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Area forecast discussion...updated 
National Weather Service Aberdeen South Dakota
1106 am CDT Friday may 22 2015

issued at 1102 am CDT Friday may 22 2015

Current forecast looks good with only some cirrus spreading in
from the south. Temperatures well on their way to the 70s for
afternoon highs.

Update issued at 654 am CDT Friday may 22 2015

See below for an updated aviation forecast discussion.


Short term...(today through Sunday afternoon)
issued at 346 am CDT Friday may 22 2015

Clouds are increasing across far southwest South Dakota this morning
as the next upper level shortwave approaches the region. Current
water vapor imagery suggests this feature is moving over northeast
New Mexico...into southern Colorado. The timing of this feature as
it progresses northward isnt completely agreed upon between models.
Either way cover should move into the southwestern
County Warning Area early this afternoon...keeping high temperatures a few degrees cooler
than the northeast County Warning Area. Winds will also be breezy across the western
half of South Dakota as the pressure gradient tightens up.

Probability of precipitation return to the forecast late tonight as the above mentioned
shortwave nears the region. While currently well defined...models do
show the forcing with this feature becoming more diffuse as it
tracks north. Additional probability of precipitation are then forecast Saturday as energy
kicks out ahead of the main upper low. There will likely be a break
in precipitation between the two...but hard to pinpoint exactly when that
may occur. Moisture does increase nicely...with a saturated column
Saturday and Sunday...and precipitable waters peaking around 1.3 inches Sunday
morning. Because several waves of energy pass over the region it is
likely there will be on and off periods of rainfall...but very hard
to pinpoint any distinct dry probability of precipitation overall are
broadbrushed. The strongest forcing/highest probability of precipitation reside in the
Saturday night/Sunday morning time frame. Overall it is a pretty
stable general thunder remains the theme.

Long term...(sunday evening through thursday)
issued at 346 am CDT Friday may 22 2015

When the period active/wet pattern is already in progress
over the region. This seems to be the general consensus amongst
longer range gsm output. By about halfway through the period...the
GFS model begins to diverge from the ec/Gem in its handling of upper
level flow pattern evolution. The European model (ecmwf) appears to have support of
the Canadian in terms of the flow pattern just reseting to west-
southwesterly with more short wave energy moving out over the region. The
GFS finally comes back around to southwesterly flow /like the other model
solutions/ aloft by day 7...including additional precipitation chances from
more transient short wave energy working through. Superblend probability of precipitation in this
active pattern are smearing the entire period with probability of precipitation...likely a
bi-product of run-to-run timing differences of all these little
transient S/ws forecast to move over the central/northern plains
states. If there was a time period when rain chances are little to
none...based off tonight's deterministic model would
likely be late Tuesday afternoon through early Wednesday evening.
The GFS/European model (ecmwf) low level thermal forecasts are not all that similar
either this go round. Will stick with superblend for this forecast
package and see if models are in any better agreement in 24 hours.


Aviation...(for the 12z tafs through 12z Saturday morning)
issued at 654 am CDT Friday may 22 2015

VFR conditions are expected at all terminals through the entire
valid taf time period. A few showers may make their way into the
kpir/Katy areas later tonight.


Abr watches/warnings/advisories...
South Dakota...none.


short term...serr
long term...dorn

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