Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Grand Junction Colorado
447 PM MDT Thursday Jul 30 2015

Short term...(tonight through Friday night)
issued at 320 PM MDT Thursday Jul 30 2015

A disturbance just south of The Four Corners is gradually shifting
north bringing better moisture and lift to extreme southeast Utah
and southwest Colorado this evening. Very slow if existent storm
motion and increasing precipitable water means there is a slight
chance for some very isolated Hydro problems but with showers and
thunderstorms not moving they will remain over higher terrain in areas
which drain better than the dry washes at Lower Valley desert
locations. A few showers and thunderstorms are expected to continue
through the overnight hours.

Moisture stays deepest over the southern edge but begins to slowly
spread northward on Friday. However it still mainly stays south of
Interstate 70. The la sals...Grand Mesa and west elks will be on
the northern edge of any storms that develop during the afternoon.
With the deepest moisture over the south...1.3+ precipitable water
at midnight at The Four Corners...a few nocturnal storms will be
possible along our southern edge overnight.

Daytime highs will be near normal...except over the far south
where better clouds/precipitation will limit afternoon heating.
Nighttime highs will not be as cool as the ridge builds over the
region and as dewpoints increase even over the far north.

Long term...(saturday through thursday)
issued at 320 PM MDT Thursday Jul 30 2015

High pressure will remain over the region through the period. The
ridge will initially stretch from Arizona/nm/TX to the Pacific
northwest through the weekend. Then in response to low pressure
developing over the Pacific northwest...the ridge will become
more south-north oriented over The Spine of The Rockies.

For the details...moisture will continue to spread into the
central portion of the forecast area on Sat...with the far north
remaining on the dry side. On sun/sun evening a disturbance will
rotate around the high from the southwest to the northeast across
our forecast area. This will push moisture to the north ahead of
it...and will enhance the diurnal showers/thunderstorms. So expect
sun to become quite active with storms finally spreading north of
the Tavaputs/Flattops. Expect some nocturnal convection to persist
before this wave finally shifts northeast of the area. Models
indicate a downturn for early in the work week...before the next
monsoonal surge begins to work into the area on Wednesday and Thursday.


Aviation...(for the 00z tafs through 00z Friday evening)
issued at 447 PM MDT Thursday Jul 30 2015

Isolated/scattered showers and storms will continue this evening and
overnight across the southern mountains and valleys potentially
impacting kdro and ktex with gusty winds and brief moderate rain.
Areas north of the abajos and San Juans will see VFR conditions
with little cloud cover tonight. Moisture will spread further
north Friday with shower and thunderstorm coverage extending into
areas along and south of the la sals...Grand Mesa and west elks
by 18z Friday through Friday evening with potential for brief
heavy rain...frequent lightning and gusty outflow winds.


Gjt watches/warnings/advisories...


Short term...jam/eh

National Weather Service Glossary of Abbreviations