597 FXUS63 KARX 081657 AFDARXArea Forecast Discussion National Weather Service La Crosse WI 1155 AM CDT Mon Sep 8 2025
.KEY MESSAGES...
- Mostly dry, return to near seasonable with daytime highs in the 70s for most today.
- Precipitation chances graze northwestern peripheral counties in southeast Minnesota and central Wisconsin overnight. Moderate precipitation chances through Tuesday (20-60%).
- Warming through the week with above normal temperatures expected this weekend.
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.DISCUSSION... Issued at 240 AM CDT Mon Sep 8 2025
Warmer, Mostly Dry Through Today:
The weekend`s surface high pressure has been shifting east through the Ohio River Valley to southern Great Lakes on early morning satellite imagery, allowing return flow to build through the Missouri River Valley. Central Plains VWPs (ICT,TOP,GID,OAX) exhibited amplification of the nocturnal low level jet, advecting a plume of higher moisture, bringing more moisture to the Upper Mississippi River Valley with 0.75" GOES-derived PWATs encroaching on locally western counties in southeast Minnesota and northeast Iowa early this morning.
The resultant 5-10 degree swing in temperatures brings near-normal daytime highs across the forecast area; in the 70s for most. Have continued previous mention of showers through the morning hours on the lobe of the increased moisture transport most evident in satellite imagery.
While higher precipitation chances remain along and west of the local forecast area through today due to contention between the forcing synoptic wave and the aforementioned high pressure (LREF confidence in 579dam heights at 500mb), a meager east shift in the pattern does graze limited precipitation chances along northwestern peripheral counties in southeast Minnesota overnight.
Expect quite a tight PoP & QPF boundary due to local synoptic confluence, with HREF and LREF members exhibiting low level dry air plumes entrained within the anticyclonic flow (southeast of the boundary). Therefore confidence in local impacts and precipitation remains low to moderate (20-40%) for much of the forecast area until Tuesday when the more moist airmass advects east (20-60% PoPs).
Warming Through The Week:
The warming trend continues through the week as anomalous mid level heights (90th percentile in SPC climatology) build through the Central Plains (LREF). Current forecast hour leaves much to be desired in the way of confidence for exact details as GFS/GEFS warm bias forecasts a high of 88F/85F at La Crosse, contending with a 68F/73F high in the ECMWF/EPS. Resultant NBM 25th to 75th percentile spread is 5 to 15 degrees this weekend, largest on Sunday.
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.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/... Issued at 1155 AM CDT Mon Sep 8 2025
CIGS: skc/sct conditions into tonight with an increase in a mid level VFR deck as an upper level shortwave trough approaches from the west. Once in the cigs should hold through Tue night into the early part of Wed.
WX/vsby: scattered to areas of -shra will accompany the shortwave but will have to battle drier sub cloud layer/sfc inversion over the local area initially. Higher rain threat moves in later Tue night, persisting into Wed. Most CAMS and other short term guidance suggest scattered coverage with QPF also on the lower end (< 1/4"). Thunder threat also low (
NWS ARX Office Area Forecast Discussion