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Area forecast discussion 
National Weather Service Grand Junction Colorado
332 am MDT Friday Aug 29 2014

Short term...(today through saturday)
issued at 328 am MDT Friday Aug 29 2014

An upper ridge will build over the Great Basin today placing the
forecast area within the dry northwest flow ahead of the Ridgeline. A
weak upper trough will provide minor dynamic lift today and
daytime heating will cause isolated showers and thunderstorms...
mainly over the northern and central mountains. Maximum temperatures
should warm up about 5 degrees across the board today.

Tonight and Saturday...a more progressive weather pattern will be
setting up tonight and persist through the weekend as the polar jet
dips southward. This southern migration of the jet will carve out a
broad trough across the northern rockies and plains states by Sunday
afternoon. The first open shortwave will be passing east of the area
overnight with a transitory ridge pushing through after midnight
into the morning hours on Saturday. This will bring a general
downturn in any convection that forms this afternoon. There is
however a trailing jet maximum moving over the County Warning Area in northwest flow
overnight. This often results in isolated convection firing through
the night...confidence too low at this time to keep mentionable probability of precipitation in
place at this time. 315k surfaces do show moisture from decaying tropical
system arriving ahead of the main jet tomorrow morning which will
spread at least high cloudiness The Rockies. Flow increases from the
southwest through the afternoon and will bring some breezy
conditions to the high country. Scattered showers look to develop
over the northern and eastern mountains with afternoon instability
and this handled well at this time. Temperatures will be milder overnight
with moisture arriving aloft and should warm back to above normal
for Saturday in the strong warm air advection pattern.

Long term...(saturday night through thursday)
issued at 328 am MDT Friday Aug 29 2014

Saturday night into Sunday...the strongest part of this jet will be
nosing into the Great Basin Saturday night...reforming over the
High Plains on Sunday on the upstream portion of the passing
trough aloft. The NAM/GFS handling the cyclonic curvature of this
jet a bit differently with the NAM a bit more aggressive by
forming a coupled maxima feature over northern Utah and western
Wyoming early Sunday morning. The stronger convection formed by
the associated middle level fronto ascent in turn pushes a low level
cool front through our northern County Warning Area by middle-day Sunday. This will
affect both temperatures and light rain chances and confidence low
in this will little support from other models. No changes to
Sunday at this time and will see how this plays out but again expect
afternoon storms to fire in the eastern Divide mountains.

&&

Aviation...(for the 12z tafs through 12z Saturday morning)
issued at 328 am MDT Friday Aug 29 2014

VFR conditions will prevail across the area the next 24 hours. A
weak disturbance aloft and daytime heating will cause isolated
showers and thunderstorms after 18z through about 02z causing local
mountain obscurations.

&&

Gjt watches/warnings/advisories...
Colorado...none.
Utah...none.
&&

$$

Short term...cirrocumulus
long term...15
aviation...cirrocumulus

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