595  
FXUS63 KDVN 201200  
AFDDVN  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE QUAD CITIES IA IL  
600 AM CST WED FEB 20 2019  
   
..AVIATION UPDATE
 
 
   
SYNOPSIS
 
 
ISSUED AT 404 AM CST WED FEB 20 2019  
 
TWO MAIN AREAS OF SNOW WERE SLOWING WORKING FROM SW TO NE THROUGH  
THE FORECAST AREA AS OF 230 AM, ONE ALONG AND NORTH OF HIGHWAY 30  
AND THE OTHER SOUTH OF I-80. THERE WAS A NOTABLE DRY SLOT IN BETWEEN  
THAT ENCOMPASSED THE I-80 CORRIDOR TO THE EAST OF IOWA CITY.  
 
LOW TO MID-LEVEL WARM AIR ADVECTION IS VERY STRONG, ESPECIALLY NEAR  
700MB. ADDITIONALLY, MID-LEVEL FRONTOGENETIC RESPONSE BENEATH THE  
RIGHT ENTRANCE REGION OF AN UPPER JET HAVE LEAD TO MESOSCALE BANDS  
OF MODERATE TO HEAVY SNOW. THE STRONGEST AREA OF FORCING ON THE NOSE  
OF A 700MB JET AND EAST-TO-WEST ZONE OF 700MB FGEN HAS REACHED IOWA  
CITY WITH HEAVY SNOW SHOWN ON RADAR. THIS SHIELD OF SNOW WILL FILL  
IN THE DRY SLOT THAT EXISTS TO THE EAST.  
 
WE HAVEN'T RECEIVED MANY SNOWFALL REPORTS SO FAR. BUT A ROUGH  
ESTIMATION IS BETWEEN 1 TO 4 INCHES WHERE THERE HAS BEEN STEADY  
SNOW. THE HIGHEST AMOUNTS OF 2-3+ ARE LIKELY NORTH OF HIGHWAY 30.  
 
AS OF 230 AM, SURFACE OBSERVATIONS CONTINUE TO SHOW ALL SNOW IN THE  
FAR SOUTHERN CWA WITH LIGHT SNOW AT KEOKUK AND MACOMB. HOWEVER, A  
LITTLE FURTHER SOUTH AT KIRKSVILLE, MO FREEZING RAIN WAS BEING  
REPORTED NEAR THE 0 C MAX WETBULB ALOFT ISOTHERM PER SPC  
MESOANALYSIS.  
 

 
   
SHORT TERM
 
(TODAY AND TONIGHT)  
ISSUED AT 404 AM CST WED FEB 20 2019  
 
WINTER HEADLINES REMAIN IN EFFECT FOR THE CWA. BIGGEST CHANGE WAS TO  
MOVE UP THE END TIME TO 12 PM FOR COUNTIES ALONG AND SOUTH OF I-80.  
THE HEAVIEST SNOW AMOUNTS WILL BE NORTH OF LINE FROM GALENA TO IOWA  
CITY WITH ANYWHERE FROM 3 TO 7 INCHES POSSIBLE. THE HIGHEST AMOUNTS  
OF 5-7" SHOULD BE ALONG AND WEST OF A DUBUQUE TO CEDAR RAPIDS LINE.  
TO THE SOUTH, LOWER TOTALS ARE EXPECTED DUE TO LESS QPF AND A CHANCE  
FOR A WINTRY MIX.  
 
FOR AREAS IN THE WINTER WEATHER ADVISORY, TOTAL SNOWFALL SHOULD  
RANGE BETWEEN 1 AND 4 INCHES WITH ISOLATED HIGHER AMOUNTS NORTH OF  
HIGHWAY 30 AS ALLUDED TO. ANOTHER IMPACT TO TRAVEL IS BLOWING AND  
DRIFTING FROM EAST WINDS GUSTING BETWEEN 20-30 MPH. THE WINDS WILL  
DECREASE FROM SOUTH TO NORTH THROUGH THE MID TO LATE MORNING.  
 
THE MOST LIKELY AREA FOR A PERIOD OF FREEZING RAIN AND FREEZING  
DRIZZLE, WHICH COULD MIX WITH SLEET AT TIMES, IS TO THE SE OF A  
FREEPORT TO IOWA CITY LINE. HERE, THE MAX WETBULB ALOFT WILL WARM TO  
NEAR OR ABOVE 0 C AS THE PRECIPITATION BECOMES LIGHTER THROUGH THE  
MID TO LATE MORNING. ADDITIONALLY, FORECAST SOUNDINGS SHOW DRYING IN  
THE CRITICAL -10 TO -13 C LAYER FOR IN-CLOUD ICE, WHICH COULD RESULT  
IN PRECIPITATION SWITCHING BACK AND FORTH BETWEEN SNOW AND A MIX.  
ICE ACCUMULATIONS AROUND A TENTH ARE POSSIBLE ALONG AND SOUTH OF A  
LINE FROM PRINCETON, IL TO MEMPHIS, MO.  
 
HIGHS WILL REACH THE LOWER TO UPPER 30S FROM NW TO SE THIS AFTERNOON  
WHICH SHOULD REALLY HELP TO IMPROVE ROAD CONDITIONS. AS THE SURFACE  
LOW PULLS NORTH OF IOWA, RESIDUAL SNOW SHOWERS ARE POSSIBLE THROUGH  
THE AFTERNOON. ADDITIONAL ACCUMULATIONS BETWEEN 12 AND 3 PM OF A  
DUSTING TO AN INCH OR SO ARE POSSIBLE NORTH OF HIGHWAY 30. ELSEWHERE  
LITTLE TO NO ACCUMULATION IS EXPECTED. UTTECH  
   
LONG TERM
 
(THURSDAY THROUGH TUESDAY)  
ISSUED AT 404 AM CST WED FEB 20 2019  
 
THURSDAY AND FRIDAY...HIGH PRESSURE GRADUALLY BUILDING INTO THE  
MIDWEST WILL BRING PRECIPITATION FREE WEATHER TO THE AREA. WE  
WILL BE ON THE COLD SIDE OF THE SURFACE RIDGE THURSDAY WITH  
GENERALLY BELOW NORMAL TEMPS, BUT AS THE RIDGE SLIDES EAST FRIDAY  
AND RETURN FLOW DEVELOPS, SOME LOCATIONS ESPECIALLY IN THE SOUTH  
WILL EXPERIENCE ABOVE NORMAL TEMPS.  
 
FRIDAY NIGHT THROUGH SUNDAY...LOOKS TO BE A VERY INTERESTING PERIOD  
AS A SYSTEM NOW OFF THE PACIFIC COAST DIGS WELL SOUTH INTO NORTHWEST  
MEXICO BEFORE SWINGING NORTHWARD INTO THE CENTRAL US. PRECIP IS  
EXPECTED TO BREAK OUT WITH A LEADING WAVE FRIDAY NIGHT, BUT THE  
BIGGER EVENT IS STILL ON TRACK FOR SATURDAY AFTERNOON AND NIGHT.  
 
THE MODELS HAVE TRENDED WARMER THE LAST SEVERAL RUNS SUGGESTING THE  
ICE THREAT MAY BE LIMITED TO NORTH OF US HIGHWAY 34 FRIDAY NIGHT.  
ANY ICE SHOULD THEN CHANGE TO RAIN BY SATURDAY MORNING AS WARMER AIR  
AHEAD OF THE STORM SYSTEM PUSHES INTO THE AREA.  
 
AS THE INTENSE SURFACE LOW RAPIDLY MOVES NORTHEAST ACROSS OUR AREA  
SATURDAY NIGHT, COLDER AIR WILL DROP IN BEHIND THE SYSTEM CHANGING  
THE RAIN TO SNOW LATE SATURDAY EVENING INTO EARLY SUNDAY MORNING. AT  
THIS POINT ACCUMULATIONS DON'T LOOK TO BE SIGNIFICANT.  
 
WHILE MUCH FOCUS WITH THIS STORM HAS BEEN ON THE PRECIP, THE MODEL  
CONSENSUS OF A RAPIDLY DEVELOPING SURFACE LOW WITH GOOD UPPER LEVEL  
SUPPORT SUGGESTS SATURDAY AND SUNDAY WILL BE QUITE WINDY, POSSIBLY  
MEETING WIND ADVISORY CRITERIA WITH GUSTS UP TO AROUND 40 MPH.  
 
MONDAY AND TUESDAY...MODEL CONSENSUS IS LACKING IN THIS TIME  
FRAME BUT THE OVERALL THEME SUGGESTS A RATHER UNSETTLED PERIOD  
WITH ANOTHER STORM FORECAST LATE MONDAY INTO EARLY TUESDAY. IT'S  
STILL TO EARLY TO EVALUATE ANY DETAILS GIVEN THE MODEL  
DISCREPANCIES ARE SO GREAT.  
 

 
   
AVIATION
 
(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)  
ISSUED AT 542 AM CST WED FEB 20 2019  
 
PERIODS OF LIGHT TO MODERATE SNOW AND A WINTRY MIX WILL CONTINUE  
THIS MORNING. IFR/LIFR WILL PREVAIL INTO THE AFTERNOON DUE TO LOW  
CEILINGS. MVFR/IFR VISIBILITIES ARE EXPECTED THROUGH THE MORNING  
BEFORE IMPROVEMENT TO VFR. A LIGHT GLAZING OF ICE FROM LIGHT  
FREEZING RAIN OR FREEZING DRIZZLE IS POSSIBLE AT KBRL AND KMLI  
THROUGH 9-10 AM. THERE COULD ALSO BE A BRIEF PERIOD OF FREEZING  
DRIZZLE AT KCID/KDBQ.  
 
THE BEST CHANCES FOR ADDITIONAL SNOW ACCUMULATIONS ARE AT KCID AND  
KDBQ WHERE 1-3 INCHES ARE POSSIBLE, HIGHER AT KDBQ. GUSTY EAST  
WINDS EARLY THIS MORNING WILL SUBSIDE BY MIDDAY AND THEN VEER TO  
THE WSW LATE THIS AFTERNOON, BECOMING GUSTY AGAIN. UTTECH  
 

 
   
CLIMATE
 
 
ISSUED AT 404 AM CST WED FEB 20 2019  
 
WEEK 2...THE CPC OUTLOOK FOR FEB 27 TO MAR 5 INDICATES A HIGH  
PROBABILITY OF BELOW NORMAL TEMPERATURES ACROSS THE AREA, REFLECTING  
THE LIKELIHOOD ANOTHER ARCTIC OUTBREAK WORKING ACROSS THE MIDWEST.  
HIGH AMPLITUDE FLOW AND BELOW NORMAL HEIGHTS OBSERVED IN MODEL  
ENSEMBLE MEANS SUPPORT THE PATTERN BRINGING COLDER AIR TO MUCH OF  
THE NORTH-CENTRAL U.S.  
 

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

 
 

 
 
SYNOPSIS...UTTECH  
SHORT TERM...UTTECH  
LONG TERM...WOLF  
AVIATION...UTTECH  
CLIMATE...WOLF  
 
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