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Area forecast discussion 
National Weather Service Grand Junction Colorado
1058 PM MDT Thursday may 28 2015

issued at 1058 PM MDT Thursday may 28 2015

Most convection has died off this evening. However a few showers
will continue to track across the forecast area during the next
few hours...with isolated thunder possible. One area of showers
still upstream over southern Utah has been seen on the kicx radar
loop. Expect that these showers will weaken as they track eastward
across the area late tonight. Have adjusted grids accordingly.


Short term...(tonight through Friday night)
issued at 251 PM MDT Thursday may 28 2015

Upper low spinning over western Wyoming is adding strong ascent over
our western County Warning Area. The upper jet rounding the base of this low is
accentuating the lift as the exit region noses into western
Colorado. Storms are quite strong in a similar region as yesterday
and expect these storms will be capable of strong outflow winds
and some larger hail through the early evening hours. As the jet
continues to dig southward late this evening convection should be
enhanced to the south with added instability coming from the
potential vorticity lobe rotating through with the jet. Through
the early morning hours things will be settling down in the south
as the jet shifts east of The Rockies. Up north cold advection and
energy in the back side of the low...which is settling east of The
Divide...should keep some isolated showers going over the northern
mountains back toward the Craig area. Temperatures similar to
yesterday with some light snow possible over the higher
peaks...passes will not be impacted.

Friday...the trough continues to work into the Central Plains.
Some weak forcing persists over northwest Colorado where storms will be
favored. There is enough residual moisture to fire convective
storms over all the northern and central mountains. More sunshine
over the south will begin the warming trend there.

Friday night...showers will end before sunset. Skies will clear as
a ridge amplifies over the western Great Basin. Temperatures will
be at or near normal for the final time for the next week at

Long term...(saturday through thursday)
issued at 251 PM MDT Thursday may 28 2015

A fast transition occurs this weekend from stormy and cool to
drier and much warmer. The large scale pattern is amplified and
slowly progressive. A ridge dominates through Monday with a trough
developing after Tuesday.

The ridge builds over the region by Sunday. Saturday will be the
warmest day of 2015 so far and Sunday-Monday will be another 5
degrees warmer. Lingering moisture and strong afternoon heating
could produce isolated-scattered storms over the mountains. The
valleys are expected to stay mostly dry.

Monday the ridge axis is pushed east and flattened as the next
Pacific trough makes landfall in Washington-Oregon. SW gradient
winds and high clouds increase. Temperatures remain similar to
very warm Sunday.

Tuesday the trough moves into the northern rockies and deepens
into the Great Basin. An associated weak cool front passes Tuesday
night for a slight cool down across the north. Moisture looks
very limited.

Wednesday-Thursday the trough deepens over the intermountain west.
SW gradient winds continue breezy conditions. Temperatures remain
above normal. Limited moisture may produce showers and storms
mainly over the northern mountains. The first tropical low of the
season that has been developing off the Mexican West Coast looks
to head west and not be a factor for our weather next week.


Aviation...(for the 06z tafs through 06z Friday night)
issued at 1058 PM MDT Thursday may 28 2015

Most showers and thunderstorms have diminished late this evening.
However a few showers will continue to track across the forecast
area through the early morning hours. One area of showers will
move into southeast Utah by around 06z. These showers are expected
to weaken as they move eastward...before exiting the area after
09z-10z. Showers will typically be on the light side...but may
briefly obscure mountains. An embedded thunderstorm cannot be
ruled out. Isolated showers are also possible across other
portions of the forecast area. Look for a downturn in showers and
thunderstorms on Friday...with the northern and central Colorado
mountains favored.


Gjt watches/warnings/advisories...

short term...15/Joe
long term...Joe

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