Weather Service Report


071 
FXUS65 KGJT 301707
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
1107 AM MDT THU JUN 30 2016

.SHORT TERM...(Today through Friday)
Issued at 407 AM MDT Thu Jun 30 2016

Showers continued over portions of southeast Utah and southwest
Colorado early this morning as a meso-scale convective vortex
(MCV) associated with last night's storms pushed slowly to the
northeast. It seems likely that this weak perturbation will
continue to bring light to moderate rain to west-central Colorado
and portions of the San Juan mountains around sunrise.

During the latter part of the morning and through the remainder of
the day, diurnal heating of the deep monsoon moisture over the
area will become the driving force for increased shower and
thunderstorm activity. Models did a good job of forecasting
precipitable water levels Wednesday, so latest predictions calling
for 0.9 to 1.0 inch of liquid appears reasonable. Like yesterday,
higher terrain will initially be favored, but storms should move
over adjacent lower elevations during the latter part of the
afternoon and into the evening. Expect the northern reaches of the
forecast area will see increased activity relative to Wednesday as
the easterly wave discussed over the past several days sweeps
across the northern border of Utah and Colorado. Due to the depth
of moisture storms will be increasingly capable of laying down
heavy rain. Storm motion will be from the west at close to 20
knots so expect excessive rainfall will be localized. Cape and
shear indicated to be pretty minimal, so do not anticipate
organized cells, though outflow boundary interactions may result
in one or two strong cells. 

Scattered nocturnal showers and thunderstorms expected overnight
with deep monsoon moisture in place. Both GFS and ECMWF indicated
energy moving northeastward from Arizona, and eastward across
northeast Utah later tonight so coverage may be more widespread
than currently forecast across those areas. However, not confident
in timing and placement of mesoscale features this far out, so
will leave PoP values more evenly distributed for now. More of the
same expected Friday as conditions indicated to be largely
unchanged. South may be quite active if the disturbance moving
from Arizona materializes as depicted in the ECMWF.

Temperatures will continue to trend downward for the latter half
of the week in response to increased clouds and shower activity.
Latest guidance appeared reasonable so made only minor changes.

.LONG TERM...(Friday night through Wednesday)
Issued at 407 AM MDT Thu Jun 30 2016

A drier westerly flow will start to push into the central
intermountain region this weekend, with a downturn in showers
and thunderstorms expected to begin from the west on Saturday. The
drier westerly flow should persist through at least Wednesday of
next week, with a warming trend expected for max temperatures
through at least Tuesday and then will probably level off for
Wednesday.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1101 AM MDT Thu Jun 30 2016

showers and thunderstorms will continue developing and become
more widespread through 02z. Gusty winds and heavy rain showers
will be the main threats as subtropical moisture increases across
the region. Brief IFR conditions will be possible under some of
the more organized storms. Showers and thunderstorms are expected
to decrease in coverage and intensity after 02Z with impacts on
CIGS and VSBY becoming more isolated.

&&

.HYDROLOGY...
Issued at 407 AM MDT Thu Jun 30 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...None.
&&

$$

SHORT TERM...NL
LONG TERM...JRP
AVIATION...CC
HYDROLOGY...AS

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Western Regional Climate Center, wrcc@dri.edu