Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 201146

Area Forecast Discussion
National Weather Service La Crosse WI
646 AM CDT SAT AUG 20 2016

.SHORT TERM...(Today and tonight)
Issued at 350 AM CDT Sat Aug 20 2016

Main forecast concerns are on the potential for some locally heavy
rainfall today which may lead to flooding in areas already hit by
heavy rain this past week.

Surface low pressure is deepening across the forecast area this
morning as an upper trough digs into the region from the Dakotas.
Ongoing convection across sections of Wisconsin will also help to
deepen the low this morning. So, showers will become widespread this
morning and we could even see some isolated thunderstorms at
times. As the surface low lifts northeast today the heavy rain
environment will be shunted to the east of the forecast area and
we will most likely see the bulk of the rain across northwest into
sections of northern Wisconsin where the deformation zone sets up.
However, until the low starts lifting to the northeast, cannot
rule out some locally heavier rainfall at times. If this rain
would happen to fall over locations recently hit by heavier
rainfall, basically Wabasha County east through Jackson into
Adams County, we may see some areas of flooding develop. However,
the threat for flash flooding appears to be diminishing. Will hold
onto the Flash Flood Watch until the low passes and the heavier
rain environment edges into eastern sections of Wisconsin.
Rainfall amounts of 1 to locally 2 inches appears possible. Warm
cloud depths of 3.5 KM and precipitable water values hover in the
1.6 to 1.8 range and can just see a warm frontal feature near the
interstate 94 corridor across western into central Wisconsin this
morning. However 850 mb moisture transport into this areas is
weak. Showers and isolated thunderstorms will taper off this
afternoon. Showers look to linger across northern Wisconsin this
evening as the low lifts northeast over eastern Lake Superior.

.LONG TERM...(Sunday through Friday)
Issued at 350 AM CDT Sat Aug 20 2016

Surface high pressure edges in from the west on Sunday. Clouds
should gradually clear from west to east through the day, but they
may be stubborn to do so, especially across central into eastern
Wisconsin. A weak shortwave passes  across over northern
Minnesota and Lake Superior Monday night but the forecast area
should remain dry.The surface high pushes off to the east Monday
night into Tuesday as a trough edges east out of the northwest
CONUS. Southerly flow will set up across the region and it could
be rather breezy Monday afternoon and again on Tuesday. The trough
continues its eastward track Tuesday night into Wednesday dragging
a cold front across the area with chances for showers and
thunderstorms. After a slight warmup on Tuesday, with highs
edging into the lower 80s, cooler highs return for late week with
highs slipping back into the 70s. The next chance for rain looks
to arrive this weekend.


.AVIATION...(For the 12Z TAFS through 12Z Sunday morning)
Issued at 634 AM CDT Sat Aug 20 2016

A couple band of showers will move east across the TAF sites
through mid afternoon and then it will be dry for the remainder
of the period. The visibilities may be briefly become MVFR
in some of the showers. Otherwise visibilities will be VFR.

Other than a brief period of IFR/MVFR ceilings in showers...
the ceilings will be primarily in the 3 to 6K foot range today.
As high pressure builds across the region tonight, skies will
clear between 21.06z and 21.09z. Normally, this would be
conducive to fog development, but the winds look too strong
in the soundings.


Issued at 350 AM CDT Sat Aug 20 2016

Additional rainfall amounts of 1/2 to locally 2 inches are
expected today. The heaviest rain looks to fall across portions of
west central into northern Wisconsin. While it appears the threat
for flash flooding has diminished, if the axis of steadier rains
sets up across areas hit by heavier rains this week, flooding may
develop. Will continue the Flash Flood Watch with good forecast
model consensus of a heavier deformation band setting up this
morning with 1 to 2 inches of rainfall possible near or over the
Flash Flood Watch area. One hour Flash Flood Guidance in these
areas is only at 1.3 to 1.5 inches. Rainfall rates may not be high
enough for flash flooding, but significant rises are possible on
creeks and streams.


.ARX Watches/Warnings/Advisories...
WI...Flash Flood Watch through this evening for WIZ032>034-042>044.

MN...Flash Flood Watch through this evening for MNZ079.



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