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National Weather Service Denver/Boulder Colorado
818 PM MDT Tuesday Sep 1 2015

issued at 808 PM MDT Tuesday Sep 1 2015

Still some weak showers/storms over southern portions of
County Warning Area...mainly across park and further east over Elbert and Lincoln
counties. Given jet streak across Colorado and further showers
over western Colorado...will keep some probability of precipitation in the forecast at least
through midnight. Will make some minor adjustments based on
current trends. Given weak instability...showers on the weaker
side but still could get some gusty winds in the 30-40kt range
with stronger showers.


Short term...(this evening through wednesday)
issued at 301 PM MDT Tuesday Sep 1 2015

Scattered thunderstorms across northeast Utah and northwest
Colorado at this hour under a little area of jet related lift.
Storms have been weakening as they move east away from the
forcing. Meanwhile lots of shallow convection in the area of old
moisture...but much of this is trapped under a little capping
inversion. Expect more storms to develop in the central mountains
during the late afternoon...moving east toward the Palmer Divide
area this evening. Meanwhile the jet streak will progress
northeast...keeping storms clipping the northern mountains but
probably keeping the strongest activity further north and west.
The Denver area may wind up being in between all of this. Made a
few more minor changes to the probability of precipitation...higher in the northern
mountains and areas near the northern border in the late
afternoon/early evening downstream of the current activity.

With all the convection upstream the clouds should be slow to
clear overnight. For Wednesday there will be further drying and
warming aloft. It will be getting really marginal for convection
on the plains. Current forecast for Wednesday looks fine.

Long term...(wednesday night through tuesday)
issued at 301 PM MDT Tuesday Sep 1 2015

Thursday into Friday...a southwesterly flow aloft will be over
the northeast plains of Colorado with the building ridge over the
southern Great Plains. A surface Lee trough will be over eastern
Colorado as well. Subtropical moisture is prognosticated to increase as
it advects from Baja California and western mx into the state Thursday night and
Friday. Some of the moisture appears to be associated with a
weakening tropical system just off Baja California mx 00z Friday. At this
time...the best thunderstorms coverage will be over the mountains.
The southwesterly flow aloft will increase Friday and Saturday as
an upper trough drops out of the Pacific northwest. There still
appears to be a decent plume of middle level moisture advecting into
the mountains. Downslope and the presence of the surface trough will
limit the thunderstorms coverage over the northeast plains. Temperatures
on Friday will be close to 90. Overall the coverage will scattered over
the mountains...10-20 percent coverage over the northeast plains. Precipitable water
values will start to increase which may enhance the rain potential
with the storms. As the upper trough passes to the north of
Colorado over the will cool off a bit with the flow
becoming more west/southwesterly. As a result...less subtropical
moisture will be present by Sunday as it gets shifted more to the
south and east with temperatures closer to normal by that time as


Aviation...(for the tafs through 06z Wednesday evening)
issued at 808 PM MDT Tuesday Sep 1 2015

Showers and outflow winds have diminished for the time with
resultant winds from the south and southeast at apa/den and bit
more westerly at bjc. Still some showers over Park County which
may eventually shoot out additional outflow over terminals as
winds may shift a bit more southwest with time.


Bou watches/warnings/advisories...


short term...gimmestad
long term...Cooper

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