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Area forecast discussion 
National Weather Service Pueblo Colorado
1121 PM MDT Tuesday Aug 19 2014

Short term...(this evening through wednesday)
issued at 249 PM MDT Tuesday Aug 19 2014

WV satellite imagery today showing the monsoon moisture plume over
Utah...but slowly shifting eastward as an upper low moves southward
along the California coast. Scattered showers and thunderstorms are expected this
evening over the mountains and upper Arkansas River valleys...with isolated
activity over the southeastern plains. By 03z the hrrr and rap show little if
any precipitation over the southeastern plains...with just some isolated precipitation over the mountain
areas. Overnight that upper low will move over Southern California and the monsoon
plume shifts into western Colorado. As a weather disturbance the moisture lifts
northeastward across northwestern Colorado...some precipitation will probably continue through the
night along the Continental Divide...especially over the central Colorado mountains which
will be closest to the disturbance and better moisture.

On Wednesday the upper low is expected to remain over Southern California. The best moisture
GOES north of the area with that disturbance...and models are mainly
showing spotty precipitation for the forecast area. Will keep scattered probability of precipitation over
the mountains areas for Wednesday afternoon and isolated probability of precipitation over the San Luis
valley and I-25 corridor. High temperatures on Wednesday should generally be
around to a little above average.

Long term...(wednesday night through tuesday)
issued at 249 PM MDT Tuesday Aug 19 2014

The upper level pattern is forecast to feature a broad upper level
trough over the northwest to north-central Continental U.S. And a high
pressure center over the southeast states. This will put southern
Colorado under southwesterly flow for much of the extended. There
are model differences in how they want to handle upper level
disturbances in the flow...and ensembles develop high spreads by
this weekend leading to lower confidence in the last couple of
days of the extended period.

The GFS has remained consistent from run to run with an upper
level low over Southern California and ejecting it northeast
across Colorado on Thursday night into Friday. The latest European model (ecmwf) is
more in line with this solution...however is about 24 hours slower
in ejecting the system out. The biggest forecast change for the
GFS is where the system develops convection on Thursday.

Expect ongoing convection across the mountains Wednesday evening
with models bringing band east across the plains through the
overnight hours as a weak disturbance lifts northeast. By Thursday
morning...the low pressure center over Southern California is
forecast to open up and lift northeast across Colorado.
Thunderstorms are forecast to develop over the mountains by late
Thursday morning. Thunderstorms development is then expected
eastward across the Palmer Divide through the afternoon and
evening hours. The previous run of the GFS had this thunderstorm
development further south over southern Colorado...so where this
disturbance ejects will play a role in what areas seen the
potential for heavier precipitation. The European model (ecmwf) and NAM solutions
are a bit slower with this system...with it ejecting across
southern Colorado on Friday afternoon. If this is the
case...thursdays convection will likely remain tied to the terrain
and Palmer Divide...with not much expected on the plains. The
heavy precipitation chances would then focus on Friday afternoon
and night...with heavy rainfall and the potential for flash
flooding. The important thing to remember...is that some time
between Thursday and Friday night...southern Colorado will likely
see a period of widespread heavier rainfall.

A broad tough is forecast to remain entrenched across the Pacific
northwest into the northern plains Saturday through Tuesday. The
main forecast issue will be how deep the trough gets. The GFS
solutions digs it the furthest south...with continued active
weather across the area...while the European model (ecmwf) is keep most of the
energy confined to our north with less chances for precipitation.
A cold front is forecast to drop south across the plains on Sunday
which may be the best opportunity for widespread precipitation
across the area. Otherwise...convection will likely remain over
the mountains with limited activity over the plains. Mozley

&&

Aviation...(for the 06z tafs through 06z Wednesday night)
issued at 1121 PM MDT Tuesday Aug 19 2014

Mainly VFR conditions expected at cos...pub and als over the next
24 hours...with isolated to scattered afternoon and evening showers
and thunderstorms remaining in the forecast. Best coverage of storms
to remain over and near the higher terrain and will keep thunderstorms in the vicinity after
20z in tafs at this time. Gusty winds to 45 miles per hour and brief moderate
to heavy rainfall will be possible with storms.

&&

Pub watches/warnings/advisories...
none.
&&

$$

Short term...28
long term...mozley
aviation...mw

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