126
FXUS63 KARX 142019
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
319 PM CDT Wed Aug 14 2024

.KEY MESSAGES...

- From Tonight into Thursday morning, there will be a round of
  showers and storms. Some of these could produce heavy rain.

- From Thursday afternoon into Thursday evening there will be an
  additional round of showers and thunderstorms. While rain
  rates look to be less, there could be some strong to severe
  storms. This is highly dependent upon afternoon cloud cover.

&&

.DISCUSSION...
Issued at 319 PM CDT Wed Aug 14 2024

Tonight through Thursday night...

The 14.12z models continue to show that a low pressure system
will move slowly east northeast through the area and gradually
deepen. Even though it will be deepening, the 0-6 km shear is
rather messy. This is especially the case in the 3-6 km shear.
The 0-3 km shear look a bit better, but its shear is in the
20 to 30 knot range. Unlike yesterday, there appears to be a bit
more instability in the wake of the morning convection. Many of
the models are suggesting 1-2K J/kg 0-1 km CAPES. There are
even a few models up to 2500 J/kg. This will all depend on
the cloud cover during the afternoon. In addition, there will be
some moderate to steep mid-level lapse rates. This could result
in some pulse severe storms, so the marginal Day 2 SPC outlook
looks reasonable.

With precipitable water values increasing to around 2 inches
and warm cloud depths of 3.5 to 4 km, these showers and storms
will be highly efficient rain producers. WPC has the area under
marginal risk for excessive rain. It continues to look like most
areas will see anywhere from 0.75 to 1.5 inches of rain. The
24-hour HREF QPF ensemble localized probability matched mean
has an area of 2-3 inches from northeast Iowa northeast into
north-central Wisconsin.

Friday...

The 14.12z models continue to show that surface low will
continue to move east northeast into the northern Great Lakes.
This will keep scattered showers and maybe a few storms as
shortwaves rotate around this low. With limited instability and
the best moisture to our east, rainfall totals still look to be
on the lighter side.


Days 8 to 14 (August 22-28)...

Unlike the past several days, it looks like there will be a far
less amplified 500 mb pattern across the northern United States
and the Canadian Prairies. As a result, it is looking like the
omega high in the 6 to 10 day period will quickly flatten as a
series of shortwave troughs move through this region.

Northwesterly flow aloft will bring unseasonably cool air south
into the region. As a result, the chances for below-normal
temperatures have increased across the Upper Mississippi River
Valley east into the Great Lakes. While the temperatures look a
bit cooler, there continues to be enhanced chances for drier
than normal.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 1243 PM CDT Wed Aug 14 2024

Based on radar trends and CAMS delayed the onset of the rain for
this afternoon at KRST and evening at KLSE. As the rain moves
into the area, soundings show a gradual drop in ceilings to
IFR/MVFR tonight. Even added some MVFR visibilities due to fog
for KRST from late tonight into mid-morning Thursday.

Winds will be sustained around 10 knots with some gusts up to
20 knots from tonight into Thursday morning.

&&

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

&&

$$

DISCUSSION...Boyne
AVIATION...Boyne