376  
FXUS63 KARX 201759  
AFDARX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE LA CROSSE WI  
1259 PM CDT FRI JUL 20 2018  
   
SHORT TERM
 
(TODAY AND TONIGHT)  
ISSUED AT 316 AM CDT FRI JUL 20 2018  
 
MAIN FORECAST CONCERNS ARE ON SCATTERED SHOWERS AND THUNDERSTORMS  
TODAY.  
 
LOW PRESSURE WILL TRACK INTO SOUTHEAST WISCONSIN BY THIS  
AFTERNOON WITH SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS  
EXPECTED ACROSS THE AREA TODAY. INSTABILITY IS LIMITED OVER THE  
REGION WITH MUCAPE VALUES OF ONLY 200 TO PERHAPS 300 J/KG. SHEAR  
IS ALSO VERY WEAK OVER THE AREA THANKS TO THE LOW BEING OVERHEAD  
WITH 0-6 KM BULK SHEAR VALUES OF 20 KTS OR LESS. THE MAIN THREAT  
FROM ANY THUNDERSTORM TODAY WILL BE LIGHTNING. WILL HAVE TO KEEP A  
CLOSE EYE ON ANY SURFACE BOUNDARIES WITH THE OUTSIDE CHANCE OF A  
COLD AIR FUNNEL. CURRENTLY NOT SEEING A FAVORABLE BOUNDARY AT THIS  
TIME IN THE FORECAST MODEL OUTPUT. RAINFALL AMOUNTS ACROSS THE  
REGION TODAY WILL RANGE FROM AROUND 1/10 INCH OVER PORTIONS OF  
NORTHEAST IOWA AND SOUTHEAST MINNESOTA TO AROUND 1/2 INCH OVER  
CENTRAL WISCONSIN. SHOWERS AND THUNDERSTORMS GRADUALLY TAPER OFF  
THEN THIS EVENING INTO THE OVERNIGHT WITH ANY LINGERING ACTIVITY  
CONFINED TO WESTERN AND CENTRAL WISCONSIN AFTER MIDNIGHT.  
   
LONG TERM
 
(SATURDAY THROUGH THURSDAY)  
ISSUED AT 316 AM CDT FRI JUL 20 2018  
 
THE LOW THEN SLOWLY MEANDERS SOUTHEAST OVER SOUTHERN LAKE MICHIGAN  
INTO NORTHERN INDIANA ON SATURDAY WITH CHANCES FOR SHOWERS AND  
PERHAPS AN ISOLATED THUNDERSTORM PERSISTING FOR AREAS ALONG AND EAST  
OF THE MISSISSIPPI RIVER. THE LOW THEN FINALLY PUSHES SOUTHEAST  
OF THE REGION INTO THE OHIO RIVER VALLEY SATURDAY NIGHT INTO  
SUNDAY. A TRAILING TROUGH THEN SWINGS IN FROM THE NORTHEAST ON  
SUNDAY WHICH COULD GENERATE A FEW SHOWERS AND STORMS OVER WESTERN  
AND CENTRAL WISCONSIN. HOWEVER, CONFIDENCE IS LOW ON THIS  
HAPPENING SO HAVE KEPT THE FORECAST DRY FOR SUNDAY BUT WILL HAVE  
TO KEEP A CLOSE EYE ON THIS POTENTIAL. WEAK HIGH PRESSURE SETTLES  
IN FOR SUNDAY NIGHT WITH DRY WEATHER EXPECTED. LOW PRESSURE IS  
EXPECTED TO MEANDER INTO NORTHERN MANITOBA MONDAY AFTERNOON INTO  
TUESDAY DRAGGING A VERY WEAK COLD FRONT INTO THE REGION. THIS  
FRONT MAY GENERATE A FEW SHOWERS OR STORMS, MAINLY DURING THE  
AFTERNOON HOURS. ANOTHER FRONT THEN LOOKS TO MAKE ITS WAY THROUGH  
THE AREA ON WEDNESDAY POSSIBLY GENERATING SCATTERED SHOWERS AND  
STORMS ACROSS THE AREA ONCE AGAIN. UPPER TROUGH SETS UP ACROSS THE  
UPPER MISSISSIPPI RIVER VALLEY FOR THE LAST HALF OF THE WEEK WITH  
TEMPERATURES REMAINING SLIGHTLY BELOW NORMAL.  
 

 
   
AVIATION
 
(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)  
ISSUED AT 1238 PM CDT FRI JUL 20 2018  
 
LOW PRESSURE CONTINUES TO MOVE SOUTHEASTWARD ACROSS MINNESOTA AND  
INTO SOUTHWESTERN WISCONSIN TODAY. THIS WILL BRING VCSH TO KRST  
AND KLSE THROUGH 00 UTC ON SATURDAY. THE BETTER CHANCE OF -SHRA  
ARE AT KLSE WHERE MVFR VISIBILITIES ARE POSSIBLE IN HEAVIER  
SHOWERS. CEILINGS ARE FORECAST TO SLOWLY IMPROVE INTO THIS EVENING  
BEFORE DROPPING AGAIN TO MVFR TO IFR AFTER 06 UTC. GUSTY  
NORTHWEST WINDS WILL DIMINISH BY 23 UTC.  
 

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

 
 

 
 
SHORT TERM...WETENKAMP  
LONG TERM...WETENKAMP  
AVIATION...COUSINS  
 
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