Area Forecast Discussion
Issued by NWS Grand Junction, CO

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622
FXUS65 KGJT 242122
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
322 PM MDT Fri Mar 24 2017

.SHORT TERM...(Tonight through Saturday night)
Issued at 300 PM MDT Fri Mar 24 2017

Daytime satellite imagery shows a departing low pressure system
centered over the southern high plains. Clear skies are on place
over eastern Utah and far western Colorado with a bit of
lingering cumulus cloud cover in the Colorado high country.
Aloft, a shortwave ridge will quickly traverse the region this
evening with clear skies expected for the first half of the night.
Combined with a decrease in winds in the valleys, this will allow
temperatures to cool off rapidly early this evening after sunset.
Not expecting freezing temperatures in the Grand Valley and
points westward along the Colorado River, but higher mountain
valleys will certainly experience their coldest night in several
days.

High cirrus clouds will quickly spill over into the region after
midnight tonight as heights fall ahead of our next weather system.
This cloud cover will limit low temperatures early, with morning
temps perhaps even rising a few degrees before sunrise Saturday.
Cloud cover will thicken through the day on Saturday with
precipitation beginning first in the eastern Uintas by noon, and
into the higher elevations of western Colorado by 6pm. Short term
forecast guidance has settled on around 0.1 to 0.25 inches of
liquid with this storm for the mountains, with valleys likely
seeing only a hundredth or two due to an abundance of dry air at
the surface. Snow levels will start off around 9000 feet but will
fall to around 7500 feet by midnight Sunday, with around 1-3
inches of snow expected for the San Juans, central Colorado
mountains, and the Flat Tops.

.LONG TERM...(Sunday through Friday)
Issued at 300 PM MDT Fri Mar 24 2017

Precipitation will wind down over western Colorado during the
early morning hours on Sunday morning as lee cyclogenesis
initiates over the eastern high plains. Northwesterly flow and a
bit of lingering moisture around 700mb may keep some snow shower
activity going in the central and northern mountains near the
divide through 6pm. Otherwise, a dry day is expected for the
valleys with temperatures right around average for late March.

Weak ridging will move through the central Rockies on Monday
morning before our next (and more complicated) storm system moves
in for midweek. Several pieces of energy will come ashore along
the Pacific northwest early in the week, with the final and most
significant vorticity maximum diving into the desert southwest on
Tuesday. Guidance has varied significantly over the past several
days with regard to the strength and depth of this system. Today,
some clarity has been realized as all three major global models
now show a cutoff low at 500mb centered just south of the Four
Corners region by Tuesday afternoon. Precipitation onset time will
vary depending on elevation, with the higher terrain seeing a few
showers as early as Monday afternoon, and the valleys (including
Grand Junction, Montrose, and even Durango) by 6pm Monday. The
cutoff low pressure will deepen and slow significantly over
northern New Mexico through the day on Tuesday, bringing an
extended period of light to moderate precipitation to the central
Rockies, especially in southern Colorado. Ensemble guidance has
remained consistent in showing 500mb heights near 2 sigma below
mean seasonal values over the southwestern CONUS with this
system. The result will be cooler temperatures aloft and the
opportunity for another early spring snowfall event in the higher
terrain. Exact snowfall totals are still uncertain at this time,
however a mean of available guidance suggests around 0.5 to 1 inch
of liquid in the higher elevations above 9000 feet with this
system.

By midnight Thursday morning, guidance indicates precipitation
should be winding down over the central and southern ranges in
Colorado. Unsettled northwesterly upper-level flow appears to
remain in place behind this system however, with yet another storm
system moving in on its heels by Thursday evening into next
Friday.

&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 1136 AM MDT Fri Mar 24 2017

This morning`s storm system is now centered over the Panhandle of
Texas placing Eastern Utah and Western Colorado in dry air. This
is resulting in improving sky conditions which should remain VFR
through the next 24 hours. Winds should be generally light but
gusts will be possible into the evening hours.


&&

.GJT WATCHES/WARNINGS/ADVISORIES...
CO...None.
UT...None.
&&

$$

SHORT TERM...MAC
LONG TERM...MAC
AVIATION...Larry



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