155  
FXUS63 KARX 172351  
AFDARX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE LA CROSSE WI  
651 PM CDT SAT APR 17 2021  
   
SHORT TERM
 
(TONIGHT THROUGH TUESDAY)  
ISSUED AT 100 PM CDT SAT APR 17 2021  
 
UPPER LEVEL SHORTWAVE TROUGH STILL ON THE DOCKET TO SLIDE SOUTHEAST  
ACROSS THE REGION OVERNIGHT SUNDAY THROUGH MONDAY WITH AN ASSOCIATED  
COLD FRONT OUT AHEAD OF IT. SLOPING FRONTOGENETIC LIFT ACROSS THE  
BOUNDARY, BUT SATURATION HANGS BEHIND THE FRONT (PER BUFKIT  
SOUNDINGS/TIME-HEIGHT X-SECTIONS) - THUS, SO DOES THE ASSOCIATED  
SHOWER CHANCES. WITH MUCH COLDER AIR FLOWING IN BEHIND THE FRONT,  
THERE WILL BE BOTH RAIN AND SNOW CHANCES - ALTHOUGH NOT EXPECTING  
MUCH/IF ANY SNOW ACCUM AT THIS TIME.  
 
OF POTENTIALLY MORE CONCERN IS HOW FAR SOUTH THE FRONT SAGS TUE.  
ANOTHER PIECE OF UPPER LEVEL ENERGY IS PROGGED TO ROTATE OUT OF THE  
SOUTHERN ROCKIES AND RIDE ALONG THE FRONT. MEANWHILE, 300 MB JET  
STREAK PROMISES TO ENHANCE THE LIFT VIA THE RIGHT ENTRANCE REGION.  
END RESULT IS A PCPN BAND DEVELOPING ALONG/NORTH OF THE FRONT...AND  
WITH PLENTY OF COLD AIR IN PLACE...COULD/WOULD BE MOSTLY SNOW. IN  
FACT, SOMEONE(S) COULD GET SIGNIFICANT AMOUNTS, ESPECIALLY  
CONSIDERING IT'S MID APRIL. THE OPERATIONAL RUN OF THE GFS HOLDS THE  
PCPN BAND SOUTH OF THE LOCAL AREA WHILE THE EC BRUSHES PARTS OF NE  
IA/SW WI. GFS ENSEMBLE MEMBERS KIND OF A MESS WHILE AROUND 1/2 OF  
THE EC'S LIKES THE MORE NORTHWARD SOLUTION. THE 17.12Z NAM FAVORS  
THE EC NORTHWARD TAKE TOO. FOR NOW, WILL RUN WITH THE MODEL BLEND  
FOR POPS. GOING TO HAVE TO WATCH THIS ONE CLOSE - COULD EASILY SEE A  
FEW INCHES...OR NONE. SNOW WOULDN'T STICK AROUND LONG.  
 
MEANWHILE, TEMPS TAKE A TUMBLE STARTING MONDAY, WITH THE COLDEST AIR  
SETTLING IN FOR TUE (HIGHS COULD STRUGGLE TO REACH 40). 850 MB TEMPS  
AS COLD AS -8 C WITH NAEFS 850 MB TEMP ANOMALIES STILL -1 OR LOWER.  
IF YOU GOT AN EARLY START TO SPRING PLANTING, BE READY TO TAKE SOME  
PRECAUTIONS - FREEZING TEMPS ARE EXPECTED TUE/WED MORNINGS.  
 
WINTER ISN'T DONE WITH US YET.  
   
LONG TERM
 
(WEDNESDAY THROUGH SATURDAY)  
ISSUED AT 100 PM CDT SAT APR 17 2021  
 
SOMEWHAT MESSY UPPER LEVEL PATTERN FOR THE LATER HALF OF THE NEW  
WEEK WITH A VARIETY OF POTENTIAL OUTCOMES VIA THE GFS AND EC - BOTH  
IN THE OPERATIONAL RUNS AND THROUGH THEIR RESPECTIVE ENSEMBLE  
MEMBERS. THAT SAID, A FEW POINTS THERE SEEMS TO BE SOME AGREEMENT  
ON. FIRST IS FOR SHORTWAVE RIDGING/SFC HIGH FOR THU/FRI...WITH A  
SLIGHT (TEMPORARY) BUMP UP IN TEMPS. SECOND WOULD BE AN UPPER LEVEL  
SHORTWAVE TROUGH THEN DROPPING ACROSS THE AREA SAT/SAT NIGHT  
BRINGING SOME PCPN CHANCES (QPF FAIRLY LIGHT). AGAIN, CONFIDENCE ON  
THE LOW END IN THE DETAILS BUT WILL LEAN THE FORECAST TOWARD THESE  
CURRENT TRENDS.  
 
AS FOR WHEN WE'LL SAY GOODBYE TO THE COOL CONDITIONS - THE 8 TO 14  
DAY OUTLOOK FROM CPC DOESN'T BRING MUCH HOPE, KEEPING THE REGION  
UNDER THE HIGHER LIKELIHOOD TO STAY COLD. THAT SAID, THE EC AND GFS  
(ESPECIALLY THE GFS) SHOWING SIGNS OF RIDGE BUILDING TO THE WEST FOR  
THE LAST WEEK OF APRIL - GRADUALLY PUSHING EASTWARD. CROSS YOUR  
FINGERS.  
 

 
   
AVIATION
 
(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)  
ISSUED AT 641 PM CDT SAT APR 17 2021  
 
VFR CONDITIONS THROUGH THE PERIOD. A SHORTWAVE WILL BRING  
INCREASING MID CLOUDS FL080 THIS EVENING. A STRONGER FRONT WILL  
ARRIVE LATER SUNDAY. AHEAD OF THIS STRONGER FRONT SUNDAY, LOOK  
FOR HIGH CLOUDS AND MID CLOUDS FL100 TO THICKEN WITH RAIN CHANCES  
BEGINNING WITH THE NEXT TAF ISSUANCE. NORTHWEST WINDS DECREASE  
TONIGHT WITH THE FLOW BECOMING WEST SOUTHWEST AT KRST. AHEAD OF  
THE FRONT, WEST WINDS INCREASE 10 TO 15KTS WITH GUSTS 20 TO 25KTS  
AT KRST AS THEY SHIFT TO THE NORTHWEST.  
 

 
   
FIRE WEATHER
 
 
ISSUED AT 100 PM CDT SAT APR 17 2021  
 
ANOTHER DAY OF DEEP MIXING SUNDAY, UPWARDS OF 800 MB PER NAM12  
BUFKIT SOUNDINGS. DEWPOINTS ALREADY RELATIVELY LOW THOUGH, SO IMPACT  
OF THE MIXING ON DRYING COULD BE COMPARATIVELY SMALL. THAT SAID,  
STILL LOOKING AT WIDESPREAD MIN RHS IN THE 20 PERCENTS DURING THE  
AFTERNOON.  
 
IN ADDITION, NOT A LOT OF WIND TO BRING TO THE SURFACE, SO WHILE  
WINDS SHOULD BE A FEW TICKS STRONGER ON SUNDAY COMPARED TO TODAY,  
GUSTS ONLY IN THE MID TEENS ARE ANTICIPATED.  
 

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

 
 

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

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