712  
FXUS63 KARX 071140  
AFDARX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE LA CROSSE WI  
640 AM CDT THU JUL 7 2022  
   
DISCUSSION
 
(TODAY THROUGH WEDNESDAY)  
ISSUED AT 245 AM CDT THU JUL 7 2022  
 
KEY MESSAGES:  
 
- ISOLATED TO SCATTERED SHOWER/T-STORM CHANCES TODAY/TONIGHT  
 
- RAIN CHANCES EXITING FRIDAY AFTERNOON THROUGH SATURDAY BUT RETURN  
SUNDAY AFTERNOON THROUGH MONDAY  
 
- SEASONABLE TEMPERATURES CONTINUE INTO NEXT WEEK  
 
WATER VAPOR SATELLITE IMAGERY, LIGHTNING, AND 500MB HEIGHTS SHOW A  
TROUGH APPROACHING THE PACIFIC NORTHWEST WITH A RIDGE OVER THE  
ROCKIES EXTENDING TOWARD THE SOUTHERN PLAINS AND GULF STATES.  
NORTHWEST FLOW ALOFT WAS OVER THE LOCAL AREA INTO THE GREAT LAKES  
AND NEW ENGLAND STATES. SEVERAL AREAS OF CONVECTION WERE OCCURRING  
EARLY THIS MORNING WITH ORGANIZED CLUSTERS OVER EASTERN COLORADO,  
OVER THE NEB/KS STATE LINES INTO NORTHERN MISSOURI NEAR THE SURFACE  
FRONT AND ALSO ACROSS MONTANA. THE MPX 00Z SOUNDING HAD A 1.18"  
PRECIPITABLE WATER VALUE (PWAT) WITH A WEAK CAP IN PLACE TO 666MB.  
PWATS ALONG THE FRONT ACROSS NORTHERN MISSOURI WERE IN THE 2" TO  
2.25". THE FRONT ACROSS NORTHERN MONTANA HAD PWATS OF 1.4 INCHES.  
 
TODAY THROUGH FRIDAY, WE'LL BE MONITORING THE PROGRESS OF THE  
SHORTWAVE TROUGHS MOVING EAST FROM MONTANA AND FROM COLORADO ACROSS  
THE PLAINS TODAY AND INTO IOWA/MINNESOTA. POCKETS OF UPPER LEVEL  
JET SUPPORT ARE ASSOCIATED WITH THESE FEATURES, MID LEVEL  
FRONTOGENESIS, AND VORTICITY ADVECTION WITH THE SHORTWAVES. AS IS  
TYPICAL, THE HI RESOLUTION MODELS HAVE A VARIETY OF SOLUTIONS WITH  
THE HIGHER CONFIDENCE CLOSER TO THE SURFACE FRONTS AS THESE  
SHORTWAVE TROUGHS PUSH INTO THE AREA. THE NAM APPEARS TO SUFFER  
FROM CONVECTIVE FEEDBACK WITH A MUCH STRONGER SOLUTION/STRONGER  
MOISTURE TRANSPORT FARTHER NORTH ACROSS EASTERN IOWA INTO NORTHERN  
ILLINOIS COMPARED TO THE OTHER DETERMINISTIC MODELS FOR TONIGHT AND  
FRIDAY. WHILE THE GFS HAS A MORE MUTED SIGNAL AND THE EC HEAVY RAIN  
APPROACHING THE SOUTHERN PART OF THE FORECAST AREA. SPC  
MESOANALYSIS GRAPHICS AND 850MB ANALYSIS DATA SHOW A VERY MOIST  
ATMOSPHERE IS IN PLACE OVER THE LOCAL AREA WITH 1.6 INCHES OF  
PRECIPITABLE WATER. FORECAST SOUNDINGS FROM THE RAP SHOW LOW  
LEVEL INSTABILITY IN PLACE THIS MORNING WITH A WEAK CAP AND  
INSTABILITY ABOVE THE CAP...THEN THE CAP ERODING THIS AFTERNOON  
WITH SBCAPE INCREASING TO AROUND 1200 J/KG AT KRST WITH THE CAP  
WEAKENING A LITTLER EARLIER...AFTER 10AM. THE RAP/HRRR FORECAST  
SOUNDINGS WERE ON THE WEAKER SIDE WITH 20KTS OF DEEP LAYER SHEAR.  
CLOUD LAYER WINDS ARE 5 TO 15KTS, THUS SLOW MOVING. WITH THE  
SHORTWAVE TROUGH TODAY THROUGH FRIDAY, THE AIRMASS SUPPORTS  
ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS. THE HRRR SEEMS TO  
HANDLE THE CURRENT CONVECTION WELL WITH NOT MUCH LOCALLY THROUGH  
THE DAY WITH A BAND OF SHOWERS/STORMS INCREASING AFTER 23Z NEAR  
I90 AND PUSHING SOUTH AND ANOTHER BAND AROUND 10Z INTO EARLY  
FRIDAY MORNING. THE 07.00Z HREF ALSO SUPPORTS SOME ISO/SCT  
CONVECTION, BUT TOUGH TO CALL WHO WILL GET WET DUE TO THE HIT AND  
MISS COVERAGE. ORGANIZED SEVERE WEATHER APPEARS LOW DUE TO THE LOW  
SHEAR AND LOWER INSTABILITY, HOWEVER THE MOIST AIRMASS AND SLOW  
STORM MOVEMENT SUPPORT HEAVY DOWNPOURS WHERE STORMS DO  
FORM...INCREASING WITH HEATING TODAY AND THE HIGHER PROXIMITY TO  
THE SHORTWAVE TONIGHT INTO EARLY FRIDAY. THE GEFS PLUMES HAVE  
AROUND A QUARTER TO A THIRD OF AN INCH OF RAIN AT KLSE/KRST. THE  
EC EPS IS SIMILAR WITH .2 OR .3" AT KLSE/KRST. OVER HALF THE  
MEMBERS DO NOT HAVE 0.1" AND A COUPLE MEMBER HAVE 1 TO 2 INCHES.  
THE CURRENT EXCESSIVE RAINFALL OUTLOOKS IN THE SLIGHT OR MODERATE  
CATEGORY REMAIN TO THE SOUTH OF THE FORECAST AREA...SOUTH OF  
WATERLOO AND DUBUQUE. THE FLOOD WATCHES REMAIN SOUTH OF OUR  
FORECAST AREA CLOSER TO THE SURFACE FRONT.  
 
CLOUD COVERAGE REMAINS ON THE HIGHER SIDE TODAY THROUGH FRIDAY  
MORNING AND THIS SHOULD HELP KEEP TEMPERATURES IN THE 76 TO 85  
DEGREE RANGE. IT WILL REMAIN MUGGY TODAY, BUT NOT QUITE AS MUGGY  
LATER FRIDAY. STILL SEASONABLE FOR SATURDAY AS SURFACE HIGH  
PRESSURE BUILDS INTO THE AREA, BUT NOT AS HUMID WITH DEWPOINTS IN  
THE 50S.  
 
A SHOWER OR STORM MAY MAKE IT INTO THE FORECAST AREA SUNDAY NORTH OF  
I90, BUT A BETTER CHANCE WILL BE WITH THE LOWERING HEIGHTS AS A  
SHORTWAVE TROUGH BREAKS DOWN THE RIDGE WITH A COLD FRONT MOVING INTO  
THE REGION SUNDAY NIGHT AND MONDAY. WARMER HIGHS IN THE 80S AND A  
RETURN TO 60S DEWPOINTS FOR SUNDAY AND MONDAY. RAIN CHANCES LOOK  
SPOTTY TUESDAY AND WEDNESDAY WITH SEASONABLE HIGHS FROM THE MID 70S  
TO MID 80S.  
 

 
   
AVIATION
 
(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)  
ISSUED AT 638 AM CDT THU JUL 7 2022  
 
FOG IMPACTING RST THIS MORNING WILL DISSIPATE IN THE NEXT HOUR OR  
TWO. EXPECT MVFR VISIBILITIES AND IFR/LIFR CEILINGS UNTIL THEN. VFR  
CONDITIONS ARE FORECAST FOR MOST OF TODAY WITH SHOWER AND STORM  
CHANCES INCREASING THIS EVENING. STILL PLENTY OF UNCERTAINTY WITH  
THIS SYSTEM, SO PRECIP TIMING AND THUNDER CHANCES MAY NEED TO BE  
ADJUSTED IN FUTURE FORECASTS. LIGHT WINDS THROUGH THE TAF PERIOD  
STARTING OUT SOUTHEASTERLY BEFORE SHIFTING TO EAST/NORTHEASTERLY  
OVERNIGHT.  
 

 
   
ARX WATCHES/WARNINGS/ADVISORIES
 
 
WI...NONE.  
MN...NONE.  
IA...NONE.  

 
 

 
 
DISCUSSION...ZAPOTOCNY  
AVIATION...KAA  
 
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