207  
FXUS63 KARX 071942  
AFDARX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE LA CROSSE WI  
242 PM CDT SUN AUG 7 2022  
   
DISCUSSION
 
(THIS EVENING THROUGH SUNDAY)  
ISSUED AT 242 PM CDT SUN AUG 7 2022  
 
KEY MESSAGES:  
 
- POTENTIAL FOR FLASH FLOODING/HEAVY RAIN AGAIN TONIGHT  
 
TONIGHT INTO MONDAY...FLASH FLOODING/HEAVY RAIN POTENTIAL  
 
THE POTENTIAL EXISTS FOR ANOTHER ROUND OF HEAVY RAIN THAT COULD  
LEAD TO SOME FLASH FLOODING. HOWEVER, THE SIGNALS ARE NOT QUITE AS  
CLEAR AS SATURDAY, WHICH CASTS SOME DOUBT ON HOW THINGS WILL  
EVOLVE. THE SYNOPTIC SURFACE FRONT IS STRETCHED OUT FROM SOUTHEAST  
NEBRASKA INTO EAST-CENTRAL WISCONSIN AND MAY BECOME A FOCUS FOR  
ADDITIONAL DEVELOPMENT OF STORMS/HEAVY RAIN THIS EVENING. THE RAP  
STARTS TO INCREASE THE LOW LEVEL MOISTURE TRANSPORT AGAIN THIS  
EVENING AHEAD OF A RATHER STRONG SHORT WAVE TROUGH. THIS MOISTURE  
TRANSPORT LOOKS TO INITIALLY BE FOCUSED INTO THE FRONT WITH A  
CORRESPONDING DEVELOPMENT OF AN EAST/WEST LINE OF STORMS FROM  
NORTHEAST IOWA INTO SOUTHWEST WISCONSIN, WHICH IS ROUGHLY WHERE  
THE 925 MB BAROCLINIC ZONE LOOKS TO RESIDE. THE ATMOSPHERE IN THIS  
REGION IS RIPE FOR HEAVY RAIN PRODUCTION WITH WARM CLOUD DEPTHS  
IN THE 4 TO 4.5 KM RANGE AND PRECIPITABLE WATER AMOUNTS  
APPROACHING 2.5 INCHES.  
 
THE CONCERN THEN BECOMES WHETHER THESE FEATURES WILL REMAIN  
SOMEWHAT STATIONARY OR IF THEY WILL GET LIFTED NORTH THROUGH THE  
NIGHT IN RESPONSE TO THE LARGE SCALE FORCING FROM THE SHORT WAVE  
TROUGH. THIS FORCING IS PRETTY STRONG WITH EXCELLENT PV ADVECTION  
IN THE 500-300 MB LAYER EXPECTED ON THE POLEWARD SIDE OF THE  
POSITIVE TILTED SHORT WAVE TROUGH. THIS PV ADVECTION LOOKS TO  
TRACK ACROSS NORTHERN MINNESOTA AND FAR NORTHERN WISCONSIN BUT  
THERE ALSO LOOKS TO BE SOME JET DYNAMICS THAT COME INTO PLAY. THE  
RIGHT ENTRANCE OF THE 300 MB JET LOOKS TO BE IN PLACE AHEAD OF THE  
SHORT WAVE TROUGH ITSELF AND SHOULD BRING IT LIFT OVER THE  
NORTHERN PARTS OF THE AREA. THIS SYNOPTIC FORCING IS EXPECTED TO  
CAUSE A WEAK AREA OF SURFACE LOW PRESSURE TO FORM OVER FAR EAST-  
CENTRAL MINNESOTA AND THEN TRACK INTO NORTHWEST WISCONSIN. AS THE  
SHORT WAVE TROUGH AND SURFACE LOW MOVE EAST/NORTHEAST IT IS ALSO  
EXPECTED TO GIVE THE LOW LEVEL FORCING A PUSH TO THE EAST. AND  
THEN THERE IS THE QUESTION OF WHETHER THE LOW LEVEL JET/MOISTURE  
TRANSPORT WILL REMAIN FOCUSED TO THE SOUTH OR GET PULLED FARTHER  
NORTH AS THE RAP IS SUGGESTING THE SYNOPTIC FRONT GETS PULLED  
NORTH WITH THE SURFACE LOW. BUT AT THE SAME TIME, THERE IS STILL A  
SIGNAL OF THE 925 MB FRONT REMAINING OVER NORTHEAST IOWA AND  
SOUTHWEST WISCONSIN THROUGH THE EVENING THAT COULD KEEP THE LOW  
LEVEL FORCING ANCHORED FARTHER SOUTH. AFTER MIDNIGHT, IT LOOKS  
LIKE THE MOVEMENT OF THE SHORT WAVE TROUGH/SURFACE LOW WILL BE  
ENOUGH TO START PUSHING EVERYTHING TO THE EAST AND OUT OF THE AREA  
BY SUNRISE. EVEN IF THE LOW LEVEL FORCING REMAINS TO THE SOUTH,  
THERE SHOULD STILL BE ENOUGH FORCING FROM THE SHORT WAVE TROUGH  
FOR A ROUND OF CONVECTION TO MOVE ACROSS MOST OF THE AREA.  
 
LOOKING AT THE 07.12Z HREF, THE GENERAL QPF AMOUNTS DO NOT LOOK  
TO BE AS HIGH AS ON PREVIOUS RUNS BUT STILL A SIGNAL FOR SOME  
HEAVY RAIN PRODUCTION. THE 24 HOUR LPMM SHOWS TWO DISTINCT  
POTENTIAL AXISES FOR HEAVY RAIN. ONE ON THE LOW LEVEL JET THIS  
EVENING ACROSS NORTHEAST IOWA INTO SOUTHWEST WISCONSIN WHERE  
AMOUNTS ARE GENERALLY IN THE 1 TO 3 INCH RANGE. A GOOD SIGNAL IN  
THIS AREA FOR RATES TO BE AN INCH PER HOUR WITH JUST A SMALL  
SIGNAL (20 OR LESS) FOR 2 INCH PER HOUR RATES. THE AREA OF CONCERN  
IS IN RESPONSE TO THE SYNOPTIC FORCING ACROSS PARTS OF SOUTHEAST  
MINNESOTA INTO WESTERN WISCONSIN WHERE AGAIN THE LPMM SHOWS 1 TO 3  
INCH AMOUNTS POSSIBLE. IN A WORST CASE SCENARIO, THE MAX QPF FROM  
THE HREF SHOWS THE POTENTIAL FOR AMOUNTS TO EXCEED 3 INCHES THIS  
EVENING ACROSS THE SOUTH AND ALSO FARTHER TO THE NORTH THROUGH THE  
ENTIRE NIGHT. FORTUNATELY, THIS LOOKS TO BE NORTH OF WHERE THE  
HEAVIEST RAINS FELL SATURDAY NIGHT, BUT WITH MOST AREAS RECEIVING  
RAINS, THE STORAGE CAPACITY OF THE GROUND HAS BEEN REDUCED. AS A  
RESULT, MORE RUNOFF COULD BE GENERATED OVERNIGHT THAT MAY LEAD TO  
HIGHER POTENTIAL FOR FLOODING TO OCCUR AND NOT PLANNING TO MAKE  
ANY CHANGES TO THE CURRENT FLASH FLOOD WATCH.  
 

 
   
AVIATION
 
(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)  
ISSUED AT 112 PM CDT SUN AUG 7 2022  
 
THUNDERSTORM CHANCES RETURN TO THE AREA THIS EVENING. MVFR  
CONDITIONS WILL PERSIST, WITH REDUCTIONS IN VISIBILITY POSSIBLE  
DURING PERIODS OF HEAVY RAIN AND FOG. CEILINGS WILL CONTINUE TO  
LOWER INTO IFR THROUGH THE NIGHT, AND WILL START TO RAISE BACK TO  
MVFR/VFR BY TOMORROW EARLY AFTERNOON. WINDS WILL BE LIGHT AND  
VARIABLE AS A SURFACE LOW MOVES THROUGH THE AREA, EVENTUALLY  
INCREASING OUT OF THE NORTHWEST AS THE LOW MOVES OUT.  
 

 
   
HYDROLOGY
 
 
ISSUED AT 242 PM CDT SUN AUG 7 2022  
 
EVEN WITH THE RAINS LAST NIGHT, THERE HAS BEEN A VERY MUTED  
RESPONSE ON THE RIVERS SHOWING THE STORAGE CAPACITY OF THE GROUND  
WAS VERY HIGH. WITH MORE RAIN EXPECTED AGAIN OVERNIGHT, THE LATEST  
RIVER FORECASTS DO SHOW SOME ADDITIONAL RISES OCCURRING, BUT SO  
FAR, THESE RISES ARE EXPECTED TO BE BELOW FLOOD STAGE AT ALL  
FORECAST POINTS. THIS COULD CHANGE THOUGH IF THE RAINS TONIGHT  
WOULD SET UP OVER NORTHEAST IOWA WHERE BOTH THE CEDAR AND TURKEY  
RIVER BASINS COULD BE IMPACTED.  
 

 
   
ARX WATCHES/WARNINGS/ADVISORIES
 
 
WI...FLOOD WATCH THROUGH MONDAY MORNING FOR WIZ032>034-041>044-  
053>055-061.  
 
MN...FLOOD WATCH THROUGH MONDAY MORNING FOR MNZ079-086>088-094>096.  
 
IA...FLOOD WATCH THROUGH MONDAY MORNING FOR IAZ008>011-018-019-029-  
030.  
 

 
 

 
 
DISCUSSION...04  
AVIATION...EMS  
HYDROLOGY...04  
 
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