957  
FXUS63 KARX 260825  
AFDARX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE LA CROSSE WI  
325 AM CDT WED APR 26 2017  
   
SHORT TERM
 
(TODAY THROUGH THURSDAY)  
ISSUED AT 325 AM CDT WED APR 26 2017  
 
THE FRONTAL BOUNDARY EARLY THIS MORNING EXTENDS FROM NORTHERN  
WISCONSIN BACK INTO EASTERN IOWA. BROAD LOW/MID LEVEL WARM  
ADVECTION AND MID-LEVEL FRONTAL FORCING HAS LED TO AREAS OF  
SHOWERS EARLY THIS MORNING. EXPECT SOME SHOWERS TO CONTINUE TO  
LIFT NORTHWARD DURING THE DAYTIME MORNING HOURS WITH THE LOWER TO  
MID LEVEL FRONTAL ZONE NEARBY. THE GFS/ECMWF CONTINUE TO REMAIN  
IN GOOD AGREEMENT WITH A RELATIVELY PROGRESSIVE SOLUTION, LIKELY  
PUTTING AN END TO THE BULK OF THE PRECIP OVER MUCH OF THE AREA BY  
LATER MORNING/EARLY AFTERNOON. THE EXCEPTION MAY BE AREAS MAINLY  
EAST OF THE MISSISSIPPI RIVER, ESPECIALLY FAR SOUTHWEST INTO  
CENTRAL WISCONSIN, IN CLOSER PROXIMITY TO THE UPPER WAVE AND  
STRONGER MID/UPPER FORCING LIFTING NORTHEASTWARD WHERE SHOWER  
CHANCES WILL CONTINUE INTO THURSDAY. A BIT OF WINTRY MIX/DRIZZLE  
IS NOT OUT OF THE QUESTION TONIGHT, ESPECIALLY NORTH OF I-90,  
DEPENDENT ON SURFACE TEMPS, BUT WITH LITTLE IMPACT EXPECTED. TEMPS  
WILL BE STEADY OR FALLING AS THE COLD FRONT SLIDES THROUGH ALONG  
AND WEST OF THE MISSISSIPPI RIVER TODAY, WHILE FARTHER EAST TEMPS  
MAY HAVE SOME TIME TO RECOVER BEFORE THE FRONT SLIDES THROUGH.  
 
BEHIND THE FRONT TOMORROW WILL BE A STARK CHANGE FROM TODAY WITH  
HIGHS REACHING NO HIGHER THAN THE 40S AND LOW STRATUS HANGING  
AROUND UNDER CYCLONIC FLOW ALOFT.  
   
LONG TERM
 
(THURSDAY NIGHT THROUGH TUESDAY)  
ISSUED AT 325 AM CDT WED APR 26 2017  
 
HIGH PRESSURE DOES TRY TO BUILD SOUTHEASTWARD AS THE UPPER TROUGH  
CONTINUES TO SLIDE NORTHEAST OF THE REGION LATE IN THE WEEK. THURSDAY  
NIGHT WITH A CHILLY AIR MASS IN PLACE SHOULD SEE TEMPS DOWN IN  
THE LOW 30S AND POSSIBLY 20S, SO FROST MAY BE A CONCERN. AS UPPER  
LEVEL ENERGY DIGS INTO THE DESERT SOUTHWEST, SOUTHWESTERLY FLOW  
ALOFT WILL AMPLIFY ACROSS THE CENTRAL US. AS THIS OCCURS, A  
SHORTWAVE IS FORECAST TO EJECT NORTHEAST ON FRIDAY OUT OF THE  
DEVELOPING TROUGH TO THE WEST. THE 26.00Z GFS AND MOST OF THE GEFS  
MEMBERS, ALONG WITH THE NAM/GEM BRING SOME RAIN INTO AT LEAST  
SOUTHERN PARTS OF THE AREA ON FRIDAY AS THE SHORTWAVE INTERACTS  
WITH A MID-LEVEL FRONTAL ZONE. THE 26.00Z ECMWF REMAINS WEAKER  
WITH THE WAVE AND KEEPS THE AREA MAINLY DRY. KEPT RAIN CHANCES  
GENERALLY ALONG/SOUTH OF I-90 ON FRIDAY.  
 
BEHIND THIS WAVE MUCH OF THE FIRST HALF OF THE WEEKEND MAY BE DRY  
UNDER THE INFLUENCE OF HIGH PRESSURE CENTERED ACROSS SOUTHERN  
CANADA. HOWEVER, TEMPS WILL CONTINUE TO BE BELOW AVERAGE WITH  
HIGHS ON SATURDAY IN THE 50S.  
 
HOWEVER, ANY DRY WEATHER LIKELY WILL BE SHORT-LIVED AS A STRONG  
UPPER SHORTWAVE IS FORECAST TO CLOSE OFF AS IT BEGINS TO LIFT  
NORTHEASTWARD OUT OF THE SOUTHERN PLAINS ON SUNDAY. THE GLOBAL  
OPERATIONAL MODELS HAVE BEEN IN PRETTY GOOD AGREEMENT WITH THIS  
SYSTEM OVER THE PAST FEW DAYS, WITH A SURFACE LOW MOVING TOWARDS THE  
UPPER MISSISSIPPI VALLEY BY SUNDAY NIGHT. CHANCES FOR PRECIP WILL  
INCREASE LATE SATURDAY/SUNDAY AS STRONG LOW-LEVEL WARM/MOIST  
ADVECTION PUSHES NORTH AHEAD OF THE WAVE. WITH THE SYSTEM BECOMING  
STACKED AND POSSIBLY SLOWING, PRECIP MAY LINGER INTO MONDAY.  
THE TRACK OF THE SYSTEM AND HOW MUCH COLD AIR CAN BE WRAPPED INTO  
SYSTEM WILL IMPACT PRECIP TYPE AND AMOUNTS. THERE IS THE  
POSSIBILITY FOR SOME SNOW ON THE WESTERN EDGE OF THE SYSTEM WHERE  
COOLER LOW-LEVEL THERMAL PROFILES ARE MORE LIKELY. THE 26.00Z GFS  
WOULD SUPPORT SOME ACCUMULATING SNOW POTENTIAL INTO SOUTHEAST  
MINNESOTA, BUT IT'S TOO EARLY TO HAVE A HIGH DEGREE OF CONFIDENCE  
ON TRACK/THERMAL PROFILES. IT WILL DEFINITELY BE A SYSTEM TO KEEP  
AN EYE ON LATE THIS WEEK. AT THE LEAST, A CHILLY AND WET PERIOD  
FOR THE END OF THE WEEKEND/EARLY NEXT WEEK LOOKS LIKELY, BEFORE  
THE SYSTEM FINALLY PULLS AWAY EARLY NEXT WEEK AT SOME POINT.  
 

 
   
AVIATION
 
(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)  
ISSUED AT 1147 PM CDT TUE APR 25 2017  
 
LOW CLOUDS CONTINUE TO SLOWLY CREEP EASTWARD, AS LOW PRESSURE  
REMAINS SET TO WORK THROUGH THE REGION OVERNIGHT AND INTO  
WEDNESDAY MORNING. AHEAD OF THAT FEATURE, EXPECT TO SEE SOME BANDS  
OF SHOWERS IMPACTING THE AREA, MOST PRONOUNCED EARLY ON AT RST,  
WITH A SECOND BATCH LIKELY JUST PASSING EAST OF LSE THROUGH MIDDAY  
WEDNESDAY. THE BIGGER STORY REMAINS LOW STRATUS EXPECTED TO  
OVERTAKE THE AREA SLOWLY FROM THE WEST, ESPECIALLY ALONG AND JUST  
BEHIND A PASSING COLD FRONT. AS PREVIOUSLY FORECAST, THE WORST  
CONDITIONS APPEAR IN LINE FOR RST WITH LIFR CEILINGS AND MAYBE  
EVEN A PERIOD OF SOME FOG, WHILE MOSTLY LOWER END MVFR CONDITIONS  
IMPACT LSE. WINDS WILL SWITCH TO THE WEST/NORTHWEST AS THAT FRONT  
PASSES ON WEDNESDAY, WITH SOME GUSTS AROUND 20 KNOTS EXPECTED AT  
TIMES.  
 

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

 
 

 
 
SHORT TERM...JM  
LONG TERM...JM  
AVIATION...LAWRENCE  
 
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