Area Forecast Discussion
Issued by NWS Grand Junction, CO

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589
FXUS65 KGJT 231805
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
1205 PM MDT FRI SEP 23 2016

.SHORT TERM...(Tonight through Saturday night)
Issued at 141 AM MDT Fri Sep 23 2016

The current IR satellite image is showing a band of cold cloud
tops associated with a cold front passing just east of the Utah
Colorado border this morning. These cold cloud tops represent a
band of showers and thunderstorms that are at this hour producing
moderate to heavy rainfall over the Grand Junction area. So far
the cold front has been producing rain rates of 0.15 to 0.25
inches of rain per hour. The current satellite water vapor image
is showing the cold front`s parent low centered over Southeastern
Nevada.

The 0000Z NAM12, GFS20 and ECMWF have initialized well with this
low pressure system and remain in very good agreement through
Saturday night. All three models track the parent low northeast
across Utah with the center skirting Northwestern Colorado this
afternoon. With this in mind expect showers and thunderstorms to
linger around the area through tonight.

As the low continues to slide to the northeast 700mb temperatures
drop down to the upper 20s across the Western Slope of the
Rockies. These freezing temperatures will drop the snow level down
to between 7500 and 8500 feet tonight into early Saturday morning.
This will result in to 1 to 3.5 inches of snow accumulation across
the Elkhead, Park and Gore range area tonight into Saturday
morning. This early snow fall could result in an early season
Winter Weather Advisory. At this point will let this decision up
to the day shift as updated model runs come in. One more potential
impact of the cold air will be the potential for freezing
temperatures in the Upper Gunnison River Valley, The Animas River
Basin and San Juan River Basin.

.LONG TERM...(Saturday through Thursday)
Issued at 351 PM MDT Thu Sep 22 2016

Unsettled conditions will persist into Saturday as general
troughiness remains over the central Rockies. The trough axis is
progged to shift east of the Divide in the afternoon for a
downturn in activity. Temperatures will remain well below normal
for this time of year.

A drying and warming trend will get underway on Sunday as the low
moves into the northern plains and high pressure develops along
the California coast. Dry and warmer conditions will then persist
through the remainder of the forecast period as the large scale
pattern slowly evolves. Near, to a little above normal
temperatures may develop by midweek. With time, the low will shift
into the Great Lakes region as the high pressure ridge weakens
somewhat as it moves eastward over our area. By midweek models
indicate another tropical disturbance moving north along the Baja
Peninsula and a low pressure system developing over the Pacific
Northwest. If these come together, we could see another round of
wet weather, but if this verifies it will be beyond the 7-day
long term period.

&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 1205 PM MDT Fri Sep 23 2016

A strong Pacific Storm will continue to drive its associated cold
front across the area during the day. As a result, expect
widespread rain and snow to continue along and east of a KCEZ-40W
KCAG line. The snow level will be around 9000 feet resulting in
widespread mountain obscuration and low cigs. TAF sites east of
the line will experience periods of MVFR visibility and CIGS will
fall below ILS breakpoints at times.

The front finally moves east this evening with conditions improving
to VFR, though scattered snow showers will continue over the
mountains. However, after midnight fog formation may bring IFR
VSBY and CIGS.

&&

.GJT Watches/Warnings/Advisories...

CO...None.
UT...None.

&&

$$

SHORT TERM...Larry
LONG TERM...EH
AVIATION...NL



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