653
FXUS63 KARX 101837
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
130 PM CDT Thu Jul 10 2025

.KEY MESSAGES...

- Light showers persist into early evening. Storm potential on the
southern periphery of the rain/cloud for late afternoon/ evening (20-
40%). Widespread rain and a few storms more likely overnight into
Friday morning, but generally south of I-90. Locally heavy rain
possible.

- Friday rain chances could be confined to just the morning hours as
placement, evolution of the complex mix of weather variables trend
toward holding most of the storm chances south/southeast and farther
west.

- Trending cooler by the middle part of next week with below
normal highs in the 70s.

&&

.DISCUSSION...
Issued at 130 PM CDT Thu Jul 10 2025

> THiS AFTERNOON-EARLY EVENING: persistent light showers. Scattered
storm potential for northeast IA/southwest WI into early evening.

MCV spawned by overnight/early morning convection was churning over
southeast MN early this afternoon, continuing to pinwheel areas of
light rain around it. The clouds/showers will persist moving through
the rest of the afternoon - knocking off several degrees from
expected high temps and also working against the storm potential for
later afternoon/evening. Without much sun/daytime heating,
instability is being held in check.

If the cloud mass continues to rotate/move per latest satellite
trends, might get enough late day clearing over southern fringes -
including northeast IA/southwest WI - to increase instability and
the convective threat. Otherwise, the convective chances won`t
increase until later into the night when the low level jet kicks and
shortwave tracks in from the west.


> REST OF TONIGHT-SATURDAY: periods of showers with locally heavy
rain, Storm chances - a few could be strong, but higher severe risk
lies farther south.

Shortwave trough still on track to move out of the southern rockies,
spinning east across IA overnight, likely riding the WI/IL border
Fri as it exits across the western Great Lakes. The evening
rain/storms will likely result in a west to east sfc front lying
across IA - where this shortwave can interact with. In addition,
short term guidance increase the low level moisture into the
boundary, but mostly parallel to it (limiting additional lift).

While what happens for the rest of this afternoon/evening will have
an impact on setup for later tonight into Friday, the CAMS models
showing pretty good agreement on developing another round of
convection with the incoming shortwave, aligning along the front and
the stream of low level moisture. PWs near 2" and warm cloud depths
or 4-4.5 kft still favorable for heavy rain. If storms can repeat
over a location, localized flooding (likely mostly urban and small
streams) could/would become a concern.

If this scenario holds true, resulting outflow/rain cooled region
will further push the west-east running sfc boundary
south/southeast. While pcpn is likely to be lingering in the morning
across mostly southern parts of the forecast area, the focus for
afternoon/evening storms (and accompanying severe risk) would be
along the front - and south of the local area.

Another shortwave trough, this dropping southeast out of southern
Canada, will be sliding over the northern plains Fri afternoon,
swinging its axis across the upper Mississippi river valley Sat
afternoon. A sfc cold front will precede the trough, and it`s along
this boundary that convection is favored to fire by mid/later
afternoon. Ribbon of instability to work with but the bulk of the
deep wind shear holds westward. Current timing would bring the line
toward southeast MN well after 00z Sat. With decreasing instability
trend would be downscaling the convection both in intensity and
areal coverage. A few CAMS suggest it could diminish completely
before working into western parts of the forecast area.

Rain chances will persist Sat morning until that trough axis moves
east, The instability is shifting into eastern WI though, taking
with it much of the storm risk.


> NEXT WEEK: rain chances Tue into Wed. Turning cooler (below
normal) by mid week, potentially hanging around through the weekend.

GEFS and EPS remain in good agreement with driving a shortwave
trough/cold front out of Canada and across the region in the Tue/Wed
time frame. The bulk of both ensembles` members lay down some QPF.

Much cooler air will flow in post the front - 850 mb temps currently
progged to drop from 20 C at 00z Wed to 8 C by 18z Fri. 75% of the
GEFS and EPS members drop highs back into the 70s, but the lower 25%
of the suites suggest highs won`t warm out of the 60s on a few days.
Quite a change to the string of warm, humid summer days - if the
scenario holds true.

&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 1233 PM CDT Thu Jul 10 2025

Ongoing showers as of issuance time should continue to affect
LSE/RST and much of the region over the next 6-9 hours. A few
thunderstorms could develop within this area of showers, mainly
along and east of the Mississippi, this afternoon, although
confidence this will be borne out is low. Given the low confidence,
have included a PROB30 group for TSRA in the LSE TAF later this
afternoon rather than a TEMPO or definite mention. As trends are
monitored this afternoon, an amendment to either remove the TS
entirely or go to a better defined mention will likely be issued.
Moving ahead to tonight, trends have increasingly pointed toward
MVFR ceilings so have introduced these with this issuance. Given
amount of moisture in the atmosphere, will need to closely monitor
for IFR ceilings and/or fog for inclusion in later issuances.

&&

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

&&

$$

DISCUSSION...Rieck
AVIATION...Ferguson