009
FXUS63 KARX 072341
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
641 PM CDT Sat Jun 7 2025

.KEY MESSAGES...

- On and off showers and a few storms continue through Sunday.
Widespread, light showers are expected Monday.

- More rain chances could creep back in for the mid part of next
week, but still looking for some warming.

- Next weekend starting to trend dry - but a lot of
uncertainty in timing/positioning of an upper level ridge.

&&

.DISCUSSION...
Issued at 115 PM CDT Sat Jun 7 2025

* Shower/storms chances persist through the weekend with widespread,
  but mostly light showers Monday.

Weak instability, a passing shortwave to the south, and weak mostly
differential heating sfc boundaries will be enough to continue to
spark showers and a storm or two through the rest of the afternoon,
diminishing by early evening. CAMS continue to favor most of the
activity over northern IA/southern MN. Any convection that works
east into WI will run into some drier air and likely diminish in
coverage and "intensity" as a result.

Spiral of shortwave energy slides southeast across the region
tonight, preceding a closed upper level low. At the sfc, a cold
front attends the shortwave. A ribbon of 850 mb moisture transport
push northeast along the front, providing some fuel/additional lift
for convection. Some instability with the front/shortwave combo, but
fairly meager (500+ J/kg of MUCAPE) and RAP/HRRR point to rather
skinny CAPE profiles (weaker updrafts). Some shear to aid storm
development, but timing, lack of instability and overall profile
doesn`t lend to a severe risk, let alone stronger storms. All the
CAMs do convect a narrow band of showers and storms, bisecting the
local area in a NE-SW orientation at 12z Sun, exiting southeast
before noon.

Sunday isn`t done for rain chances though as instability is expected
to increase in the dry slot/clearing areas post the front for the
afternoon. The westward hanging portion of the upper level shortwave
will still be in the vicinity, while differential heating could
result in some sfc boundaries. The result could/would be a
smattering of convection for the afternoon (20-30%).

Moving into Monday the 500 mb low is still tracking to slip
southeast out of Canada and across the upper mississippi river
valley by 12z, then kicking east across the eastern great lakes
overnight. Widespread, but mostly light showers are expected for much
of the day, especially in the north and east.


* MID NEXT WEEK: what looked dry may be more "active" with shower,
  storm chances. Still trending warmer.

Quite a change in the latest EPS and GEFS runs compared to the last
several days. What looked like an upper level ridge dominated few
days of drier and warmer conditions has took a swing to the wet. WPC
clusters were showing some trends of flattening that mid week ridge,
and that continues to be favored. The main change is the bulk of the
GEFS and EPS members want to slide a west-east running shortwave
trough through the ridge, laying out a spread of QPF from southern
MN/northern IA through southern WI starting Wed night. More bits of
energy could then ride along a lingering sfc front (also orientated
west-east) through Fri. Gone are your dry days. Hello to more rain
chances. Confidence shaky in how this will all play out, but there
were hints that the upper level pattern could trend this way - and
long range guidance continues to latch onto it. Will roll with the
model blend for pcpn chances for now.

For temps, highs are still looking to push back into the 80s, but
that could be tempered by those rain chances. So, some uncertainty
with how that will unfold.


* NEXT WEEKNED-EARLY NEXT WEEK: perhaps the dry days mid week was
  suppose to deliver come next weekend. Hinting at much warmer air
  for the following week.

The upper level ridge may undergo strengthening/amplification across
the plain states for next weekend as upper level shortwave troughs
drop southward along the west coast. This stronger ridging has been
evidenced in the past few runs of the WPC clusters while EPS and
GEFS also continue to show an uptick in temps. The bulk of the heat
could hold over the plains before some break down of the ridge as
shortwave activity from the west work across it.

If this scenario comes to pass, next weekend into the start of the
following work week would lean into dry...then potentially rather
warm.

With some volatility creeping in to how the long range guidance
wants to handle the upper level pattern, not going to put too much
stock into one particular model run over another. Still, the
influence of a stronger upper level ridge to eventually work across
the region has been a consistent signal - but timing has varied. The
current model blend has a lot QPF producing members in it, and thus
are painting higher chances for Fri-Sat night (30-60%). Will hold
with that for now and see how trends lean over the next few days.

&&

.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 640 PM CDT Sat Jun 7 2025

Predominantly VFR conditions are forecast for the TAF period,
the only exception being along a transient front that passes
through the area between 09-15Z tonight/Sunday morning, where a
2-4-hour of MVFR ceilings could accompany its passage. Moving
into Sunday afternoon, scattered high-based showers/weak storms
move through the area that could conceivably bring a brief
period of MVFR visibilities. Light south winds tonight back to
the northwest behind the aforementioned front and increase to
10-15G15-25 kts in the afternoon--strongest west of the
Mississippi River.

&&

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

&&

$$

DISCUSSION...Rieck
AVIATION...Skow