022  
FXUS63 KARX 181658  
AFDARX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE LA CROSSE WI  
1100 AM CST SAT NOV 18 2017  
   
SHORT TERM
 
(TODAY AND TONIGHT)  
ISSUED AT 337 AM CST SAT NOV 18 2017  
 
AT 3 AM, A BAND OF STRONG 700 TO 500 MB FRONTOGENESIS WAS  
PRODUCING RAIN FROM SOUTHEAST NEBRASKA NORTHEAST THROUGH NORTHEAST  
IOWA, EXTREME SOUTHEAST MINNESOTA, AND SOUTHWEST AND CENTRAL  
WISCONSIN. HOURLY RAINFALL AMOUNTS RANGE FROM A TRACE TO 0.05  
INCHES.  
 
THE 18.08Z RAP SHOWS THAT THIS BAND OF FRONTOGENESIS WILL CONTINUE  
TO MOVE SOUTHEAST THIS MORNING AND MOVES OUT OF THE AREA BY  
18.16Z. AS THIS OCCURS, THE PRECIPITATION WILL END ACROSS THE  
AREA. SOUNDINGS SUGGEST AS THE BOUNDARY LAYER COOLS THAT THERE  
WILL BE A MIX OF RAIN AND SNOW. THERE MAY BE A BRIEF PERIOD OF ALL  
SNOW AS THE PRECIPITATION ENDS. SNOW AMOUNTS ACROSS SOUTHWEST  
WISCONSIN AND A SMALL PORTION OF NORTHEAST IOWA WILL RANGE FROM A  
TRACE TO MAYBE A FEW TENTHS OF AN INCH.  
 
IN THE WAKE OF THIS SYSTEM, THE COMBINATION OF A TIGHT SURFACE  
 
PRESSURE GRADIENT AND STEEP 950-900 MB LAPSE RATES WILL RESULT IN  
NORTHWEST WIND GUSTS OF 20 TO 30 MPH. THESE WIND GUSTS WILL  
GRADUALLY DIMINISH THIS EVENING AS THE LOW LEVEL LAPSE RATES  
WEAKEN. WIND CHILLS THIS AFTERNOON WILL RANGE FROM THE TEENS TO  
MID 20S.  
 
ANOTHER SHORT WAVE TROUGH WILL MOVE THROUGH THE REGION TONIGHT.  
THIS SYSTEM WILL PRODUCE MOSTLY CLOUDY SKIES ALONG AND NORTH OF  
THE INTERSTATE 94 CORRIDOR.  
   
LONG TERM
 
(SUNDAY THROUGH FRIDAY)  
ISSUED AT 337 AM CST SAT NOV 18 2017  
 
ON MONDAY, 18.00Z MODELS CONTINUE TO SHOW THAT 925 MB TEMPERATURES  
WILL WARM INTO THE 6 TO 9C IN THE ECMWF AND FROM 4 TO 9C IN THE  
GFS. WITH QUITE A BIT OF SUNSHINE, THE HIGH TEMPERATURES WILL  
LIKELY RANGE FROM THE MID 40S IN NORTH CENTRAL WISCONSIN TO  
AROUND 50 IN SOUTHEAST MINNESOTA AND NORTHEAST IOWA.  
 
ON MONDAY NIGHT, A STRONG CANADIAN COLD FRONT WILL MOVE SOUTHEAST  
THROUGH THE REGION. 925 MB TEMPERATURES WILL DRAMATICALLY COOL AND  
BY TUESDAY AFTERNOON THEY WILL RANGE FROM -5 TO -8C IN THE GFS  
AND -6 AND -9C IN THE ECMWF. HIGH TEMPERATURES WILL RANGE FROM  
THE UPPER 20S TO MID 30S ON TUESDAY AND FROM THE MID 20S TO MID  
30S ON WEDNESDAY.  
 
ON FRIDAY, 925 MB WARM DRAMATICALLY AHEAD OF AN APPROACHING  
SHORTWAVE TROUGH. THE ECMWF HAS THESE TEMPERATURES WARMING INTO  
THE 9 TO 12C RANGE. MEANWHILE, IN THE GFS, THESE TEMPERATURES  
RANGE FROM 9 TO 14C. THE NAEFS 850 MB TEMPERATURE ANOMALIES ARE 1  
TO 2 STANDARD DEVIATIONS JUST TO THE WEST AND SOUTHWEST OF THE  
FORECAST AREA. THE ECMWF HAS HIGH TEMPERATURES RANGING FROM THE  
UPPER 40S TO LOWER 60S. MEANWHILE, THE GFS HAS ITS HIGH  
TEMPERATURES RANGING FROM THE LOWER 40S TO MID 50S. IN BOTH CASES,  
THE WARMEST TEMPERATURES ARE ALONG AND WEST OF THE MISSISSIPPI  
RIVER. SINCE THIS WARMTH HAS BEEN A CONSISTENT SIGNAL IN THE  
MODELS, RAISED THE MAXIMUM TEMPERATURES 5 TO 10F ABOVE THE MODEL  
CONSENSUS.  
 

 
   
AVIATION
 
(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)  
ISSUED AT 1100 AM CST SAT NOV 18 2017  
 
CIGS: LOW CIGS ARE QUICKLY VACATING TO THE EAST AT LATE MORNING. MID  
LEVEL TROUGH COULD BRING A FEW HOUR PERIOD OF VFR CIGS FOR LATE  
AFTERNOON/EVENING...OTHERWISE EXPECT SKC/SCT CONDITIONS THROUGH  
SUNDAY MORNING.  
 
WX/VSBY: NO IMPACTS EXPECTED AT THIS TIME.  
 
WINDS: TIGHT PRESSURE GRADIENT WILL KEEP WINDS "UP" AND GUSTY INTO  
THIS EVENING, RELAXING OVERNIGHT/SUNDAY AS HIGH PRESSURE INFLUENCES  
FROM THE SOUTH. DIRECTION WILL HOLD MOSTLY NORTHWEST INTO SUN  
MORNING, GRADUALLY TRANSITIONING TO THE SOUTH AS THE HIGH PRESSURE  
RIDGE MOVES EAST.  
 

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

 
 

 
 
SHORT TERM...BOYNE  
LONG TERM...BOYNE  
AVIATION...RIECK  
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab WI Page
The Nexlab IA Page
The Nexlab MN Page Main Text Page