Area Forecast Discussion
Issued by NWS Des Moines, IA

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FXUS63 KDMX 280811

National Weather Service Des Moines IA
311 AM CDT Fri Oct 28 2016

.SHORT TERM.../Today/
Issued at 310 AM CDT Fri Oct 28 2016

The primary sensible weather concerns today will be temperatures and
winds. A short wave, associated forcing and surface low pressure
reflection will ride the nose of the jet across the northern Plains
into the Great Lakes by 00z. Warm advection will be fairly strong
through the morning until the thermal ridge reaches Iowa by early
afternoon, but this lift will be moisture starved with only mid and
high level cloudiness.  The 07z surface analysis shows low level
moisture has returned to eastern KS with stratus and fog development
and most high resolution models suggest this will reach southern and
possibly central IA before dissipating and lifting by noontime.

The 07z analysis also shows a warm front NNW-SSE across Iowa,
roughly from Spencer through Des Moines to Keokuk. This should lift
north and east through the state as the surface low reaches
northwest MN by 18z bringing much of the forecast area into the warm
sector. This will boost highs well through the 70s in most areas,
and possibly touching 80 in spots from Des Moines toward the MO
River. This will be quite warm but still several degrees off
records. Mixing to reach these levels would suggest a depth to
around 600m with soundings showing a brief period of wind gusts to
35 mph or more. Confidence in both temps and wind gusts is only
medium however as the NAM is less aggressive with mixing due to
effects from low level moisture, while recent HRRR and RAP runs
suggest even higher. Thus have raised wind gusts this afternoon, but
this will need to be monitored as it could go in either direction.

.LONG TERM.../Tonight through Thursday/
Issued at 310 AM CDT Fri Oct 28 2016

Tonight through Tuesday...Confidence Medium to High...Few changes
expected in the near term through Tuesday. Cool front expected to
move south into north central Iowa overnight tonight and
temporarily take unseasonably warm air with it for the moment
across the north. Tomorrow...per previous discussions an area of
precipitation will develop well behind the boundary over Wyoming
then moving east toward Iowa by late Saturday afternoon and
evening. This is associated with both an upper H850 to H700
boundary as well as a short wave over Idaho /Montana at 06z
Friday. This will result in sufficient lift to produce an area of
light rain that will translate east southeast into northern Iowa
to eastern Iowa by 12z Sunday. Over the past several days the
NAM/GFS have come around to the Euro solution of slowing the cool
front down enough that from about the I80 corridor south
temperatures will recover enough to bring a warm day to much of
southern Iowa...but not quite as warm as today. High pressure will
 settle across the region on Sunday with pleasant afternoon
conditions...and more fall like readings in the 50s and 60s. With
the active weather pattern continuing over the CONUS...another
vigorous system will be hitting the west Coast. Aloft a western
H500 mb trough will induce ridging over the Rockies and
Plains...lifting heights and thickness values. By Monday lee side
troughing will quickly result in another surface low over the
western Dakotas. This will keep a warm front and precipitation
well north of Iowa... leaving us in the warm sector. Another warm
and breezy day is expected...with high confidence again that
Monday will see highs well into the 70s. Once the Monday system
passes east...temperatures will again cool off into Tuesday. The
cool front is expected to stall south of the state and become
stationary by Tuesday evening.

Tuesday Night through Thursday...Confidence Medium...Models
coming into better agreement with regard to return flow and
potential for showers and elevated convection overnight Tuesday
night into Wednesday. This will be along a boundary that will
again move southeast of the area as low pressure tracks northeast.
 The chances for convection will continue into Wednesday along the
 receding boundary finally exiting by Thursday morning as high
pressure builds across the state. A return of cooler temperatures
will accompany the front.


.AVIATION.../For the 06Z TAFS through 06Z Friday night/
Issued at 1150 PM CDT Thu Oct 27 2016

VFR cigs expected through the forecast period for the most part.
There is some potential for patchy fog but mixing should be strong
enough that vsbys will not drop much.  There is also some hint that
stratus will move back in but confidence is low that anything more
than a sct low deck will develop.  Warm advection moves in on Friday
setting up a strong inversion but winds in this shallow mixed layer
are 25 to 40 kts so it will become windy in the late




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