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Area forecast discussion 
National Weather Service Sioux Falls South Dakota
348 PM CDT Sat may 30 2015

Short term...(this evening through sunday)
issued at 348 PM CDT Sat may 30 2015

Quiet weather should continue for most of the area through the
latter half of the weekend. Surface ridge in central Dakotas this
afternoon will slide east across the upper Midwest into the western
Great Lakes through Sunday. Another cool night expected as surface
winds drop off to around 5 miles per hour or less this evening under mostly
clear skies. Exception will be in our western areas where winds and
middle-high level clouds will increase a bit during the latter half of
the night. Some models also hinting at low level clouds working back
into northwest Iowa as trajectory becomes easterly and draws on the
higher moisture still in place across northern Iowa. Not convinced
the high relative humidity levels seen in the models are not just a
reflection of the cool air mass moving across the region...nor that
it will lead to more than scattered will stick with
partly cloudy range cloud cover across our southeast forecast area
tonight. Anticipate lows on the cooler end of the guidance spectrum
with readings mostly in the lower 40s...though some locations in our
north/northeast may briefly dip into the upper 30s again.

Middle-high clouds will continue to expand over the forecast area on weakening middle level wave tracks east across the Dakotas.
Decent amount of isentropic lift ahead of the wave during the late
morning/afternoon...but moisture on the sparse side below the middle
level cloud deck...especially near/south of I-90. Thus have trimmed
probability of precipitation from southern parts of the area and focused just a low chance
across the north. With extensive cloud cover...relatively light east
to southeast winds and retreating cool air mass...will keep highs on
the cooler side most areas. Looking at mainly Lower-Middle 60s for the
northeast half of the forecast area...with readings climbing closer
to 70 or just above near the Missouri River valley.

Long term...(sunday night through saturday)
issued at 348 PM CDT Sat may 30 2015

A fairly weak low level jet will develop west of Interstate 29 on
Sunday night...and there may enough Theta-E advection across that
area to produce isolated showers/thunderstorms later at night. With
clouds and a moderate southeasterly wind it will be a milder night
with lows in the lower to middle 50s. Other than the possibility of
some dying showers on Monday morning the remainder of the day looks
to be dry as upper level ridging begins to build into the region.
This will result in slightly warmer temperatures with highs mainly
in the 70s. In will be somewhat breezy with mixed
layer winds running around 20 to 25 kts.

For the remainder of next week...a broad upper level ridge will
dominate across the central Continental U.S. Through the period. This will
allow for above normal temperatures through the period with highs
mostly upper 70s to lower 80s and lows upper 50s to middle 60s. It does
appear to be an unsettled period as a series of shortwaves traverse
the ridge...though confidence in timing is somewhat low with model
differences. The better chances may lie some time in the Wednesday
night to Thursday time spite of timing differences...with
models having some consensus with a stronger wave tracking through
the region during that time frame. Severe storm chances are rather
unpredictable at this spite of there being periods of
decent instability...with winds aloft not being especially
impressive for much of the period.


Aviation...(for the 18z tafs through 18z Sunday afternoon)
issued at 1226 PM CDT Sat may 30 2015

Broken MVFR stratocu ceilings at start of the period in parts of
the area expected to become scattered by middle-late afternoon as
drier low level air continues to work southward into the region.
Thereafter VFR conditions will prevail through the period. Some
models hinting at some moisture return in the 1500-3000ft layer
late tonight/early Sunday...but does not appear extensive enough
to warrant more than few-scattered mention in the tafs. Greater coverage
of middle level clouds generally above 12kft expected to overspread
the area from the west after 12z Sunday. Spotty light rain showers
could accompany the increasing clouds late in the period...but
more likely to hold off until after this taf period and have not
included any mention of rain showers through 31/18z.


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


Short term...jh

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