731  
FXUS63 KDVN 181126  
AFDDVN  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE QUAD CITIES IA IL  
526 AM CST FRI JAN 18 2019  
   
..12Z AVIATION UPDATE
 
 
   
SYNOPSIS
 
 
ISSUED AT 320 AM CST FRI JAN 18 2019  
 
CANADIAN HIGH PRESSURE WAS CENTERED OVER THE UPPER MIDWEST EARLY  
THIS MORNING. THE SURFACE RIDGE AXIS IS BUILDING INTO THE AREA  
PROVIDING THE PROVERBIAL CALM BEFORE THE STORM, WITH EVEN SOME  
DECREASE IN STRATUS NOTED ACROSS PORTIONS OF NORTHEAST AND EAST  
CENTRAL IOWA. MEANWHILE, THE UPPER LEVEL SHORTWAVE SET TO BRING  
ACCUMULATING SNOW TO THE REGION OVER THE NEXT 24+ HOURS IS  
CURRENTLY PROGRESSING THROUGH THE ROCKIES.  
 

 
   
SHORT TERM
 
(TODAY THROUGH SATURDAY)  
ISSUED AT 320 AM CST FRI JAN 18 2019  
 
BOTTOM LINE UP FRONT...  
 
HAVE UPGRADED THE REST OF THE WINTER STORM WATCH TO A WINTER STORM  
WARNING. DECISION TO UPGRADE WAS BASED LARGELY ON IMPACTS RATHER  
THAN CRITERIA WARNING AMOUNTS.  
 
SNOWFALL TIMING... CONFIDENCE IS MODERATE. SEEING A LITTLE SLOWING  
OF THE FORCING AND SATURATION. IN GENERAL, STILL EXPECTING SNOW TO  
DEVELOP NORTH/WEST OF QUAD CITIES THIS AFTERNOON AND LASTLY INTO  
OUR FAR EAST/SOUTHEAST COUNTIES BY EARLY EVENING. SNOW CONTINUES  
OVERNIGHT TAPERING OFF FROM NW TO SE LATE TONIGHT THROUGH  
MID MORNING SATURDAY.  
 
SNOWFALL AMOUNTS... CONFIDENCE IS MODERATE. ACCUMULATIONS ARE  
FORECAST IN THE RANGE OF 4-8 INCHES, WITH THE HIGHER AMOUNTS  
LIKELY FOCUSING IN A BAND(S) NORTH/WEST-SOUTHWEST OF THE QC METRO.  
 
WINDS... INCREASING TO 15 TO 25 MPH WITH GUSTS TO 35 MPH, WITH THE  
STRONGEST WINDS FAVORING THE SE 2/3RDS OF CWA OVERNIGHT INTO  
MUCH OF SATURDAY BEFORE SLOWLY DIMINISHING LATE IN THE DAY INTO  
SATURDAY NIGHT.  
 
MAIN IMPACTS...  
1) PERIODS OF LOW VISIBILITY AND POSSIBLY NEAR WHITEOUT FOR BRIEF  
PERIODS OF TIME IN BLOWING SNOW AND DURING MODERATE TO LOCALLY  
HEAVY SNOWFALL RATES.  
2) EVOLVING DRIER/FLUFFY NATURE OF SNOW WITH THE BRISK/GUSTY WINDS  
MAY LEAD TO CONSIDERABLE DRIFTING OF SNOW HAMPERING REMOVAL EFFORTS.  
3) WIND CHILLS LOWERING INTO THE SINGLE DIGITS ABOVE/BELOW ZERO.  
   
LONG TERM
 
(SATURDAY NIGHT THROUGH THURSDAY)  
ISSUED AT 320 AM CST FRI JAN 18 2019  
 
SATURDAY NIGHT THROUGH SUNDAY NIGHT  
 
COLD WEATHER WILL BE THE MAIN STORY FOR THE SECOND HALF OF THE  
WEEKEND. WE'LL HAVE BELOW NORMAL TEMPS, BUT NOTHING TOO UNUSUAL FOR  
MID JANUARY. FORECAST LOWS ARE IN THE SINGLE DIGITS ABOVE AND  
BELOW ZERO. THE GOOD NEWS IS WINDS WILL BE LIGHT, KEEPING WIND  
CHILLS GENERALLY BETWEEN -10 TO -5 F. WITH THE FRESH SNOW COVER  
AND LOW-LEVEL INVERSION, TEMPS WILL STRUGGLE TO REBOUND INTO THE  
LOW TO MID TEENS SUNDAY AFTERNOON.  
 
THERE IS ALSO A CHANCE FOR A BAND OF LIGHT SNOW TO DRIFT IN FROM  
THE NW ON SUNDAY AS 850MB WARM AIR ADVECTION RAMPS UP, BUT MODELS  
ARE NOT IN VERY GOOD AGREEMENT ON THE PLACEMENT. CHANCES WILL  
LIKELY HAVE TO BE INCREASED IN LATER FORECAST UPDATES. MODEL  
SOUNDINGS HAVE A VERY DEEP DGZ, EXTENDING FROM THE SURFACE TO ~3  
KM. IF THIS OCCURS, SNOW TO LIQUID RATIOS WOULD PROBABLY EXCEED  
25:1 AND IT WOULDN'T TAKE MUCH TO GET A FEW INCHES OF VERY FLUFFY  
SNOW IN A NARROW SWATH. OVERALL, CONFIDENCE IS LOW ON THE  
PLACEMENT -- WE SHOULD HAVE A BETTER IDEA LATER TODAY OR TONIGHT.  
 
MONDAY ON  
 
ACTIVE WINTER WEATHER IS EXPECTED INTO NEXT WEEK. ANOTHER AREA OF  
LOW PRESSURE IS FORECAST TO PASS THROUGH THE UPPER MISSISSIPPI  
VALLEY MONDAY NIGHT AND TUESDAY. LATEST MODEL BLEND SURFACE AND  
850MB TEMPS MODERATE TO ABOVE FREEZING OVER ROUGHLY THE SOUTH  
HALF OF THE CWA, WHICH COULD BRING THE RAIN/SNOW LINE INTO AT  
LEAST THE SOUTHERN FORECAST AREA.  
 
DEPENDING ON THE EVENTUAL TRACK AND STRENGTH OF THIS LOW, ANOTHER  
ROUND OF ACCUMULATING SNOW IS POSSIBLE FOR PARTS OF THE AREA. RIGHT  
NOW THE GFS AND ECMWF FAVOR THE NORTHERN AND WESTERN SECTIONS.  
THE MAIN DIFFERENCE BETWEEN THE TWO MODELS IS THE ECMWF IS A  
LITTLE FURTHER SOUTH WITH THE LOW TRACK AND IS A SLIGHTLY COLDER  
SOLUTION. MAKE SURE TO KEEP UP WITH THE LATEST FORECASTS THROUGH  
THE WEEKEND.  
 
BELOW NORMAL TEMPERATURES ARE EXPECTED FOR THE MIDDLE AND END OF  
NEXT WEEK. THE NEXT CHANCE FOR LIGHT SNOW FROM A WEAK CLIPPER SYSTEM  
IS NEXT THURSDAY. UTTECH  
 

 
   
AVIATION
 
(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)  
ISSUED AT 509 AM CST FRI JAN 18 2019  
 
SATELLITE TRENDS SHOW THE BACK EDGE OF THE MVFR STRATUS HAS SLOWED  
CONSIDERABLY, AND NOW APPEARS UNLIKELY TO REACH THE TERMINALS AHEAD  
OF AN APPROACHING WINTER STORM. THIS STORM WILL SPREAD SNOW AND  
IFR CONDITIONS INTO CID AND DBQ MID TO LATE AFTERNOON, REACHING MLI  
AND BRL EARLY EVENING. WIDESPREAD LIFR CONDITIONS THEN LIKELY  
BY LATE EVENING THROUGH OVERNIGHT WITH ACCUMULATING SNOW AND GUSTY  
NORTHEAST WINDS CAUSING SOME DRIFTING SNOW AND POSSIBLE BLOWING  
SNOW, WHICH MAY CONTRIBUTE TO REDUCTIONS IN VISIBILITY. THE SNOW  
SHOULD TAPER OFF LATE TONIGHT THROUGH MID MORNING SATURDAY, BUT GUSTY  
WINDS WILL LIKELY LEAD TO CONTINUING BLOWING SNOW WITH PERIODIC  
VISIBILITY RESTRICTIONS ON SATURDAY.  
 

 
   
DVN WATCHES/WARNINGS/ADVISORIES
 
 
IA...WINTER STORM WARNING FROM 3 PM THIS AFTERNOON TO NOON CST  
SATURDAY FOR CEDAR-CLINTON-DES MOINES-HENRY IA-IOWA-JACKSON-  
JEFFERSON-JOHNSON-KEOKUK-LEE-LOUISA-MUSCATINE-SCOTT-VAN  
BUREN-WASHINGTON.  
 
WINTER STORM WARNING FROM NOON TODAY TO NOON CST SATURDAY FOR  
BENTON-BUCHANAN-DELAWARE-DUBUQUE-JONES-LINN.  
 
IL...WINTER STORM WARNING FROM 3 PM THIS AFTERNOON TO NOON CST  
SATURDAY FOR CARROLL-JO DAVIESS-ROCK ISLAND-STEPHENSON-  
WHITESIDE.  
 
WINTER STORM WARNING FROM 6 PM THIS EVENING TO 3 PM CST SATURDAY  
FOR BUREAU-HANCOCK-HENDERSON-HENRY IL-MCDONOUGH-MERCER-  
PUTNAM-WARREN.  
 
MO...WINTER STORM WARNING FROM 3 PM THIS AFTERNOON TO NOON CST  
SATURDAY FOR CLARK-SCOTLAND.  
 

 
 

 
 
SYNOPSIS...MCCLURE  
SHORT TERM...MCCLURE  
LONG TERM...UTTECH  
AVIATION...MCCLURE  
 
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