FXUS63 KARX 190308

AFDARX



Area Forecast Discussion

National Weather Service La Crosse WI

1008 PM CDT Wed Mar 18 2026



.KEY MESSAGES...



- Warmer, more moist airmass raises nightly fog concerns for

  much of the area through late week. 



- Confidence (60%) in anomalous warmth initially reaches the 

  forecast area Friday, increasing (70%) for Saturday.  



- Moderate confidence (50-70%) for light precipitation Saturday

  night through Sunday. Low confidence in exact location or 

  potential for higher amounts (0.1"+). 



&&



.DISCUSSION...

Issued at 957 PM CDT Wed Mar 18 2026



Warming Into Early Weekend, Potential Nightly Fog:



Outside of nightly fog, a relatively quiet period of sensible 

weather is expected after ongoing mixed precipitation potential

in central Wisconsin exits east of the local forecast area 

tonight. Main forecast detail will be advection of anomalously 

warm temperatures into the early weekend and subsequent 

potential preciptiation.



The two main phenomena that will have the largest impact on 

sensible weather locally will be the dense, climatologically 

thick snowpack observed and exact location of a relatively 

diffuse baroclinic boundary strewn northwest to southeast west 

of the Upper Mississippi River Valley tonight, flirting 

east/west over the forecast area as meager waves meander along 

it into this weekend. A farther northeast advection of the warm,

moist airmass will increase nightly fog potential and degree of

hottest temperatures into Saturday. 



Confidence In Warmest Temperatures:



While our on doorstep for Thursday, NBM (18.19Z) probabilities for 

the 60 degree isotherm greatly increase (25-75%) initially Friday 

along our western peripheral counties and into southwest Wisconsin. 

Further warming into the weekend ushers in similar probabilities for 

the 70 degree isotherm locally. Although, high Interquartile Spread 

(25th-75th percentile) of 10-15 degrees over southeast Minnesota on 

Friday spreads across the forecast area on Saturday. Again,  amount 

of melting and resultant albedo will be crucial, ultimate factor to 

monitor Thursday and Friday as the baroclinic boundary attempts to 

advect northeast through the forecast area with passing waves. 



Low Confidence In Late Weekend Precipitation:



The synoptic pattern breaks through the end of the weekend, ushering 

in more normal daytime highs in the 40s to 50s through Sunday and 

low confidence in widespread precipitation potential with the 

passing cold frontal boundary Saturday night through Sunday. As potential

cyclogenesis passes near the forecast area, confidence in precipitation

potential (50-70%) agrees between long term global ensembles 

whilst disagreeing within respective ensemble runs. The GEFS 

(18.18Z) increased probabilities for 0.01" of QPF in 24 hours 

compared to previous run (18.12Z), 50-70% along and east of the 

Mississippi River, while the most recent EPS (18.18Z) decreased 

to similar probabilities in most recent run. Interensemble 

confidence for higher amounts (0.1"/24hr) increases northeast 

of the forecast area, lowest (<15%) in most recent EPS (18.18Z).



&&



.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...

Issued at 636 PM CDT Wed Mar 18 2026



A mix of light rain and freezing rain will impact locally

northern smaller airports in central Wisconsin (KMDZ) tonight.

Increasing low level moisture over snow covered, cold ground

will cause widespread FG elsewhere, including both TAF sites

(KLSE & KRST). Therefore, have included 1/4SM mention overnight

at 19.00Z issuance. Difficulty discerning duration of largest

impacts through Thursday and have included lingering lifting

through the late morning but will require further adjustment in

coming 19.06Z TAF issuance.



&&



.ARX WATCHES/WARNINGS/ADVISORIES...

WI...None.

MN...None.

IA...None.



&&$$



DISCUSSION...JAR

AVIATION...JAR