134 FXUS63 KARX 151058 AFDARXArea Forecast Discussion National Weather Service La Crosse WI 558 AM CDT Wed Oct 15 2025
.KEY MESSAGES...
- Precipitation chances linger across southwestern half of the local forecast area through today.
- High precipitation chances overnight into Thursday morning and Friday morning through Saturday morning.
- Warmer than normal temperatures Thursday and Friday with daytime highs in the 70s for some.
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.DISCUSSION... Issued at 329 AM CDT Wed Oct 15 2025
Lingering Rainfall Chances Today:
A pool of anomalous (SPC climatology) moisture is situated over the forecast area, from maximum percentile PWATs (DVN 15.00Z) RAOB) bifurcating the southern half of the forecast area to 90th percentile (GRB/MPX 15.00Z RAOBs) to the north. Expect this boundary to linger through much of today due to flattening of the upper level ridge periphery evident on GOES upper level water vapor imagery loops, signifying weakening of meridional moisture transport. An axis of dilatation situated between high pressure centers north and south of the forecast area will perpetuate precipitation chances where this increased moisture lies across the southwestern half of the forecast area from southeast Minnesota through northeast Iowa into far southwest Wisconsin. Therefore, have increased PoPs through tonight in collaboration with neighboring offices. While moisture remains anomalous, a lack of strong forcing limits overall rainfall amounts near 0.5" (HREF) with higher amounts near 1"+ possible in spots where heavier rainfall rates temporarily occur according to HREF LPMM and ensemble maximum.
Precipitation Chances Thursday
An upper level low lifting north over the Sierra Nevadas on early morning GOES water vapor imagery will reinvigorate meridional moisture transport later today, eventually forming a strong Midwest Atmospheric River of 850-1000 kg m-1 s-1 integrated vapor transport overnight through Thursday. Current trajectory places the anomalous moisture (3+ standardized model climate anomalies in NAEFS/ENS) between the Missouri and Mississippi River valleys, advecting as far north as central Ontario (Moosoonee, ON RAOB per SPC climatology) in LREF PWAT probabilities this weekend. LREF confidence limits highest impacts well to the west of the forecast area into the northern Plains with location of initial cyclogenesis resulting in ECMWF extreme forecast QPF indices of 0.92 with a shift of tails of 2 from North Dakota into Montana on Friday. Local precipitation chances, will lift northeast overnight through Thursday providing another 0.5" through Thursday primarily along western half of the forecast area, tied to the tightening surface pressure gradient, accompanying forcing from resultant low level jet, and stronger low level isentropic upglide. Higher amounts near 1"+ will be possible where scattered, heavier rainfall rates repeat.
Precipitation Chances Friday & Saturday:
As the moist air exits northeast, a short reprieve in higher precipitation chances is expected overnight Thursday into Friday morning. Extent and duration of any drying remains unclear as LREF members suggest cyclogenesis along lingering baroclinic boundary although overall forcing remains questionable. Subsequent upper level northwest flow (LREF) zonally advects the upper level trough axis and accompanying surface front across the Upper Midwest Friday through Saturday. Current confidence in local impacts remains limited to heavy rain as SBCAPE/MUCAPE values remain 150 to 300 J/kg (LREF). LREF confidence near 50% for a widespread 0.25" to 0.5".
Warm
Eastern extent of main plume of excited return flow will determine magnitude of anomalous temperatures Thursday with current LREF/HREF/NBM confidence for the 90th percentile 70 degree isotherm grazing our southwestern peripheral counties in northeast Iowa and southeast Minnesota. More widespread probabilities for the 70 degree isotherm for Friday as frontal boundary advects east across the Upper Mississippi River Valley. Maximum temperature records at La Crosse (84) and Rochester (85) do not appear in jeopardy.
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.AVIATION /12Z TAFS THROUGH 12Z THURSDAY/... Issued at 554 AM CDT Wed Oct 15 2025
Widespread flight rule restrictions are ongoing and expected to continue over the next 24 hours. Many locations as of issuance time are experiencing IFR/LIFR conditions due to light rain and stratus. As rain probability tapers off this morning, expect this to improve slightly through the day to mainly MVFR/IFR conditions by around mid- afternoon. An additional round of rain may occur after 06z but refrained from using PROB30 groups to cover with this issuance since this falls outside the critical TAF period.
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.ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None.
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DISCUSSION...JAR AVIATION...Ferguson
NWS ARX Office Area Forecast Discussion