Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 192154

Area Forecast Discussion
National Weather Service GRAND JUNCTION CO
354 PM MDT Wed Apr 19 2017

.SHORT TERM...(Tonight through Thursday night)
Issued at 353 PM MDT Wed Apr 19 2017

Water vapor showing a smaller scale wave being pushed across the
Eastern Great Basin by the arrival of a stronger upstream kicker
storm to the Pac.Northwest coast. This wave will keep isolated to
scattered showers going across the northern half of our CWA
through the evening...dissipating after sunset with the loss of
heating and lift. The cold front that entered the CWA last night
is slowly progressing toward the southern CO/UT border where it
will become diffuse overnight. The upstream storm system will be
dropping into the northern Great Basin tomorrow with the height
falls to the west increasing the southerly winds over our region.
The surface boundary stalled in the south will lift as a
pseudo-warm front by early tomorrow afternoon. Ascent increases
dramatically over SW.Colorado after noon as the nose of jet begins
it/s cyclonic turn across the 4 corners into the Plains. Initial
moisture is quite sparse and the showers and storms should be high
based and initially limited in coverage. The showers or virga will
help bring wind to the ground and this should lead to a
breezy/windy afternoon. The cold front approaching the Wasatch by
mid afternoon will also help tighten gradients and focus the
strongest warming over the 4 corners region. Dry fuels in this
region when combined with the dry and windy conditions has
prompted the upgrade to Red Flag Warnings in the south. A Fire
Weather Watch remains in the Montrose-Delta-Grand Valley areas as
confidence is wavering on afternoon humidity levels dropping low
enough for critical conditions to be met. The cold front will
quickly plow southeast across the CWA late tomorrow afternoon
through the late evening hours. This fropa will enhance the wind
conditions and strong gusts can be expected to be enhanced by the
precipitation. Large scale ascent in maximized with and just
behind the fropa over the northern and central Colorado mountains.
Cold air quickly infiltrates the soundings and profiles become
favorable for accumulating snow from pass level down to mountain
bases and high valleys. Impacts to travel at the high elevations
overnight look very probable at this time but getting critical
snow accumulation levels are still somewhat problematic with the
warm temperatures. High peaks from the West Elks to the Park
ranges should be fairly white up top by the time this system rolls

.LONG TERM...(Friday through Wednesday)
Issued at 353 PM MDT Wed Apr 19 2017

Temperatures will drop 10 to 15 degrees on Friday on the back side
of this front. Instability and orographics will continue to
utilize any moisture in the channelized vorticity area aloft to
keep high elevation snow and valley rain showers going through the
afternoon. North facing slopes and the curve of the Elk/Sawatch
ranges will be favored through sunset before we push in more
stable air aloft. Ridging for the weekend once again gives away to
a quick moving system early next week. Precipitation chances are
still favored across the northern Rockies at this time. From mid
to late week strong ridging over the oceans looks to favor a large
and cool trough digging across the core of NOAM. This pattern is
still favoring a robust Spring storm in the middle to late part of
next week. Stay tuned.


.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 1139 AM MDT Wed Apr 19 2017

Scattered showers with a few embedded thunderstorms will continue
over the northern and central Continental Divide this afternoon.
A shower is possible at KASE early this afternoon which could
result in a brief period where CIGS fall below ILS breakpoints.
Otherwise, TAF sites will experience VFR conditions and CIGS above
ILS breakpoints through the next 24 hours.


CO...Fire Weather Watch from Thursday afternoon through Thursday
     evening for COZ203-292.

     Red Flag Warning from 1 PM to 8 PM MDT Thursday for COZ207-290.



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