Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 280013
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
613 PM MDT MON JUN 27 2016

.SHORT TERM...(Tonight through Tuesday Night)
Issued at 330 PM MDT Mon Jun 27 2016

Elongated ridge will dominate these periods, centered near the
Four Corners. Very dry air is in place over the forecast area this
evening. Isolated thunderstorms in the marginally better moisture
over the southern San Juans will collapse around sunset. The drier
GFS seems to be handling the onset of the moisture surge the best.

Tuesday the weak upper flow turns from north to south-southeast.
This allows monsoonal moisture to invade into the Four Corners
through the day. Initially this moisture looks to be in the mid-
upper levels so the lowest elevations will still have dewpoints in
the 30s with little rain expected to reach the ground. These dry
thunderstorms will favor SE Utah but far SW Colorado may also see
mostly dry thunderstorms.

Tuesday night moisture deepens over eastern Utah and far western
Colorado keeping showers and thunderstorms going through the
night.

Meanwhile an inverted trough over southern California will slowly
work northeastward around the western edge of the ridge into
the western Great Basin.

.LONG TERM...(Wednesday through Monday)
Issued at 330 PM MDT Mon Jun 27 2016

The Four Corners High remains through this week. Starting
Wednesday though, disturbances working through the ridge dominate
our weather. The inverted trough, over southern California today,
shears into the central forecast area Wednesday into Thursday.
Deeper moisture, precipitable water over 1.00 inch, spreads to
near the Wyoming border by late Thursday.

Wednesday storm and shower coverage will increase through the day
and Wednesday night as sheared dynamics has increasing moisture to
work with. Wednesday night may be the most active period with precip
water values approaching 1.25 inches in east-central Utah along
with dynamical support. Gusty storm-produced winds may become
widespread over the southern and central zones. Boundary interaction
should keep storms going into and through Thursday.

Friday, deep moisture remains in place but upper-level forcing is
lacking so scattered storms and showers will form mainly with and
beyond afternoon heating.

Temperatures will be shaved under the clouds and showers Wednesday
through Friday, but dewpoints will climb into the mid 40s to mid
50s making for uncomfortable, mucky conditions. Evaporative
coolers will not produce much cooling.

Saturday-Monday, the ridge is flattened by energy moving through
the northern Rockies. Available moisture is pushed to the east in
a drier west flow. Daytime temperatures to be near normal.

&&

.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 557 PM MDT Mon Jun 27 2016

VFR conditions will persist across eastern Utah and western
Colorado through the next 24 hours. Isolated showers and
thunderstorms over the southern San Juan mountains will end by
03Z this evening. Tuesday, moisture will begin to increase
northward into the area. Expect scattered high-based afternoon
thunderstorms over the southern and central mountains, with
isolated thunderstorms over the adjacent lower elevations. Strong
outflow winds and localized mountain obscuration can be expected
from some storms.

&&

.FIRE WEATHER...
Issued at 330 PM MDT Mon Jun 27 2016

A moisture surge into the Four Corners will initially produce high
based thunderstorms. A dry sub-cloud layer Tuesday afternoon will
mean many if not most thunderstorms will produce dry lightning and
locally gusty outflow winds. Coordinated with the Moab Fire
District to issue a Red Flag Warning for zones 490-491 for dry
lightning from 2-8 PM MDT.

Moisture is expected to be deeper over SW Colorado but Colorado
zone 207 needs to be monitored for potential dry lightning.

The latest forecast still shows portions of Colorado zone 200 may
be close to the wind and RH criteria for critical fire weather
conditions on Tuesday. For now these conditions look to be brief
and isolated in coverage.

&&

.HYDROLOGY...
Issued at 330 PM MDT Mon Jun 27 2016

Releases from area reservoirs and management of water diversions
will likely add to flow in some rivers and streams. As a result,
waterways across the area will continue to run high, fast, and
cold through the coming weekend. Stay advised of the latest river
forecasts by visiting our website at weather.gov/gjt.

&&

.GJT Watches/Warnings/Advisories...
CO...None.
UT...Red Flag Warning from 2 PM to 8 PM MDT Tuesday for UTZ491.

&&

$$

SHORT TERM...Joe
LONG TERM...Joe
AVIATION...JRP
FIRE WEATHER...Joe
HYDROLOGY...AS



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