194
FXUS63 KARX 110820
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
320 AM CDT Thu Sep 11 2025

.KEY MESSAGES...

- Dense fog lifts by mid-morning today with a pleasant afternoon
  in store.

- A return of summertime weather as highs surge back into the
  80s for the weekend and into early next week.

- A few passing waves of showers and storms dot the forecast,
  but impacts appear to be low at this time.

&&

.DISCUSSION...
Issued at 315 AM CDT Thu Sep 11 2025

This Morning: Dense Fog Burns Off

Widespread fog developed overnight courtesy of a nearly ideal
setup--a deep light wind layer (< 5 kts up to 7 kft) and low
T/Td spreads to start the night. The only fly in the ointment
has been a patch of low stratus clouds camped out over central
Wisconsin that has made several westward incursions and caused
the fog to lift intermittently along and north of the I-94
corridor. The fog as a whole should lift and dissipate between 8
am and 10 am, with an otherwise pleasant day in store with just
some diurnal cumulus clouds--mainly east of the Mississippi
River.

Return of Summertime Warmth this Weekend!

The main story for the weekend and early next week will be the
return of summertime heat. After one more day of seasonal
temperatures today, a warm front pushes through the region
Friday morning and allows for southwesterly flow to pump warmer
air back into the region. There is a strong consensus (>80%
confidence) that highs this weekend should top out in the
mid-80s and possibly push closer to 90 in a few spots. Moving
into next week, the upper level ridge responsible for the heat
shifts off to the east and we return to a pattern of cyclonic
flow and multiple wave transits. The airmass will cool slightly
with this pattern shift, but on the whole look for continued
above average temperatures in the low to mid 80s through
midweek. Temperatures should cool back to around average
(mid-70s for highs) for the end of the week with a transition
back to northwesterly cyclonic flow.

Mostly Dry Through the Weekend

The near-term precipitation forecast is rather dry with just a
few token rain chances (20-30%) coming with the passage of a
ribbon of mid-tropospheric theta-e advection Friday evening and
then with the arrival of our first main shortwave Sunday night
into Monday. Friday`s showers will be quite elevated and have
to work through a deep dry layer (> 10kft thick), so appreciable
rainfall is not expected. Monday`s rain potential also looks
rather paltry with the trough working against the main longwave
ridge downstream. At this point, only about 10-20% of the NBM
members have rainfall amounts for Monday of over 1/4". After
Monday, the evolution of the pattern becomes tougher to nail
down as multiple PV lobes rotate through the flow--resulting in
low, broadbrushed PoPs.

&&

.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 1155 PM CDT Wed Sep 10 2025

Widespread IFR to LIFR conditions expected to grow in coverage over
southeastern MN and western into southwestern WI overnight owing
to the combination of low fog and stratus. These conditions
clear by the mid-morning resulting in VFR conditions for the
afternoon with a 3-4 kft cumulus deck towards central WI. Will
need to monitor trends for fog development early Friday morning
east of the Mississippi River. Light and variable overnight
winds become established from the southeast during the morning
at 5-10 kt.

&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...Dense Fog Advisory until 9 AM CDT this morning for WIZ017-029-
     032>034-041-042-053>055.
MN...Dense Fog Advisory until 9 AM CDT this morning for MNZ079-
     086>088-094>096.
IA...Dense Fog Advisory until 9 AM CDT this morning for IAZ009>011.

&&

$$

DISCUSSION...Skow
AVIATION...Skow