864 FXUS63 KARX 111730 AFDARXArea Forecast Discussion National Weather Service La Crosse WI 1230 PM 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.
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.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.
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.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/... Issued at 1231 PM CDT Thu Sep 11 2025
With the soundings indicating less of a threat of fog (mainly due to the stronger winds aloft) removed the mention of fog at KLSE for tonight. Otherwise, VFR visibilities and ceilings are expected across the area.
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.ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None.
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DISCUSSION...Skow AVIATION...Boyne
NWS ARX Office Area Forecast Discussion