Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 210231
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
930 PM CDT Sat Jul 20 2019

.SHORT TERM...(This Evening through Sunday)
Issued at 248 PM CDT Sat Jul 20 2019

Very active stretch of weather out there today, with several rounds
of severe convection rolling through the region, with the "last"
round currently exiting to the east. Still seeing a smattering of
additional convection bubbling along a residual outflow boundary/
cold front configuration into northeast IA, and that trend may well
continue into the evening hours with decreasing surface-based
instability but plenty of elevated CAPE above the southward-sinking
boundary. Not a lot of low level jet forcing tonight, but near-term
convective allowing guidance continues to hint at us using up the
remnant instability into the evening, particularly near/south of the
frontal boundary into northeast IA and far southwest WI within an
axis of intensifying 850-700mb frontogenetic forcing as cooler air
works in from the north. Can`t rule out a heavy rain risk down into
the area as well given persistent FGEN forcing for a few hours and
high PWAT values at 2 inches with warm cloud depths an impressive
4.5km, though would like to see some type of reinforced inflow (i.e.
low level jet) to really support training convection, which appears
lacking per current guidance trends. Along the same lines but in the
realm of better news, widespread convection, clouds, and plentiful
outflow boundaries have brought an end to the excessive heat!

Thankfully, things really quiet down later tonight into Sunday, with
a much-deserved break from the active weather and heat to wrap up
the weekend. Will be watching a northern stream shortwave
progressing out of North Dakota through the afternoon, though with
any precipitation risk likely relegated to our west with the better
forcing arriving here overnight, during a lull in available
instability. As such, outside of perhaps a sprinkle, not seeing much
of any precipitation risk through Sunday night, with instead much
more comfortable temperatures and dew points providing a really nice
end to the weekend.

.LONG TERM...(Sunday Night through Saturday)
Issued at 248 PM CDT Sat Jul 20 2019

Ready for a longer stretch of quite nice mid summer weather? We`ll
deliver it through much of the coming work week. A realignment of
the overall pattern toward building western CONUS ridging and
downstream troughing, in combination with a slow-moving low level
ridge axis working south from Canada, suggests a several day stretch
of really nice conditions, featuring seasonable temperatures mainly
in the upper 70s to low 80s but notably lower humidity, along with
more comfortable overnight lows. Can`t rule out perhaps a rogue
shower at times with a few weaker shortwaves likely to ripple
through the northwest flow regime, though nothing at this time that
really stands out until perhaps later Friday or Saturday. In the
meantime, enjoy the break.

&&

.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 930 PM CDT Sat Jul 20 2019

Cigs: high/mid level clouds for the better part of tonight scatter
out for Sunday - likely going bkn again later in the day as a low
pressure system passes to the south.

WX/vsby: convection chances looks to hold south of the TAF sites
tonight-Sunday.

With saturated ground/boundary layer from today`s rains, some
decrease in high cloud overnight and light winds, pretty good fog
setup. However, drier/cooler air starting to filter in from the
north post the front, continuing overnight. Tds could outrace the T,
keeping the fog threat at bay. For now going to hold with P6sm and
monitor.

Winds: generally light/less than 10 kts from the north.

&&

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

$$

SHORT TERM...Lawrence
LONG TERM...Lawrence
AVIATION...Rieck


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