219
FXUS63 KARX 091949
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
249 PM CDT Sun Jun 9 2024

.KEY MESSAGES...

- Cooler tonight with below normal lows generally in the upper
  30s to 40s.

- Showers/storm chances increase on Tuesday with periodic storm
  chances into the weekend. Details on the severe weather
  potential or any heavy rain chances will need to be worked out
  in the coming days.

- Below normal for Monday/Tuesday, but a warming trend into the
  weekend with temperatures trending normal to above normal
  with highs in the 80s.

&&

.DISCUSSION...
Issued at 245 PM CDT Sun Jun 9 2024

Tonight - Monday:

A nice Sunday so far with plenty of sunshine for most to start the
day. However, current satellite imagery shows clouds increasing
across parts of the area this afternoon with a shortwave dropping
down across the region. Model guidance has continued to keep a dry
forecast for most with some very light echos/accumulations mainly
north of the forecast area. Perhaps some sprinkles could be squeaked
out further south, but overall have maintained the dry forecast for
most across the forecast area today. Otherwise, observations so far
this early afternoon show quite breezy conditions with winds gusting
generally 25 to 45 mph. These increased northwest winds will
continue through the afternoon before relaxing into the
evening/overnight hours. Surface high pressure will begin to build
in towards the region with skies forecast to begin clearing a bit
and winds becoming lighter tonight. With this, overnight lows look
to be cooler than normal for this time of the year, with lows
forecast to drop into the upper 30s to lower 40s across portions of
central/north-central WI and upper 40s to 50 elsewhere. Drier
conditions look to follow into the day on Monday with highs rising
into the low to mid 70s for most.

Off and on precipitation chances into the weekend. Details on
the severe weather potential or any heavy rain chances will need
to be worked out in the coming days:

Monday night, surface high pressure remains over the local area with
a ridge aloft.  This ridging is broken down by a 500mb trough
tracking across Canada into the Northern Plains and eventually the
Upper Mississippi Valley/the forecast area Tuesday. Moisture
transport increases with temperatures warming through the 70s. There
is pooling of 850mb moisture ahead of the 850mb warm front and ahead
of the 850mb cold front.  Through 12Z Tuesday, the HRRR has
scattered showers/thunderstorms to the west of the forecast area
with MUCAPE and some shear over western MN.  Surface dewpoints are
progged to be quite dry, in the 40s with pooled 60s dewpoints over
western MN into southeast SD. The NAEFs precipitable watter
values have negative anomalies until 18Z Tuesday. During the
day, the vertical motion appears to lead with the trough, so
there is limited/a more gradual wind shift with less convergence
during the afternoon when there is more instability and more
shear to work with. Forecast soundings show some steep lapse
rates to work with. Hodographs show good low level shear, but
some weakness above that layer, then stronger winds/straightline
hodograph aloft. So...severe weather ingredients are not
aligned. Even so,with it being June and a warm front/cold front
moving through have kept chance pops in and will need to monitor
how these factors come together as we get closer to Tuesday.

Return flow sets up quickly for Wednesday across the Plains with a
couple of shortwave troughs embedded in the flow across southern
Canada affecting the forecast area through potentially Thursday or
Friday. Scattered thunderstorms are forecast to develop with these
features Wednesday.  The current theta-e axis is forecast across
parts of western MN/western IA with steeper lapse rates and stronger
deep layer shear in this area. This area to our west is currently
highlighted for a 15% risk of severe weather.  The embedded trough
for Wednesday into Thursday appears to have deeper moisture with
with precipitable water values near 2 inches with potentially a
stalled frontal boundary.  Should the boundary get pushed south,
more of the severe weather/heavy rain potential would push farther
south across the southern half of Iowa, but could also clip parts of
our Iowa/southern Wisconsin counties.

Ridging builds in for Friday, however a closed low over the
Southwest U.S. late in the week is forecast to head through the
Four- Corners region and lead trough energy also moves out of
the Pacific Northwest, moving through the Upper Midwest Saturday
night and Sunday. Needless to say...this storm system will bear
watching as well.

Seasonal high temperatures are in the lower 80s, thus still below
normal for Tuesday, but 80s are forecast for the rest of the
week.

&&

.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 111 PM CDT Sun Jun 9 2024

VFR conditions are forecast to continue through the TAF period,
with some increase in clouds across parts of the area this
afternoon/evening. The main TAF concern though looks to revolve
around increased northwest winds with wind gusts 20 to 35+ kts
this afternoon. Winds are forecast to decrease into the evening
and overnight hours with winds turning generally more north
tonight into early Monday.

&&

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

&&

$$

DISCUSSION...EMS/Zapotocny
AVIATION...EMS