358  
FXUS63 KARX 231117  
AFDARX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE LA CROSSE WI  
617 AM CDT SAT OCT 23 2021  
   
SHORT TERM
 
(TODAY AND TONIGHT)  
ISSUED AT 244 AM CDT SAT OCT 23 2021  
 
A DEEP UPPER LOW RETROGRADING FROM JAMES BAY TODAY IS KEEPING CHILLY  
CYCLONIC FLOW OVER THE REGION. EARLY MORNING WATER VAPOR IMAGERY  
REVEALS A SHORTWAVE DROPPING THROUGH THE UPPER MISSISSIPPI VALLEY,  
SUPPORTING VARIABLE CLOUDINESS OVER PORTIONS OF WISCONSIN. THESE  
CLOUDS HAVE INTRODUCED SOME TEMPERATURE FORECAST COMPLEXITIES, WITH  
TEMPS UNDERNEATH HOLDING A BIT WARMER. TEMPS OUTSIDE THE CLOUD COVER  
STILL LOOK ON TRACK FOR DIPPING INTO THE UPPER 20S BY DAYBREAK. ALSO  
SOME VALLEY FOG/STRATUS SHOWING UP ON SATELLITE IN THE MAIN  
MISSISSIPPI CHANNEL SOUTH OF LA CROSSE AS WELL AS THE WISCONSIN.  
 
CLOUDS ARE EXPECTED TO LINGER OVER AREAS NEAR AND NORTH OF I-94 INTO  
THIS AFTERNOON, WITH CIRRUS ALSO INCREASING FROM THE WEST. QUIET  
OVERALL AS SURFACE RIDGE AND BAGGY PRESSURE GRADIENT DRIFT OVER THE  
AREA, RESULTING IN LIGHT NORTH TO NORTHEAST WINDS AND HIGHS IN THE  
UPPER 40S TO MID 50S.  
 
WILL BE WATCHING A DEVELOPING SYSTEM OVER THE CENTRAL PLAINS HEADING  
INTO TONIGHT AS A PRONOUNCED UPPER TROUGH CROSSES THE FOUR CORNERS  
REGION. THE RESULTANT DEEPENING SURFACE LOW WILL SET UP A TIGHT  
BAROCLINIC ZONE TO OUR SOUTH HEADING INTO SUNDAY. DEVELOPING  
ISENTROPIC ASCENT NORTH OF A WARM FRONT FROM EASTERN KS TO  
SOUTHERN OH WILL BEGIN TO SPREAD NORTHWARD INTO OUR AREA LATE  
TONIGHT. EXPECT THICKENING CLOUD COVER AS A RESULT, THOUGH RAIN  
CHANCES SHOULD LARGELY HOLD OFF UNTIL DAYTIME.  
   
LONG TERM
 
(SUNDAY THROUGH FRIDAY)  
ISSUED AT 244 AM CDT SAT OCT 23 2021  
 
THE NEGATIVELY TILTED, STRENGTHENING SYSTEM WILL CREEP INTO WESTERN  
IOWA ON SUNDAY. MEANWHILE THERE WILL BE A PRETTY STRONG HIGH  
PRESSURE SYSTEM AND ASSOCIATED DRY AIRMASS ANCHORED OVER HUDSON BAY  
INTO MONDAY. THIS WILL AID IN KEEPING THE SYSTEM'S MOST SUBSTANTIAL  
RAINFALL JUST SOUTH OF OUR AREA. IN FACT, THE BIGGEST FORECAST  
QUESTION REMAINS JUST HOW FAR NORTH RAIN CHANCES WILL EXTEND. IT  
DOES LOOK LIKE SOME BANDS OF FRONTOGENESIS WILL LIFT AS FAR  
NORTHWARD AS I-94 SUNDAY INTO MONDAY MORNING, WITH PWATS INCREASING  
TO 0.75 TO 1+ INCHES -- A FAVORABLE SETUP FOR SOME NEEDED RAINFALL  
FOR MUCH OF THE AREA. PRETTY STRONG MODEL CONSENSUS FOR I-90 BEING  
THE GENERAL NORTHWARD EXTENT OF THE RAIN SHIELD. EPS CONTINUES TO  
SHOW GOOD RUN-TO-RUN CONSISTENCY WITH I-90 AS THE NORTHWARD EXTENT  
(AND CAMS SEEM TO BE INDICATING THE SAME). ON THE OTHER HAND, GEFS  
HAS BEEN MORE ERRATIC BUT STILL THE FURTHEST NORTH SOLUTION WITH  
RAIN NOW WELL INTO NORTH-CENTRAL WI. REGARDLESS, CONSENSUS FAVORS  
AROUND 0.5 TO JUST SHY OF 1" OF RAINFALL SOUTH OF I-90 BEFORE RAIN  
QUICKLY EXITS MONDAY MORNING. COULD BE A FEW RUMBLES OF THUNDER IN  
OUR FAR SOUTHERN COUNTIES. THE OTHER THING OF NOTE WILL BE AN  
INCREASE IN WINDS SUNDAY AFTERNOON INTO THE OVERNIGHT AS THE  
INTENSIFYING SURFACE LOW PASSES BY TO OUR SOUTH. 925MB WINDS WILL BE  
STRONGEST SOUTH OF I-90, INCREASING TO 35-40 KNOTS. THUS, EXPECT  
GUSTS OF 25-35 MPH AREA WIDE, STRONGEST SOUTH OF I-90 WHERE A FEW  
GUSTS COULD APPROACH 40 MPH. FORECAST SOUNDINGS SHOW BOUNDARY LAYER  
MIXING CONTINUING AFTER DARK, SO WINDY CONDITIONS ARE EXPECTED TO  
PERSIST OVERNIGHT.  
 
ATTENTION THEN TURNS TO ANOTHER SYSTEM TOWARDS MID-WEEK AS DEEP  
TROUGHING CROSSES THE WESTERN CONUS. CONSIDERABLE FORECAST  
UNCERTAINTY AS MODELS CONTINUE TO SHOW VARIOUS OUTCOMES ONCE THIS  
TROUGH CROSSES THE ROCKIES. ECMWF AND CMC DEVELOP SPLIT UPPER FLOW  
WITH A SOUTHERN-STREAM CUTOFF LOW AND NORTHERN STREAM SHORTWAVE THAT  
EVENTUALLY PHASE EAST OF THE MISSISSIPPI RIVER THURSDAY INTO FRIDAY.  
MEANWHILE GFS DEVELOPS A DEEP CUTOFF LOW OVER THE MID-MISSISSIPPI  
VALLEY BY THURSDAY. WILL ALSO HAVE SOME DRY AIR TO CONTEND WITH  
LOCALLY AS THIS SYSTEM APPROACHES, SO CONFIDENCE IN PRECIP CHANCES  
IS LOW TO MEDIUM FROM TUESDAY NIGHT AND BEYOND. STILL LOOKS LIKE A  
DECENT SETUP FOR RAIN, BUT AMOUNTS AND COVERAGE ARE STILL VERY MUCH  
UNCERTAIN. TEMPERATURE-WISE, NO SIGNIFICANT WARM UPS ARE EXPECTED  
OVER THE UPCOMING WEEK.  
 

 
   
AVIATION
 
(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)  
ISSUED AT 617 AM CDT SAT OCT 23 2021  
 
LATEST NIGHTTIME SATELLITE IMAGERY SHOWS FOG/LOW STRATUS FORMATION  
IN THE MISSISSIPPI RIVER VALLEY THIS MORNING. AT THIS TIME...THE  
FOG/LOW STRATUS REMAINS SOUTH/NORTH OF THE KLSE TAF SITE AND IFR  
CEILINGS/VISIBILITY CONDITIONS WOULD BE VERY BRIEF AT THE KLSE TAF  
SITE EARLY IN THE TAF PERIOD. HAVE INTRODUCED BCFG AT KLSE TAF  
SITE FOR A COUPLE OF HOURS EARLY IN THE TAF PERIOD. VFR  
CONDITIONS WILL PREVAIL THROUGH THE TAF PERIOD WITH SURFACE RIDGE  
IN CONTROL OVER THE UPPER GREAT LAKES REGION TODAY AND INTO  
TONIGHT. A STORM SYSTEM WILL MOVE INTO THE CENTRAL PLAINS STATES  
AFTER 06Z SUNDAY AND SPREAD SOME MID TO HIGH CLOUDS LATE IN THE  
TAF PERIOD. CEILINGS SHOULD REMAIN IN VFR.  
 

 
   
ARX WATCHES/WARNINGS/ADVISORIES
 
 
WI...FREEZE WARNING UNTIL 9 AM CDT THIS MORNING FOR WIZ041-053>055-  
061.  
 
MN...FREEZE WARNING UNTIL 9 AM CDT THIS MORNING FOR MNZ087-088-  
094>096.  
 
IA...FREEZE WARNING UNTIL 9 AM CDT THIS MORNING FOR IAZ008>011-018-  
019-029-030.  
 

 
 

 
 
SHORT TERM...KURZ  
LONG TERM...KURZ  
AVIATION...DTJ  
 
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