Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 100816
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
316 AM CDT Thu Aug 10 2017

.SHORT TERM...(Today and tonight)
Issued at 316 AM CDT Thu Aug 10 2017

Main forecast concerns for today are on a line of showers and
storms exiting the area later this morning, then focus turn to
redevelopment of showers and storms during the daytime hours
today.

Watching a broken line of showers and thunderstorms move across the
area early this morning.  A few storms have shown signals for some
small hail, otherwise brief downpours and winds gusts to around 30
mph have been the primary concerns. Shear is very weak across the
area and this is the reason the storms are struggling to organize.
Look for this activity to exit the area, into central and eastern
Wisconsin, in the 5 to 9 am timeframe. The main upper level wave is
driving this activity this morning, while the surface cold front
lags behind, currently approaching the Interstate 35 corridor
across south central Minnesota and north central Iowa. CAPE does
attempt to build ahead of the cold front later this morning into
early this afternoon across central Wisconsin. Also, a more broad
area of CAPE develops across much of the area as the main trough
moves in. There could be an outside chance of a stronger storm or
two over extreme southwest into central Wisconsin before the cold
front moves out. The Main threat from any stronger storms would
be isolated hail to around 1 inch and perhaps gusty winds.
Otherwise, mainly scattered showers and storms will be the rule as
the trough moves in.

Shower and storms will taper off this evening as low pressure exits
to the east and CAPE weakens with the loss of daytime heating. The
main concern for tonight will then be low clouds and perhaps areas
of drizzle.

.LONG TERM...(Friday through Wednesday)
Issued at 316 AM CDT Thu Aug 10 2017

The low clouds then look to linger into the daytime hours Friday,
and could stick around well into the afternoon hours. Looking at
forecast soundings the moisture does gradually thin out from west
to east during the afternoon into the evening hours. The clearing
trend currently in the forecast for Friday may need to be slowed,
increasing the cloud cover across much of the area, with a mostly
cloudy day possible along and east of the Mississippi River. High
pressure then builds in late Friday into Saturday with mainly
quiet weather expected. Area of fog are possible Saturday morning,
especially along river valley locations and central Wisconsin
cranberry country.

A weak shortwave moves across the region on Sunday right around the
time of peak daytime heating. Forecast models show some weak
instability develop so cannot rule out isolated showers and
perhaps a couple of thunderstorms. Will hold onto a low chance
for showers and storms Sunday into Sunday night, but confidence is
fairly low that these will actually develop. Additional slight
chances for showers continue during the day on Monday but with
high pressure building in, this timeframe may end up being dry.
Dry weather is then expected late Monday through Tuesday as
ridging builds across the region. The dry weather looks to
continue right on into Wednesday morning. Shower and thunderstorms
chances then return for late Wednesday into Thursday as another
trough moves into the Upper Mississippi River Valley.

&&

.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1151 PM CDT Wed Aug 9 2017

A line of showers and thunderstorms continues to weaken as it
approaches, but may still bring a brief period of rainfall to RST
and LSE, though with conditions still remaining VFR. A period of
clearing skies now appears probable behind the line of showers,
before diurnal cumulus develops through the late morning and
afternoon hours, beneath cooler air behind a passing cold front.
As that front passes, winds will shift westerly and then to the
northwest, averaging 10-15 mph. Into the evening, it still appears
likely that lower stratus will quickly develop just north of the
area, spreading southward into LSE and RST but likely just after
06Z.

&&

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

$$

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



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