that there could be enough snow for travel impacts
Thursday evening into Friday. One big concern is the potential for
moist upslope flow to persist through Saturday. Into the weekend
a more amplified shortwave begins to drop southeastward from the
Pacific Northwest. This increased forcing within the northwest
flow will arrive on Saturday. The models begin to diverge on the
evolution of this wave with the ECMWF showing the system closing
off over the Four Corners, while the GFS shows a more open wave.
This time frame will need to be closely monitored with the
potential for more widespread impacts.


.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 309 AM MST Mon Nov 19 2018

VFR conditions will prevail across the area for the next 24 hours
under nearly clear skies.




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