Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 201716
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
1216 PM CDT SAT AUG 20 2016

.UPDATE
Issued at 1216 PM CDT Sat Aug 20 2016

Threat of additional heavy rains has continued to diminish thru the
morning. Flash flood watch areas can still expect some periodic SHRA
thru the early afternoon, but rain total from here on out thru the
day looking to mostly be less than 0.10 inch. A few 1/4 inch amounts
still possible but this would not be enough to create additional
water problems. Thus the flash flood watch that was to be in effect
thru the afternoon will be canceled.

&&

.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 18Z TAFS through 18Z Sunday afternoon)
Issued at 1216 PM CDT Sat Aug 20 2016

One last band of -SHRA lifting across the TAF sites thru early this
afternoon. Continued a mention of mainly MVFR cigs with these -SHRA.
Once the band passes, mainly bkn cigs continue to lift into 3K to 5K
ft range thru the afternoon. Some NW winds 10-15kt G20-25kt thru
much of the afternoon, with these winds diminishing after 22-23z.

Generally good vfr expected tonight/Sun morning as deeper layered
subsidence behind the passing mid level trough and shortwave
continue to spread across the area. Northwest gradient winds of 5-
10kts expected to keep the boundary layer stirred and keep any BR/FG
in the 09-14z period very limited. (Will have to watch late Sun
night/early Mon morning for valley BR/FG when winds will be more
light/variable)

&&

.HYDROLOGY...Today
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...None.
MN...None.
IA...None.
&&

$$

UPDATE.......RRS
SHORT TERM...WETENKAMP
LONG TERM....WETENKAMP
AVIATION.....RRS
HYDROLOGY....WETENKAMP



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