743  
FXUS63 KDVN 111149  
AFDDVN  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE QUAD CITIES IA IL  
549 AM CST SUN DEC 11 2016  
   
..12Z AVIATION UPDATE
 
 
   
SYNOPSIS
 
 
ISSUED AT 323 AM CST SUN DEC 11 2016  
 
SNOW EVENT ONGOING, BUT OVERNIGHT TRENDS SUGGEST BRUNT OF BEST  
FORCING AND THUS SNOWFALL HAS SHIFTED EVEN FURTHER NORTH ACRS FAR  
SOUTHERN MN, FAR NORTHEASTERN IA AND INTO WI. THE NEXT LOW PRESSURE  
CENTER THAT WILL ROLL UP TOWARD THE AREA AND BRING WARMER AIR IN THE  
SOUTH, TAKING SHAPE ACRS THE SOUTHWESTERN PLAINS.  
 

 
   
SHORT TERM
 
(TODAY AND TONIGHT)  
ISSUED AT 323 AM CST SUN DEC 11 2016  
 
ONGOING SNOWS FROM THE EASTERN DAKOTAS, SOUTHEASTWARD ALONG THE  
MN/IA BORDER INTO THE NORTHERN THIRD OF IL AND SOUTHERN WI, WILL  
MOVE OUT OF THE NORTHERN AND NORTHEASTERN CWA, OR AT LEAST DIMINISH  
AFTER 5 OR 6 AM. THEN AS THE LOW PRESSURE AND INVERTED TROF SYSTEM  
ROLLS UP ACRS THE MID TO UPPER MS RVR VALLEY THROUGH THIS AFTERNOON,  
MORE PRECIP AND POSSIBLY A DEF ZONE TYPE BAND OF PRECIP WILL TAKE  
SHAPE ACRS MORE OF THE SOUTHEASTERN HALF TO 2/3'S OF THE CWA FROM  
LATE MORNING AND INTO THE AFTERNOON, BEFORE SHIFTING EAST OF THE CWA  
THIS EVENING. ALL IN ALL, LATEST THINKING WITH SNOWFALL AMOUNTS OF 1-  
3 INCHES THAT HAVE ALREADY FALLEN NORTH OF I80, AND SYSTEM TRENDS  
WITH ADDITIONAL PROJECTIONS SUGGEST THAT JUST WINTER WEATHER ADVISORY  
HEADLINES WARRANTED AND MAINLY EAST OF AN IOWA CITY TO DUBUQUE  
LINE...THE WARNING AREAS MARGINAL AT BEST.  
 
NEW SNOWFALL AMOUNTS AFTER 12Z SUNDAY WEST OF THE MS RVR AND NORTH  
OF I80 ONLY HALF INCH TO AN INCH, WHILE AREAS EAST OF THE MS RVR AND  
ALONG/NORTH OF I80 GET ANOTHER 1-2+ INCHES TODAY. AREAS ALONG AND  
SOUTH OF I80, WITH WARMING PROFILES BEING PULLED UP ACRS THE AREA BY  
THE INCOMING SYSTEM AND SOUTHERLY LOW TO MID LEVEL FLOW WILL MAKE  
FOR MIXED PRECIP ACRS THOSE AREAS. THINKING RAIN-SNOW MIX TRENDING  
TO MAINLY A COLD RAIN, WITH BOUTS OF SLEET FROM TIME TO TIME. THIS  
WILL MAKE IT TOUGH FOR ANY SNOW TO ACCUMULATE IN THOSE AREAS TODAY.  
WARMING SFC TEMPS OVER COLD GROUND AND SNOW COVER, AND POSSIBLE  
CONVERGENT FLOW MAY ALLOW FOR SOME AREAS OF FOG TO FORM THROUGH THE  
DAY, UNTIL NORTHWEST POST-SYSTEM FLOW INCREASES THIS EVENING. BUT  
WITH COMPLEXITY OF THE FCST, WILL LEAVE OUT MENTION FOR NOW. THE  
CURRENT PHILOSOPHY WILL KEEP THE CURRENT HEADLINES GOING FOR NOW  
WHILE IT IS STILL SNOWING, BUT THEN START TO TRIM FROM THE WEST  
AFTER 5 OR 6 AM THIS MORNING, AS WELL AS HAVING TO ASSESS TRENDING  
THE WARNING AREAS IN NW IL TO ADVISORY. WILL PROBABLY KEEP AT LEAST  
THE EASTERN HALF TIER OF THE ADVISORY GOING FOR THE SNOW LATER TODAY  
WHEN PEOPLE ARE OUT AND ABOUT FOR SLICK ROADS AND REDUCED VISIBILITY,  
ALTHOUGH THOSE PARAMETERS MAY BE MARGINAL AS WELL. ALL PRECIP WINDING  
DOWN EARLY THIS EVENING. ..12..  
   
LONG TERM
 
(MONDAY THROUGH NEXT SATURDAY)  
ISSUED AT 323 AM CST SUN DEC 11 2016  
 
THE EXTENDED REMAINS COLD, AND MARGINALLY ACTIVE WITH POSSIBLE LIGHT  
SNOW WITH ANY PASSING WAVE THOUGH THE ARCTIC AIR. THERE HAVE BEEN  
PROBLEMS WITH MODEL BLENDS TONIGHT, BUT THE OVER ALL TRENDS ARE  
REFLECTED IN THE GRIDS AS BEST CAN BE COLLABORATED.  
 
FOR THE EARLY TO LATE WORK WEEK, WE WILL HAVE SNOW COVER OVER  
ROUGHLY THE NORTH 1/2 OF THE CWA, AND LIKELY BARE GROUND SOUTH.  
THUS, THERE WILL BE A TEMPERATURE CHALLENGE DAY AND NIGHT, WITH  
TRUE ARCTIC COLD OVER THE NORTH, AND A MODIFIED AIRMASS IN THE  
SOUTH. BELOW ZERO LOWS ARE LIKELY OVER SNOW, WHILE THE SOUTH SEE 5  
TO 15 FOR LOWS. THE NEXT SYSTEM WILL SPREAD WARM ADVECTION SNOW  
OVER THE MIDWEST AGAIN BY FRIDAY, LASTING POSSIBLY INTO SATURDAY.  
MODELS HAVE SHIFTED THIS LOW WELL NORTH OF ANY TRACK INDICATED 24  
HOURS AGO, MAKING P-TYPE QUESTIONS ENTER INTO THE CHALLENGES FOR  
LATE WEEK. FOR NOW, THAT SYSTEM LOOKS VERY PROGRESSIVE AND ANY MIX  
OR RAIN COULD BE VERY SHORT LIVED BEFORE A DRY SLOT ARRIVES, THUS  
IT IS NOT WORTH TIMING A 2-4 HOUR WINDOW OF LOW CONFIDENCE MIX IN  
ON DAY 6. WE CAN APPROACH THAT POTENTIAL CHALLENGE AFTER THIS  
STORM SYSTEM IN THE SHORT TERM GETS OUT OF THE REGION.  
 
ERVIN  
 

 
   
AVIATION
 
(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)  
ISSUED AT 531 AM CST SUN DEC 11 2016  
 
WITH OVERNIGHT BANDS OF SNOW MOVING OUT OF THE AREA CURRENTLY,  
THERE WILL BE A TEMPORARY LULL AND VFR PERIOD THRU MID MORNING.  
THEN THE NEXT SYSTEM WILL LIFT UP TOWARD THE AREA OUT OF THE  
CENTRAL PLAINS AND BRING LOWERING CIGS AND MORE PRECIP TO THE  
AREA FROM LATE MORNING AND INTO THE AFTERNOON. SNOW ALONG AND  
NORTH OF I80, AND RAIN-SNOW MIX POSSIBLY GOING OVER TO ALL RAIN  
FOR A PERIOD SOUTH OF I80 AT BRL. THE HEAVIER SNOW/IFR TO LIFR  
CONDITIONS MAY HAVE THE BEST CHANCE TO SET UP MIDDAY THROUGH MID  
AFTERNOON ALONG THE I80 CORRIDOR AND EFFECT THE MLI TERMINAL.  
LIGHTER SNOW THEN WITH MVFR TO IFR CONDITIONS AT TIMES FOR CID  
AND DBQ THIS AFTERNOON UNTIL EARLY EVENING WHEN THE PRECIP IS THEN  
EXPECTED TO MOVE OFF TO THE EAST. LIGHTER SOUTH WINDS AND MILDER  
AIR OVER COLD GROUND MAY PRODUCE ROUNDS OF MVFR TO LIFR FOG TODAY  
EVEN WHEN PRECIP IS NOT FALLING. INCREASING WEST TO NORTHWEST  
WINDS FROM WEST-TO-EAST LATER THIS EVENING WILL HELP SCOOP UP  
CIGS SOME AND IMPROVE VSBYS. ..12..  
 

 
   
DVN WATCHES/WARNINGS/ADVISORIES
 
 
IA...WINTER WEATHER ADVISORY UNTIL 6 PM CST THIS EVENING FOR BENTON-  
CEDAR-CLINTON-JOHNSON-JONES-LINN-MUSCATINE-SCOTT.  
 
WINTER STORM WARNING UNTIL 6 PM CST THIS EVENING FOR BUCHANAN-  
DELAWARE-DUBUQUE-JACKSON.  
 
IL...WINTER WEATHER ADVISORY UNTIL 6 PM CST THIS EVENING FOR BUREAU-  
HENRY IL-PUTNAM-ROCK ISLAND-WHITESIDE.  
 
WINTER STORM WARNING UNTIL 6 PM CST THIS EVENING FOR CARROLL-JO  
DAVIESS-STEPHENSON.  
 
MO...NONE.  

 
 

 
 
SYNOPSIS...12  
SHORT TERM...12  
LONG TERM...ERVIN  
AVIATION...12  
 
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