Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 230544

Area Forecast Discussion
National Weather Service GRAND JUNCTION CO
1144 PM MDT Sat Apr 22 2017

Updated aviation and fire weather sections

.SHORT TERM...(Tonight through Sunday night)
Issued at 220 PM MDT Sat Apr 22 2017

This morning`s 12Z H500 hand analysis had ridging moving into our
eastern CWA. This ridge will remain transitory moving over the
Rockies into the Plains over the next 24 hours. This shift brings
a stronger southwest gradient to the pattern by Sunday afternoon
as the next system shifts out of the Pacific NW. Moderate
instability in place will lead to a warm and windy day with highs
likely warming by around 10 degrees in most places. As a result
critical fire weather conditions are highly probable over portions
of SW Colorado where fuels are receptive to fire. The upstream
system will be barreling across the northern CWA Sunday night
bringing a bit of mid and high level moisture along with it. The
best precipitation chances remain north of interstate 70 with the
high terrain favored with this first in a series of storms.

.LONG TERM...(Monday through Saturday)
Issued at 220 PM MDT Sat Apr 22 2017

Confidence extremely high for a pattern change next week but
becoming increasing low over some of the exact changes that will
be impacting our region. Again strong ridging over the North
Atlantic and Eastern Pacific will carve out a broad and cold
trough over the western 2/3 of the CONUS by mid week. The coldest
air in the hemisphere will be piled over the North Pole to the
Hudson Bay area and will almost guarantee some of the upcoming
forecast will be well below normal. The models are really
struggling with this pattern change in how energy is dropped into
and rotated out of the larger mean trough. On track is a brush by
system on Monday followed by a more amplified trough passage on
Tuesday which should impact more of the CWA. Temperatures appear
cold enough to get snow down to mountain bases again through
better accumulations likely well above that. The movement of this
system to the east begins the downturn in confidence and will not
even try to describe the model differences. However the 6 to 10
day outlook favors above normal precipitation and below normal
temperatures happening than not.


.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1144 PM MDT Sat Apr 22 2017

VFR conditions will prevail over the next 24 hours. Southwest
winds will increase Sunday afternoon as high pressure in place
breaks down with active weather returning on Monday. High clouds
will increase throughout the day Sunday, with LLWS expected to
develop around or after 00z Sunday across the San Juans including


Issued at 1144 PM MDT Sat Apr 22 2017

Temperatures will continue to warm on Sunday reaching the upper
70s to low 80s in the Grand Valley and relative humidity values
will fall as southwesterly winds increase ahead of an approaching
storm system. Afternoon minimum relative humidity values will
struggle to get out of the teens across much of the forecast area.
These warm dry atmospheric conditions combined with dry fuels in
western Colorado will lead to critical fire weather conditions on
Sunday. Therefore, a Red Flag Warning is out for Fire Weather
Zones 203, 207 and 290 in central and southern portions of Western
Colorado where fuels are being reported as dry. For more detailed
information please see the Red Flag Warning on our web page; or see DENRFWGJT.


CO...Red Flag Warning from 1 PM to 8 PM MDT Sunday for COZ203-207-290.



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