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Area forecast discussion 
National Weather Service Grand Junction Colorado
551 PM MDT sun Aug 30 2015

Short term...(tonight through Monday night)
issued at 321 PM MDT sun Aug 30 2015

The storm environment transitions quickly from dry to wet
thunderstorms this evening. Deep moisture was being pulled into
southeast Utah this afternoon. The NAM shows precipitation water values of 1.3
inches there spreading quickly into NE Utah-northwest Colorado this evening. This
evening will likely have the most thunderstorm and shower
coverage. Storm motion will be to the NE at 20-25 miles per hour for some
potential of locally strong wind gusts. Some forcing (div q
convergence) seen across NE Utah this afternoon and across northwest
Colorado late tonight for some thunderstorms continuing there
through the night. Clouds and convective winds will keep
temperatures mild overnight.

The disturbance that passed through last night should be
northeast of the area Monday morning...but the old frontal
boundary/baroclinic zone between high pressure to our southeast and low
pressure over the northwestern U.S. Will remain over the area. A few minor
impulses and jet speed maxima...as well as a bit of vertical
speed shear...will help produce isolated to scattered afternoon and
evening showers and thunderstorms Monday through Monday night.

Long term...(tuesday through sunday)
issued at 321 PM MDT sun Aug 30 2015

Midrange models show that old boundary stretching SW to NE across
the area through Wednesday as available moisture gradually decreases.
Thursday through Sunday the forecast area becomes more under the
influence of the trough strengthening over the northwestern U.S. And
moving east through the northern rockies. A strong jet will Cut
Through northwest Utah and western Wyoming...while the gradient increases across
the northwestern portion of the forecast area. Expect SW winds to increase
over northwest Colorado and NE Utah Friday and Sat. SW and central Colorado and southeast Utah will
see an uptick of showers and thunderstorms as more moisture is
drawn north. A tropical storm from the eastern Pacific may add
some moisture into the SW flow over the area beginning Friday
night.

&&

Aviation...(for the 18z tafs through 18z Monday afternoon)
issued at 321 PM MDT sun Aug 30 2015

Thunderstorms will continue through this evening and slowly
decrease overnight. There is a good chance that some storms will
move over airports across the region bringing outflow winds to 35
miles per hour or more along with a brief lowering of ceilings. Kase...kege...
kril...ktex and kmtj have a good chance for ceilings lower than ils
breakpoints for short periods through 06z. Scattered showers and
embedded thunderstorms will linger over the region overnight.
Slightly less thunderstorms development is expected Monday
afternoon.

&&

Aviation...(for the 00z tafs through 00z Monday evening)
issued at 546 PM MDT sun Aug 30 2015

Widespread showers and thunderstorms have fired this evening
across the entire County Warning Area. Main concern from these storms are gusty
winds of 30 to 40 miles per hour though small hail is also possible along
with brief heavy rain. Most ceilings remain above ils breakpoints
though the mountain taf sites may see ceilings drop below them. Convection
will continue through 03z before starting to die down. Showers and
storms will become isolated after that with chances remaining for
showers and may an odd rumble of thunder. Included tempo groups
for thunderstorms and rain for the next 3 to 4 hours for most taf sites. More
showers and storms on tap for tomorrow becoming more widespread
between 17 to 18z.

&&

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

$$

Short term...Joe/cc
long term...cirrocumulus
aviation...tgr

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