Area Forecast Discussion
Issued by NWS Grand Junction, CO

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000
FXUS65 KGJT 162143
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
343 PM MDT Mon Apr 16 2018

.SHORT TERM...(Tonight through Tuesday night)
Issued at 343 PM MDT Mon Apr 16 2018

Though winds have been slow to develop today thanks to persistent
cloud cover, we have begun to see wind gusts hit advisory
criteria. Strong winds will continue through the overnight hours
tonight as another potent spring storm rolls in from the west. We
are anticipating that winds may decouple in the valleys somewhat
overnight keeping winds below advisory thresholds, but it is
possible they will gust all night. The front should roll through
the UT/CO border during the mid morning hours on Tuesday when
winds will quickly change from southwesterly to northwesterly. A
line of showers will roll through with the front on Tuesday
morning, bringing rain and snow to mainly northwestern CO favoring
those locations in northwest flow. Weather conditions over the
high passes in Colorado Conditions will stabilize Tuesday evening
with temperatures generally -6 to -8C at 700mb...a cold airmass
for this time of year. Cold, well below normal northwesterly flow
will shroud the region Tuesday night into Wednesday morning.

.LONG TERM...(Wednesday through Monday)
Issued at 343 PM MDT Mon Apr 16 2018

Have issued freeze watches for an expected deep freeze across the
Grand Valley Wednesday morning. Really, everywhere is going to see
a hard freeze, but the Grand Valley is the only zone truly in its
growing season with such a warm spring so far and only one day
below freezing so far this month. Temperatures begin to moderate
later in the day on Wednesday as transitory high pressure builds
over the Four Corners. The progressive roller coaster pattern
continues with the next longwave trough developing over the West
Coast on Wednesday and the development of a closed low over
California. This trough will move eastward on Thursday into the
western Great Basin and will greatly increase southerly winds and
push a warm front northward into eastern UT and western CO.
Forecast models have been consistent on bringing this closed low
in during the late week for awhile, so confidence is decent on
this system. The main cold front will roll through sometime early
Friday, with significant uplift expected to produce convection
Friday afternoon as the closed low moves through the Four Corners.
This system only indicates the lowest temperatures at 700 mb at
-4C, so snow level should be right at mountain bases, impacting
 the usual trouble spots - all mountain passes above 9000 ft.
 Right now, models identify a strong TROWAL signal on the backside
 of this closed low, with significant wrap around precipitation
 possible late Friday into early Saturday. Conditions on the Front
 Range will be much more exciting than here, however the West
 Slope and even eastern Utah may see decent moisture Friday as the
 storm dynamics hop on over to the Front Range.

Drier conditions should develop Sunday into Monday as ridging
builds back across the southwestern US.

&&

.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1145 AM MDT Mon Apr 16 2018

Southwest winds will continue to increase across the region today
with gusts exceeding 50 kts at times. The gusty conditions are
expected to impact all sites with the strongest winds continuing
through at least 04z this evening. Expect areas of turbulence,
especially over the mountains with LLWS possible again Tuesday
morning. Dry conditions are expected with CIGS remaining above ILS
breakpoints through tonight. A strong cold front will sweep
through the area early Tuesday with isolated to scattered showers
developing between 12-18Z. Most activity will be confined to areas
north of I-70.


&&

.FIRE WEATHER...
Issued at 337 PM MDT Mon Apr 16 2018

Windy conditions have not been as high as we thought so far today
due to cloud cover inhibiting significant mixing aloft. However,
many spots are hitting red flag conditions with RH values
in the single digits and wind gusts over 25 mph. In areas where
fuels have been deemed critical, Red Flag Warnings will remain in
effect (Colorado zones 207, 290, 295 and 203 below 6k) until 10 pm
MDT this evening. The windy conditions will persist into the
overnight hours, but RH is anticipated to climb by 10 pm. A
strong cold front will pass through Tuesday morning. Another dry,
warm and windy day is likely on Thursday.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...
CO...Wind Advisory until 10 PM MDT this evening for COZ001>003-
     006>008-011-020-021.

     Red Flag Warning until 10 PM MDT this evening for COZ203-207-290-
     295.

     Freeze Watch from late Tuesday night through Wednesday morning
     for COZ006.

UT...Wind Advisory until 10 PM MDT this evening for UTZ022-024-025-
     027>029.

&&

$$

SHORT TERM...JAM
LONG TERM...JAM
AVIATION...TGJT
FIRE WEATHER...TGJT



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