502  
FXUS63 KARX 211720  
AFDARX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE LA CROSSE WI  
ISSUED BY NATIONAL WEATHER SERVICE DULUTH MN  
1220 PM CDT WED MAY 21 2025  
   
KEY MESSAGES  
 
- CLOUDY AND SHOWERY/DRIZZLY TODAY INTO THIS EVENING WITH MANY  
AREAS SEEING ANOTHER 0.25-0.40” BEFORE DRIER AIR MOVES IN FOR  
THURSDAY.  
 
- COOLER THAN NORMAL TEMPERATURES WILL CONTINUE THROUGH THE  
NEXT WEEK WITH 40S/50 TODAY AND THEN THE 60S FOR HIGH  
TEMPERATURES. DEPENDING ON CLOUD COVER, LIGHT WINDS COULD  
PROMOTE SOME FROST FRIDAY MORNING IN CENTRAL WISCONSIN.  
 
- THE HOLIDAY WEEKEND LOOKS MAINLY DRY WITH NORTHEAST IA AND  
SOUTHERN WI POSSIBLY SEEING SOME SHOWER CHANCES ON THE  
NORTHERN SIDE OF CENTRAL/SOUTHERN U.S WEATHER SYSTEMS.  
CONFIDENCE IS LEANING TOWARD A DRIER FORECAST, BUT SOME SMALL  
CHANCES ARE IN THE FORECAST FOR LIGHT RAIN SHOWERS FOR THAT  
AREA.  
 
 
   
DISCUSSION  
 
ISSUED AT 310 AM CDT WED MAY 21 2025  
 
MORE RAIN EXPECTED TODAY INTO TONIGHT, THEN SOME DRYING  
 
GOES WATER VAPOR IMAGERY AT 06Z SHOWS THE BROAD LARGE SCALE  
TROUGH OVER THE UPPER MISSISSIPPI RIVER VALLEY WITH NUMEROUS  
SHORTWAVE TROUGHS PINWHEELING AROUND THE LOW. A STRONG EASTWARD  
PUSH IS SEEN TO THE SOUTHERN SIDE OF THE TROUGH IN THE ZONAL JET  
FLOW ACROSS THE OHIO VALLEY. A SHARP SURFACE TROUGH IS LOCATED  
FROM ABERDEEN SD TO AROUND THE I-80 CORRIDOR OF ILLINOIS WITH  
THE LOCAL AREA UNDER CONTINUED EASTERLY FLOW. PRECIPITABLE WATER  
VALUES REGIONALLY ARE STILL AROUND AN INCH, WITH GRB AND MPX  
SHOWING ABUNDANT SATURATION THROUGH MUCH OF THE TROPOSPHERE.  
RADAR IS SHOWING ABUNDANT SHOWER ACTIVITY AND RAINFALL AMOUNTS  
OF UP TO 0.30” IN THE LAST FEW HOURS.  
 
EAST/SOUTHEASTERLY FLOW IN THE LOW-LEVELS IS CONTINUING A MOIST  
FLOW WITH TROUGHING OVERHEAD TODAY AND CYCLONIC FLOW, ALL  
PROMOTING SATURATION, CLOUDS, DRIZZLE AND SHOWERS UNTIL THIS AIR  
MASS CAN SHIFT OUT OF THE AREA. THAT AIR MASS CHANGE COMES  
LATER TONIGHT AND EARLY THURSDAY AS A WELL AGREED UPON LARGE  
SCALE TROUGH SHIFTS IN FROM THE HUDSON BAY REGION TO PROVIDE  
SOME DRYING AND AN AIR MASS CHANGE FROM THE NORTH/NORTHEAST,  
EJECTING THE TROUGH OVER THE AREA DOWNSTREAM INTO THE EASTERN  
U.S. SOME LINGERING TROUGHINESS AT THE SURFACE ACROSS THE  
FORECAST AREA AND THE INFLUENCE OF COOLER AIR ALOFT FROM THE  
LARGE SCALE TROUGH OVER EASTERN LAKE SUPERIOR COULD STILL SPAWN  
A FEW SHOWERS THURSDAY AFTERNOON WITH STRATOCUMULUS DEVELOPMENT  
ASSURED. SO MAYBE SOME PEAKS OF SUN IN THE MORNING, THEN  
CLOUDING UP.  
 
THE COOLER PATTERN CONTINUES, FROST IS POSSIBLE FRIDAY MORNING  
 
THE AREA REMAINS UNDER THE INFLUENCE OF NORTHWEST FLOW AND AT  
TIMES IS BRUSHED BY SHORTWAVES MOVING THROUGH THE GREAT LAKES.  
NORMAL HIGHS THIS TIME OF YEAR ARE NOW IN AT LEAST THE UPPER 60S  
INTO THE 70S, BUT THE FORECAST CONTINUES TO SHOW TEMPERATURES  
WILL BE BELOW THAT BY 6-10 DEGREES INTO NEXT WEEK. WITH WEAK  
HIGH PRESSURE BUILDING IN AT THE SURFACE FOR FRIDAY, DEPENDING  
ON THE EXTENT OF CLOUD COVER, SOME FROST COULD BE OBSERVED IN  
CENTRAL WI IN THE MORNING. THE LATEST NBM WOULD PUT A 20-30%  
CHANCE THERE FOR 35F OR LESS. HOWEVER, THE PROBABILITIES ARE  
LIKELY HIGHER WITH THE WARM BIAS SHOWN BY ALL THE MODELS ON  
THESE RADIATIVE NIGHTS IN THE SAND COUNTRY / BOGS OF CENTRAL WI.  
WILL HAVE TO SEE THE CLOUD EXTENT DETAILS AS WE APPROACH FRIDAY  
MORNING FOR THE FROST POTENTIAL. AFTER THAT, TEMPERATURES  
SHOULD MODERATE SLIGHTLY TO AVOID FROST/FREEZE BUT NORTHERLY  
FLOW PERSISTS AT THE LOW-LEVELS.  
 
HOLIDAY WEEKEND FORECAST  
 
BY SATURDAY NIGHT AND SUNDAY, TROUGHING MOVING INTO THE  
CENTRAL/SOUTHERN PLAINS WILL BATTLE THE GREAT LAKES RIDGING AND  
DRIER EASTERLY FLOW, TRYING TO PUSH MOISTURE AND PRECIPITATION  
CHANCES IN ACROSS AREAS SOUTH AND WEST OF LA CROSSE. IT REMAINS  
TO BE SEEN IF THE ACTIVITY ACROSS THE CENTRAL/SOUTHERN PLAINS  
CAN OVERCOME THE DRY AIR IN PLACE FOR SHOWERS THIS FAR NORTH.  
THE LATEST 20.12Z GRAND ENSEMBLE AVAILABLE SUGGESTS THIS  
PROBABILITY IS LOW WITH THE GEFS SOLUTIONS PROVIDING A MORE  
AGGRESSIVE FORECAST FOR RAIN. SOME LOW CHANCES FOR RAIN ARE OUT  
THERE FOR THE WEEKEND FORECAST, BUT THOSE MAY BE REMOVED IN  
FUTURE FORECASTS BASED ON TRENDS ON THE NORTHERN EXTENT OF THE  
SYSTEMS MOVING THROUGH TO THE SOUTH. ON MONDAY, YET ANOTHER  
SHORTWAVE TROUGH INFLUENCES THE AREA FROM THE NORTHWEST AND HAS  
MODERATE CONFIDENCE AND AGREEMENT IN THE MODELS FOR SOME SHOWER  
CHANCES.  
 
 
   
AVIATION /18Z TAFS THROUGH 18Z THURSDAY/  
 
ISSUED AT 1220 PM CDT WED MAY 21 2025  
 
IFR TO MVFR CONDITIONS WILL CONTINUE FOR THE TAF SITES INTO  
TONIGHT AS A TROUGH LINGERS ACROSS THE AREA. NUMEROUS SHOWERS  
WILL BE SEEN INTO THIS EVENING. WHILE DRIER AIR WILL MOVING INTO  
THE REGION OVERNIGHT, LOW LEVEL MOISTURE WILL LIKELY REMAINED  
TRAPPED UNDERNEATH A NOCTURNAL INVERSION. THIS INVERSION SHOULD  
BREAK AROUND 22.14Z. THERE WILL BE LIKELY BE A BRIEF PERIOD OF  
SCATTERED LOW CLOUDS AND THEN AS DIURNAL HEATING OCCURS 900-800  
MB LAPSE RATES WILL STEEPEN AND A BROKEN TO OVERCAST 3-5K DECK  
OF CLOUDS WILL QUICKLY DEVELOP. WINDS WILL BE NORTH AROUND 10  
KNOTS THROUGH THIS EVENING AND THEN BECOME NORTHWEST AND  
INCREASE TO 10 TO 15 KNOTS ON THURSDAY MORNING.  
 
 
   
ARX WATCHES/WARNINGS/ADVISORIES  
 
WI...NONE.  
MN...NONE.  
IA...NONE.  
 
 
 
 
 
DISCUSSION...BAUMGARDT  
AVIATION...BOYNE/WOLFE  
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