Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 270719
AFDARX

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

.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
timeframe.

&&

.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1158 PM CDT Fri May 26 2017

VFR conditions continue early this morning, but as alluded to
earlier, some fog and/or stratus is expected to develop prior to
sunrise. Given some stronger winds aloft, don`t expect fog to
become dense for the LSE terminal, though there is a low end risk
for that to occur. Any fog will dissipate through 14Z, with an
increase in mid level clouds expected through the day. There is a
slight chance for a few showers to impact LSE/RST through late
afternoon and into the evening, though the greatest risk appears
to be after 06Z tonight (end of the current TAF period).


&&

.HYDROLOGY...
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.

&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&

$$

SHORT TERM...Wetenkamp
LONG TERM...Wetenkamp
AVIATION...Lawrence
HYDROLOGY...Wetenkamp



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