627
FXUS63 KARX 141751
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
1251 PM CDT Sun Jul 14 2024

.KEY MESSAGES...

- Storms expected early this morning. Some storms will be strong
  to severe with damaging winds and locally heave rain. Large
  hail is possible.

- Another round storms expected late Sunday night into Monday.
  Some of the storms could be severe.


- Hot and muggy conditions continue today into Monday with highs
  in the upper 80s and lower 90s. Widespread heat indices of 90
  to 100.

- Cooler and drier conditions beginning Tuesday and into much of
  the upcoming week with high temperatures in the middle to
  upper 70s.

&&

.DISCUSSION...
Issued at 315 AM CDT Sun Jul 14 2024

This Morning into Tuesday

Latest water vapor satellite imagery shows several vigorous pieces
of energy embedded in the west to northwest flow aloft across the
Northern Plains States/Great Lakes Region. One piece of energy is
producing showers and storms from east central Minnesota/western
Wisconsin. This piece of energy will continue to track east with the
stronger storms associated with the piece of energy to move
southeast over western Wisconsin/southern Minnesota. There is enough
instability with around 2000 j/kg in the 100mb mixed layer CAPE and
0-3km shear is around 20 knots out ahead of the storms. Large hail
will be the main threats with these storms through early this
morning.

Piece of energy/associated convection moves east of the forecast
area this morning...subsidence behind the piece of energy should
allow a diminishing trend of convection across the forecast area mid
morning. Then concern today becomes the heat across forecast area.
Temperatures should warm into the middle 80s to around 90 degrees
this afternoon...as the latest 14.00z GFS/NAM suggest 925mb
temperatures warm to plus 22 to plus 24 degrees celsius by 18z.
Combined with dewpoints in the lower to middle 70s...heat indices
will be in the 90 to around 100 range across the forecast area.

Another piece of energy will track across the Upper Mississippi
River Valley Monday. Decent moisture convergence/vertical motion
will produce another round of convection across the forecast area.
Depending on timing of the piece of energy...some of the storms
could be severe....as the deterministic 14.00z GFS/NAM indicate 0-
3km shear of around 30 knots with instability over the area.
Plus...lingering convection from Sunday night could limit the
instability over the forecast area and inhibit severe storms. Main
threats will be damaging winds...locally heavy rain and hail.

Cooler temperatures will be on tap for Tuesday...as piece of energy
pushes east of the forecast area and upper level trough digs over
the Upper Great Lakes region. Expect temperatures to be below
normal...with highs in the 70s.

Wednesday through Saturday

Latest 14.00z GFS/ECMWF show weak upper level ridging over the
Northern Plains States through the forecast period. With subsidence
underneath upper level/surface ridge...will inhibit any
showers/storm development through much of the forecast period.
However...there is a couple of weak pieces of energy overtopping the
upper level ridge Friday night into Saturday. Weak moisture
convergence in association with the pieces of energy may produce an
isolated shower/storm. At this time...will continue with dry weather
through the forecast period. Temperatures Wednesday through Saturday
will remain near or slightly below normal...with highs in the 70s to
lower to middle 80s.

&&

.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 1240 PM CDT Sun Jul 14 2024

VFR conditions are expected to prevail through this TAF period.
There is a high-level stratus ceiling moving from west to east
into the local area from a dying thunderstorm complex early this
AM across Iowa. This remnant thunderstorm complex is expected to
bring a chance (30 to 50%) for afternoon thunderstorms along
and south of Interstate 90 this afternoon between 20 and 24Z,
but these chances are not expected to impact LSE or RST.

As the boundary layer decouples tonight, there is a 20% chance
for river valley fog to develop at LSE, but will hold off on
putting in TAF at this time due to uncertainty in development.

&&

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

&&

$$

DISCUSSION...DTJ
AVIATION...JAW