Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 262035

Area Forecast Discussion
National Weather Service Grand Junction CO
235 PM MDT FRI AUG 26 2016

.SHORT TERM...(This evening through Saturday night)
Issued at 235 PM MDT Fri Aug 26 2016

Water vapor satellite imagery showing an upper level trough
dropping into the Great Basin with convection firing out ahead of
it over the Wasatch and Uintas in Utah and the higher terrain over
western Colorado. This activity is expected to increase in
coverage later this afternoon into the evening as a shortwave
moves across eastern Utah and western Colorado through the early
morning hours. This shortwave shears apart overnight so coverage
may become more isolated beyond midnight with some more showery
activity lingering into the early morning hours. Main threats
with storms today will be gusty outflow winds, small hail and
brief heavy rain in the stronger cells. Expecting cooler
temperatures tonight, similar to yesterday, due to the rain cooled
air with some light snow again at the higher peaks mainly above

On Saturday, the upper level trough will split with a cutoff
closed low forming over southern California into Arizona, with
our CWA in the deformation zone between the split trough. This
will result in another active day on Saturday with storms more
numerous over the higher terrain from the Bookcliffs southward
with some valleys being impacted later in the day.

.LONG TERM...(Sunday through Friday)
Issued at 235 PM MDT Fri Aug 26 2016

Sunday into Monday, the closed low moves eastward across Arizona
and New Mexico underneath a ridge of high pressure. The upper
level winds turn more easterly across our CWA resulting in an
unfavorable flow for moisture. Precipitable Water (PW) values
lower to 0.5 inches or less. This flow however would favor the
mountains of western Colorado along the divide, so afternoon and
evening storms are expected over these mountains and some adjacent
valleys, with western areas remaining fairly dry.

Latest model runs are painting a different picture than 24 hours
ago. What appeared to be a mostly dry week is now looking wetter
as a low pressure trough deepens over the western states, pushing
the ridge of high pressure eastward over the central Plains
states. This will allow for a more favorable southerly flow of
moisture, with PW values increasing to 0.75 and above on Tuesday
and over an inch values by Thursday through the end of the week.
This plume looks to remain over us with our CWA in the favored
right entrance region of the upper level jet. Some embedded
shortwaves move through the base of the trough from time to time,
with the strongest shortwave on Thursday, coinciding with the
better push of moisture. Expect storm activity to increase through
the middle to latter half of next week.


.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 1102 AM MDT Fri Aug 26 2016

A quieter morning is on tap behind a departing system which
brought snow to much of the timberline region overnight. Isolated
to scattered storms will again develop as the afternoon progresses
but confidence not quite as high as days past on location and
timing. Hi-res models suggest kvel/kcny may have the best
probability in the first six hours as storms move off the wasatch.
Storms and showers look likely to continue into the early morning
hours. Gusty winds and lightning will remain threats with many
storms today with small hail also possible with the stronger
storms in the valleys and many areas of the high country.


.GJT Watches/Warnings/Advisories...


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