FXUS63 KARX 271143

Area Forecast Discussion
National Weather Service La Crosse WI
643 AM CDT Sat May 27 2017

Issued at 532 AM CDT Sat May 27 2017

Dense fog has become more widespread across northeast Iowa. Have
issued a dense fog advisory through 8 AM this morning for all
counties in northeast Iowa except Mitchell.


.SHORT TERM...(Today and tonight)
Issued at 219 AM CDT Sat May 27 2017

After some patchy dense fog early this morning, main impactful
weather concerns today will be on shower and thunderstorm chances
through early this evening. Focus then turns to precipitation
chances through Memorial Day.

Watching a couple of features today track towards the Upper
Mississippi River Valley. 1) A shortwave/MCS tracking across Iowa
through northern Illinois and 2) A trough moving across the
Dakotas and Minnesota, scheduled to arrive later tonight. A weak
frontal boundary slid across the region during the overnight and
will reside across northeast Iowa and far southwest Wisconsin by
late afternoon. 0-4 KM MUCAPE values are expected to climb into
the 500 to 900 J/kg range with 0-3 km bulk shear of around 25-30
kts. If these CAPE and shear values are realized then we may see
a strong thunderstorm or two across portions of northeast Iowa and
far southwest Wisconsin with the potential for some gusty winds
and perhaps small hail. Precipitation chances will then increase
as we go into tonight and the trough moves in. We should then see
a steadier band of rain set up across the area. While most areas
will see some rain the band will be most concentrated over
northeast Iowa into southwest and central Wisconsin.

.LONG TERM...(Sunday through Friday)
Issued at 219 AM CDT Sat May 27 2017

We should see a little break in the rain showers Sunday morning
before another trough dives into the region from the north. This
will be the start of a cooler pattern as a broad upper level low
sets up across Ontario with troughing across the entire region. We
will see breezy westerly winds on Sunday as a tight pressure
gradient sets up. Plan on more widespread rain showers on Memorial
Day as the trough and cooler air aloft settles overhead.
Thunderstorms chances will be confined to the afternoon hours on
both Sunday and Memorial Day when some weak CAPE will be in place
thanks to daytime heating. Highs on Memorial are expected to range
from the upper 50s over northern Wisconsin to the possibly the
upper 60s across northeast Iowa. There is continued low chances
for showers on Tuesday then we should see some drier conditions
Wednesday into Thursday as surface high pressure edges in from the
west. Beyond Thursday, forecast confidence tapers off so have
leaned heavily toward a model consensus blend during this


.AVIATION...(For the 12Z TAFS through 12Z Sunday morning)
Issued at 643 AM CDT Sat May 27 2017

The clouds will increase and lower this afternoon and tonight as
a series of short wave troughs move through the region. Even
though this will be the case, the ceilings will remain VFR.
Scattered showers and isolated thunderstorms will move into
southeast Minnesota and northeast Iowa this afternoon and the
spread in western Wisconsin this evening. These showers will then
increase in coverage and they will affect KLSE after 28.06z.

Visibilities will become MVFR across southwest and central
Wisconsin after 28.06z. At this time, it looks like they will stay
south and east of KLSE.


Issued at 219 AM CDT Sat May 27 2017

Elevated river levels continue along the Mississippi River with
flood warnings in effect for some areas. Continue to exercise
extreme caution if you are planning any recreational activities on
or near the Mississippi River. Be alert for debris in the water
that could be hazardous to watercraft. Continue to closely monitor
river forecasts and the latest river statements.


IA...Dense Fog Advisory until 8 AM CDT this morning for IAZ009>011-



SHORT TERM...Wetenkamp
LONG TERM...Wetenkamp
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