638  
FXUS63 KARX 222045  
AFDARX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE LA CROSSE WI  
245 PM CST WED JAN 22 2020  
   
SHORT TERM
 
(THIS AFTERNOON INTO TONIGHT)  
ISSUED AT 245 PM CST WED JAN 22 2020  
 
THE UPPER-LEVEL SHORTWAVE TROUGH IS PROGGED TO LIFT NORTH INTO THE  
AREA TODAY/TONIGHT, BRINGING WITH IT CONTINUED CHANCES FOR ON AND  
OFF WINTRY PRECIPITATION. INDICATIONS POINT TO MOSTLY SNOW, BUT  
UNTIL TEMPERATURES COOL ALOFT, THERE COULD BE SOME BRIEF PERIODS OF  
WINTRY MIX (RAIN, ICE PELLETS, AND/OR FREEZING DRIZZLE) AT TIMES.  
ADDITIONAL SNOW ACCUMULATIONS FROM LATE THIS AFTERNOON INTO TONIGHT  
WILL BE RATHER LIGHT, RANGING FROM 1 TO 2 INCHES. SOME LOCALLY  
HIGHER AMOUNTS WILL BE POSSIBLE, MAINLY ACROSS WESTERN AND NORTH-  
CENTRAL WISCONSIN WHERE A BAND OF SNOW HAS BEEN FALLING THIS  
AFTERNOON. AS THE CENTER OF THE SURFACE LOW WORKS ITS WAY INTO THE  
AREA LATER TONIGHT, WINDS SHOULD LIGHTEN UP, ESPECIALLY WEST OF THE  
MISSISSIPPI RIVER. THIS PAIRED WITH FRESH A SNOWPACK MAY LEAD TO  
SOME PATCHY FOG DEVELOPMENT LATE TONIGHT INTO THURSDAY MORNING. HAVE  
ADDED THE MENTION OF PATCHY FOG TO THE FORECAST TO REFLECT THIS.  
   
LONG TERM
 
(THURSDAY THROUGH WEDNESDAY)  
ISSUED AT 245 PM CST WED JAN 22 2020  
 
A BIT OF A CONVOLUTED PATTERN EVOLUTION THE NEXT 48 HOURS,  
CONTINUING VARIOUS WINTRY WEATHER CHANCES ACROSS MUCH OF THE AREA  
BUT WITH SOMEWHAT LOWER CONFIDENCE ON EXACTLY WHAT TYPE(S) OF  
PRECIPITATION WILL OCCUR FOR ANY GIVEN AREA AT ANY SPECIFIC TIME. AS  
DISCUSSED ABOVE, LEAD SHORTWAVE CHURNING NORTHWARD THROUGH IOWA  
TODAY WILL CROSS THE LOCAL AREA TONIGHT, BUT THE NEXT FOCUS WILL BE  
ADDITIONAL SHORTWAVE ENERGY EXITING THE NORTHERN ROCKIES AND DIVING  
THROUGH THE CENTRAL PLAINS TONIGHT. THAT FEATURE (AND ANOTHER WAVE  
QUICKLY ON ITS HEELS) IS EXPECTED TO CLOSE OFF QUICKLY OVER THE MID  
MISSISSIPPI VALLEY AS THE STRONG DRIVING JET ENERGY COLLAPSES, WITH  
THAT CLOSED FEATURE VERY SLOWLY MEANDERING INTO THE LOWER GREAT  
LAKES BY SATURDAY.  
 
PLACEMENT OF THE UPPER LOW JUST TO THE SOUTH WILL MAINTAIN PERIODS  
OF LOW/MID LEVEL WARM ADVECTION ASCENT OVER MUCH OF THE AREA  
THURSDAY INTO FRIDAY, COMPLEMENTED AT TIMES BY MID LEVEL DEFORMATION  
ON THE NORTHERN FRINGE OF THE CLOSED WAVE. THAT SETUP WILL MAINTAIN  
ADDITIONAL ROUNDS OF PRECIPITATION BEFORE FORCING FINALLY FADES INTO  
FRIDAY AFTERNOON/EVENING, THOUGH THE EXACT TYPE REMAINS PROBLEMATIC  
AT TIMES GIVEN LOSS OF CLOUD ICE AND SOME DEGREE OF A WARMER  
BOUNDARY LAYER AT TIMES AS TEMPERATURES (ESPECIALLY DURING THE DAY)  
FLIRT WITH THE MID OR UPPER 30S IN SOME SPOTS. ALL TOLD, SUSPECT  
MUCH OF THE PRECIPITATION WILL SIMPLY BE SNOW, ESPECIALLY WITH A  
LACK OF ANY RESIDUAL WARM NOSE ALOFT (MUCH OF THE COLUMN BELOW 0C),  
THOUGH AGAIN WE MAY NOT SEE MUCH ACCUMULATION DURING THE DAY GIVEN  
THE WARMER BOUNDARY LAYER. HOWEVER, STILL DO EXPECT TO SEE SOME  
OVERALL LIGHT ACCUMULATION IN MANY AREAS, WITH MAINLY MINOR IMPACTS  
GIVEN THE RELATIVELY "WARM" REGIME.  
 
THEREAFTER, QUIETER WEATHER SHOULD MAKE A WELCOME RETURN INTO THE  
WEEKEND AND EARLY NEXT WEEK AS WE GRADUALLY LOSE THE LOW/MID LEVEL  
CYCLONIC FLOW AND IT IS REPLACED BY TRANSIENT SHORTWAVE RIDGING BY  
MONDAY OR TUESDAY. HOWEVER, UNFORTUNATELY THE PATTERN DOESN'T LOOK  
OVERLY SUNNY, WITH A QUICK PERUSAL OF TIME HEIGHTS AND FORECAST  
SOUNDINGS STRONGLY SUGGESTIVE OF BOUNDARY LAYER MOISTURE TRAPPED  
BENEATH A BUILDING INVERSION, WHICH ALSO FITS THE WARMER PATTERN  
WITH SOME MELTING SNOW EXPECTED. SPEAKING OF THAT WARM, DESPITE THE  
CLOUDIER CONDITIONS, TEMPERATURES LOOK TO REMAIN QUITE A BIT ABOVE  
NORMAL AS MILDER PACIFIC AIR CONTINUES TO FLOOD MUCH OF THE CONUS,  
WITH SOME CHANCE THAT HIGHS WILL PUSH 40 BY THE EARLY WORK WEEK,  
THOUGH DEPENDENT TO SOME DEGREE ON CLOUD COVER (I.E. COULD END UP A  
LITTLE COOLER THAN EXPECTED AT TIMES). OTHERWISE, BY MID TO LATE  
WEEK THERE ARE INCREASING SIGNALS FOR YET ANOTHER CLOSED LOW TO  
MEANDER SOMEWHERE ACROSS THE REGION, THOUGH WE'LL CROSS THAT BRIDGE  
OVER THE COMING DAYS AS DETAILS BECOME A LITTLE MORE CLEAR.  
 

 
   
AVIATION
 
(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)  
ISSUED AT 1146 AM CST WED JAN 22 2020  
 
A TRICKY FORECAST OVER THE NEXT 24 HOURS, WITH A LONG DURATION OF  
WINTRY PRECIPITATION LIFTING NORTH OVER THE LOCAL AREA. A LITTLE BIT  
OF A LULL EXPECTED EARLY THIS AFTERNOON AT BOTH TAF SITES, WITH  
ANOTHER ROUND OF MORE PERSISTENT SNOW AND VISIBILITY REDUCTIONS BY  
LATER THIS AFTERNOON/EVENING. AS OF NOW, IT LOOKS LIKE THE LOWER  
VISIBILITY RESTRICTIONS SHOULD IMPROVE SOME BY LATE THIS EVENING  
AS THE BAND OF SNOW EXITS. CEILINGS WILL GRADUALLY LOWER OVERNIGHT  
INTO THURSDAY, WITH LIFR POSSIBLE, MAINLY AT KRST. SOUTH WINDS  
BETWEEN 10- 15 KTS TO CONTINUE THROUGH THE REMAINDER OF THE  
DAYLIGHT HOURS TODAY BEFORE LESSENING OVERNIGHT.  
 

 
   
ARX WATCHES/WARNINGS/ADVISORIES
 
 
WI...WINTER WEATHER ADVISORY UNTIL 9 PM CST THIS EVENING FOR WIZ017-  
029-032>034.  
 
MN...WINTER WEATHER ADVISORY UNTIL 9 PM CST THIS EVENING FOR MNZ079-  
086>088-094-095.  
 
IA...WINTER WEATHER ADVISORY UNTIL 9 PM CST THIS EVENING FOR IAZ008-  
009-018-019.  
 

 
 

 
 
SHORT TERM...NMB  
LONG TERM...LAWRENCE  
AVIATION...NMB  
 
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