650 FXUS63 KARX 192258 AFDARXArea Forecast Discussion National Weather Service La Crosse WI 558 PM CDT Fri Sep 19 2025
.KEY MESSAGES...
- Scattered showers and thunderstorms through the weekend with localized heavy rain at times. Rainfall amounts through the weekend generally in the 0.3 to 0.6" range for areas south of I-94 and 0.6 to 1.25" for areas to the north of I-94.
- Temperatures stay near normal with highs in the low to mid 70s through much of next week.
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.DISCUSSION... Issued at 137 PM CDT Fri Sep 19 2025
Periodic Showers and Storms Through the Weekend:
The upper level low is finally shifting east gradually. As this low moves eastward, RAP 700mb vorticity shows impulses of shortwave energy pass through the region with the better waves moving through later this afternoon and evening and again on Saturday afternoon and evening. These are the times when the highest chances for showers and thunderstorms are likely to occur. Outside of when the more defined waves move through, there will still enough lift and instability for scattered showers and storms to occur. There are some models that hint at another wave moving through Sunday evening that could increase widespread rain chances, however exact location and strength of this wave as well as any dry air entraining in, is still uncertain as this will play a role in how high the rain chances get.
Rainfall amounts through the weekend are generally in the 0.3 to 0.6" range for locations south of I-94 and 0.6 to 1.25" for areas to the north of I-94. The HREF LPMM for 24 and 48 hours also highlights the I-94 corridor for the potential to see up to 2 to 2.5 inches by Sunday afternoon. While most of this rain will not fall all at once, with PWATs generally in the 1 to 1.4" range, there will be times when localized heavy rainfall will be possible when a heavier shower or thunderstorm moves over.
Rain Potential Next Week:
By Monday, we are still in close enough proximity to the low that another shortwave passes through increasing rain chances. At the same time, another trough dips down into the central CONUS. This trough eventually may close off and a closed low sits over the Mid Mississippi River Valley into next weekend. There are still some discrepancies in exact location and strength of the close low, as well as how long it lingers near our forecast area. Current ensemble guidance has a 60% chance that this low closes off and sits over the Mid Mississippi River Valley Region into next weekend. The other 40% of ensembles differ on location of the trough and not having the trough stem away from the parent longwave trough. Regardless if the trough does close off and form a low, lingering rain chances may continue through much of next week. Compared to previous forecasts, this trough has dug a little further south lowering our rain chances for next week. This is will be something to watch as we get closer to see how our rain chances change. Something that is of higher confidence is the temperature forecast. With the trough moving down next week and the influence from the current low overhead, highs will mostly stay in the low to mid 70s into next weekend.
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.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/... Issued at 557 PM CDT Fri Sep 19 2025
VFR conditions currently present across the area. Two corridors of showers and storms continue across the area: one stretching from Red Wing, MN to Oelwein, IA and the other across West Central Wisconsin north of the warm front. So far, the latter corridor has been the most impressive with more ample instability and a few reports of severe hail. Showers and storms are expected to continue to move east/northeast through the evening and into the overnight hours, generally on a downward trend in intensity after sunset. Fog/mist is expected to build in across much of the area overnight and into tomorrow morning, with the lowest visibilities generally along and east of the Mississippi across SW Wisconsin. Along with MVFR/LIFR CIGs, visibilities will also drop at LSE with impacts lasting into at least mid-morning. Conditions will gradually improve through the morning hours. Chances for rain return for the terminals by tomorrow afternoon, mainly after 18Z and continuing through the end of the period.
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.ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None.
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DISCUSSION...Cecava AVIATION...Barendse
NWS ARX Office Area Forecast Discussion