Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 211734

Area Forecast Discussion
National Weather Service Grand Junction CO
1134 AM MDT Sat Sep 21 2019

.SHORT TERM...(Today through Sunday)
Issued at 407 AM MDT Sat Sep 21 2019

Dry and cooler conditions will occur today as the trough continues
to depart the region. The gradient will be much more relaxed,
allowing winds to lessen considerably compared to yesterday. Some
isolated storms are possible over the eastern Uintas this
afternoon, but aside from that, the dry and cool air mass with
less wind will be a welcome change. Latest guidance came up a bit
with the low temperatures tonight into Sunday morning across the
northern Yampa River valley. This puts low temps hovering around
the freezing mark in Craig and Steamboat while the majority of
those zones down towards Meeker remain in the mid 30s. Decided to
hold off on issuing any Freeze Watch tonight due to limited
spatial coverage as the coldest temps look to be localized along
the Yampa River. Also, temperatures this morning are in the low to
mid 30s in Craig, Meeker and Steamboat where a Freeze Warning
remains in effect through 9 am. Would like to wait and see how the
current Freeze Warning pans out and see how model guidance trends
in the next run or two. There may be enough mixing overnight to
keep temps near to slightly above freezing due to the upper level
jet overhead. A transitory ridge of high pressure slides over the
region Sunday, providing for a slight bump up in temperatures and
another dry and sunny afternoon.

.LONG TERM...(Sunday night through Friday)
Issued at 407 AM MDT Sat Sep 21 2019

Southwest flow will increase Sunday night into Monday as a trough
of low pressure drops from the Pacific Northwest into the southern
Great Basin. Models are coming into better agreement on the timing
and placement of this system, showing the low dropping further
south and west, settling southwest of the Four Corners over
Arizona late Monday through mid-week. This keeps the majority of
the precipitation out of our CWA. Reduced the PoPs in coordination
with neighboring offices for the Monday afternoon through Tuesday
morning period due to this trend. Decided to still keep isolated
to scattered showers and storms focused more across southeast Utah
and southwest Colorado late Monday as this low drops southward.
The low tries to close itself off over Arizona Monday night into
Tuesday and even dives further south towards southern Arizona and
the northern Baja in Mexico. This keeps areas north of the Four
Corners (so basically our entire CWA) in the deformation area with
dry conditions and temperatures near normal. The low then lifts
northeast as an open trough across the Four Corners into southwest
Colorado and to the Front Range on Thursday, bringing us our best
chance of precipitation. This system is much warmer though than
previous runs so snow levels will be fairly high. Did raise the
PoPs a bit from the blended solution on Thursday due to this
trough passage, but still remain at slight chance due to the model
disparity as the ECMWF is not quite as robust as the GFS. Also,
as we`ve seen the last few days, model solutions can change as we
get closer to that time.


.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1134 AM MDT Sat Sep 21 2019

Winds become mildly breezy at most TAF sites across eastern Utah
and western Colorado again this afternoon but winds will
definitely be less strong than on Friday. Clouds will be mid to
high based with no precipitation expected, except over the eastern
Uinta Mountains during the afternoon and early evening.
Therefore, expect VFR conditions with CIGS above ILS breakpoints
at all TAF sites across the region through the next 24 hours.






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