Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 182040

Area Forecast Discussion
National Weather Service GRAND JUNCTION CO
240 PM MDT Wed Oct 18 2017

.SHORT TERM...(Tonight through Thursday night)
Issued at 240 PM MDT Wed Oct 18 2017

Latest satellite imagery early this afternoon shows an increase in
mid and high level clouds across much of the region under
southwesterly flow aloft. The quick moving shortwave trough
responsible for the increased southwest flow today will be moving
across the southern half of the forecast area Thursday afternoon
and evening. Both the atmosphere and this shortwave remain rather
dry and not conducive to any significant precipitation so just
expecting some isolated to scattered showers over the San Juans
throughout the day.

Temperatures will continue to remain above seasonal for this time
of year before the cold front arrives this weekend. More on that
in the long term discussion below.

.LONG TERM...(Friday through Wednesday)
Issued at 240 PM MDT Wed Oct 18 2017

Southwesterly flow will continue to increase on Friday as the
parent Pacific trough and associated cold front dig into the Great
Basin. As the previous forecaster mentioned breezy conditions
will develop during the latter half of the day, especially in
northwest Colorado, as a plus-80 knot upper level jet moves
overhead. Showers will move along the frontal boundary Friday
evening with precipitation favoring the higher terrain for areas
north of I-70. Prefrontal 700mb temperatures will range from 4 to
8 degrees C with those same temperatures plummeting to -3 to -9
degrees C by daybreak Saturday. Unfortunately for snow aficionados
this system lacks significant moisture with storm total snowfall
only reaching 1 to 3 inches for the northern and central Colorado
mountains with some locally higher amounts possible above 10kft.

Showers will gradually diminish Saturday morning as dry
northwesterly flow sets up in the storm`s wake. Extended models
are in agreement with high pressure amplifying over the
southwestern CONUS on Sunday and continuing through early to mid
next week which will keep conditions dry. Temperatures, which
will have dropped down some 10 to 15 degrees below normal behind
the cold front on Saturday, will quickly rebound back to above
seasonal under the building high pressure.


.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 1155 AM MDT Wed Oct 18 2017

VFR conditions will prevail over next 24 hours. Light winds are
expected today with occasional breezes at a few sites in the
afternoon. Mid and high level cloud cover will be present
across southwest Colorado today with increasing clouds tonight
into Thursday as a disturbance approaches from the southwest. Some
isolated showers may develop over the southern high terrain late
Thursday morning and afternoon but should not have any impact on
TAF sites.




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