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Area forecast discussion 
National Weather Service Grand Junction Colorado
553 am MDT Monday Aug 3 2015

issued at 538 am MDT Monday Aug 3 2015

Patchy fog as formed over portions of La Plata and Archuleta
counties. Appears to be shallow and dependent on the amount of
clouds overhead. Kdro briefly went down to 1/4sm but did not last
long. Updated grids to reflect patchy fog for this area.


Short term...(today through tuesday)
issued at 355 am MDT Monday Aug 3 2015

The focus for heavy precipitation moves north today as the center
of the closed low moves to northern Utah. Short term models
indicate some good boomers developing around noon today across NE
Utah and northwest Colorado. Showers and thunderstorms will be numerous
in coverage on Monday across northeast Utah and northwest
Colorado...with the flash flood threat decreasing as the
storminess enters a less flashy region of the country. The strong
wind and hail threat will increase today due to a veering vertical
profile and increasing speed shear. The drier air on water vapor
satellite this morning also causes concern for some strong
thunderstorms as moisture is still in place...dynamical forces
will be present...and upper jet support increases.

This weather system finally moves out of Utah and Colorado tonight
leaving some breezy conditions across the Wyoming/UT/co border. High
pressure and drier air will quickly build in early Tuesday and
keep isolated afternoon tstorm development mainly to the mountain
terrain on Tuesday. Temperatures will rebound back to near normal
on Tuesday as sunshine abounds.

Long term...(tuesday night through sunday)
issued at 355 am MDT Monday Aug 3 2015

Subtropical high pressure will be centered over the southwestern Continental U.S.
With the ridge axis along the Utah/Colorado border...effectively
shutting down the monsoonal moisture tap into The Four Corners
region. A Pacific short wave moves across the central rockies
Wednesday night or Thursday morning...but has limited moisture
with the best lift north of our forecast area (maybe a storm or
two over the high country). Surface winds become breezy Wednesday

Friday through Sunday...the high pressure center shifts toward the
Southern Plains and the monsoonal moisture plume surges north through
Arizona into Utah. Middle level moisture reaches the far south by
Friday afternoon...but the deeper moisture and higher precipitable water values
arrive on Saturday. Moisture surge will be phased with an ejecting
short wave from the West Coast trough. Saturday could be an active
convective day with deep convection with some vertical shear.
Drier air may follow the short wave on Sunday and storm activity
may become less numerous.

With respect to temperatures...more sun means warmer temperatures during middle
week but around seasonal norms. Cooling trend occurs next weekend
as moisture/cloud cover increases.


Aviation...(for the 12z tafs through 12z Tuesday morning)
issued at 553 am MDT Monday Aug 3 2015

Scattered showers across NE Utah/northwest Colorado this morning will
expand by 18z with widespread showers and storms. A few cells will
be strong with small hail...gusty winds...and heavy rain showers.
The areal coverage of storms decreases farther south. Ils ceilings
will be common for mountain taf sites. Storms are expected to
dissipate quickly this evening after 02z...with skies becoming
mostly clear (skc or few-sct100) after 06z.

Patchy fog with visible below 3sm is possible at kdro until 15z this
morning. Patchy may occur again after 06z tonight for valley


Gjt watches/warnings/advisories...

short term...jam

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