Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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579
FXUS63 KDVN 130910
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
310 AM CST SAT FEB 13 2016

.SYNOPSIS...
ISSUED AT 310 AM CST SAT FEB 13 2016

HIGH PRESSURE RIDGE EXTENDED FROM MN TO NORTHERN MO WITH CLEAR
SKIES OVER THE DVN CWA WITH CURRENT TEMPERATURES MAINLY IN THE
SINGLE DIGITS ABOVE ZERO. WIND CHILLS WERE IN THE 10 TO 20 BELOW
ZERO RANGE ACROSS THE NORTHERN CWA. WARM AIR ADVECTION ON THE
RETURN FLOW WEST OF THE RIDGE MID/HIGH LEVEL CLOUDS HAD SPREAD
INTO WESTERN IA AND WESTERN AND CENTRAL MO.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 310 AM CST SAT FEB 13 2016

HEADLINES...HAVE ISSUED A WINTER WEATHER ADVISORY FOR TONIGHT
THROUGH SUNDAY FOR THE ENTIRE CWA FOR A TOTAL OF 3 TO 5 INCHES OF
SNOW...ALONG WITH WIND GUSTS OVER 25 MPH.

WIND CHILL ADVISORY REMAINS IN EFFECT UNTIL 9 AM THIS MORNING FOR
LOCATIONS ALONG AND NORTH OF HIGHWAY 30. WITH LESSENING WINDS
TOWARDS SUNRISE TEMPERATURES AND WIND CHILLS SHOULD DROP FURTHER.

TODAY...HIGH PRESSURE RIDGE OVER THE CWA THIS MORNING WILL BE
SHIFTING TO THE EAST THIS AFTERNOON. INCREASING WARM AIR ADVECTION
IN THE RETURN FLOW WILL BE SPREADING MID/HIGH LEVEL CLOUDS INTO OUR
SW CWA LATE THIS MORNING...AND OVER THE REMAINDER OF THE CWA EXCEPT
THE FAR EASTERN COUNTIES BY LATE IN THE DAY. TEMPERATURES WILL BE
WELL BELOW NORMAL FOR MID FEBRUARY WITH HIGHS RANGING FROM 11 TO 19.
AT LEAST THE WINDS WILL BE LIGHT WITH THE RIDGE OVERHEAD.

TONIGHT...MODELS FAIRLY SIMILAR IN DEPICTING AN IMPRESSIVE WARM AIR
ADVECTION WING DEVELOPING IN OUR SW CWA THIS EVENING AND SPREADING
NORTHEAST OVER THE REMAINDER OF THE CWA OVERNIGHT...REACHING OUR FAR
EASTERN COUNTIES LATE TONIGHT. MODERATE TO STRONG FORCING WITH
COMPLETE TOP DOWN SATURATION OF THE COLUMN AND A DEEP DENDRITIC
GROWTH ZONE WILL ALLOW FOR A NICE STEADY LIGHT TO MODERATE SNOWFALL.
CERTAINLY CAN`T RULE OUT THE POTENTIAL FOR BRIEF HEAVY SNOWFALL AT
TIMES. USING A MODELED SNOW-LIQUID RATIO OF 16:1 YIELDS ACCUMULATIONS
TONIGHT GENERALLY IN THE 1 TO 2 INCH RANGE WITH ISOLATED SPOTS OF
3 INCHES POSSIBLE. SOUTHEAST WINDS WILL ALSO INCREASING LATE
TONIGHT IN OUR WESTERN CWA WITH GUSTS OVER 20 MPH. MINIMUM TEMPERATURES
SHOULD RANGE FROM THE SINGLE DIGITS NORTH TO THE TEENS SOUTH.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 310 AM CST SAT FEB 13 2016

THE WARM ADVECTION WING OF SNOW WILL BE ONGOING AT THE START OF
THE PERIOD SUNDAY...AND WILL CONTINUE THROUGH THE MORNING IN MOST
LOCATIONS...BEFORE DIMINISHING SOMEWHAT WEST TOWARD NOON AS THE
BAND SHIFTS EAST. THIS SHOULD PROVIDE AROUND 8 HOURS OF GOOD
DENDRITIC SNOWS IN MOST LOCATIONS BEFORE SHIFTING OVER TO A LESS
DENDRITIC SNOW THAT COULD CONTINUE THROUGH THE MID EVENING HOURS.
WITH COLD AIR IN PLACE...AND SLOWLY DECREASING WINDS TOWARD
AFTERNOON...WE MAY STILL SEE SOMEWHAT FLUFFY SNOW RATIOS DESPITE
THE DECREASING DENDRITIC NATURE. BY EVENING THOUGH I EXPECT
SOMEWHAT WIDESPREAD LIGHT NON DENDRITIC SNOW TO BE THE RULE...THUS
POPS ARE RAISED TO LIKELY AND MAY NEED FURTHER UPWARD ADJUSTMENT
FOR COVERAGE...BUT OVER ALL ADDITIONAL AMOUNTS SHOULD BE WELL
UNDER 1 INCH AT THAT POINT. THE 15 TO 18 TO ONE SNOW RATIO
AVERAGES GIVEN MY BLENDED MODEL DATA SUPPORT DAYTIME ACCUMULATIONS
ON THE ORDER OF 3 TO 4 INCHES. EVENT TOTAL ACCUMULATIONS OF 3 TO 5
INCHES APPEAR LIKELY. ALL OF THIS LEADS TO A FAIRLY LONG DURATION
ADVISORY...WITH A COMBINATION OF WIND AND SNOW LEADING TO LIGHT
SNOWS AND LESS WIND. NOT A SITUATION LIKELY TO REPRESENT A WARNING
EVENT AS WINDS ON THE BACK SIDE ARE NOT EXPECTED TO BRING ANY
BLOWING SNOW. THE ADVISORY WILL EXTEND TO 6 PM TO COVER THE LAST
OF THE REMAINING DENDRITIC SNOW POTENTIAL BEFORE A CHANGE TO FINE
LIGHT SNOWS.

AFTER A QUIET LATE NIGHT SUNDAY NIGHT AND MONDAY...ANOTHER CLIPPER
IS EXPECTED TO MOVE THROUGH THE REGION LATE MONDAY NIGHT AND
TUESDAY. THE MODEL BLEND HAS CHANCE POPS FOR THIS SYSTEM...AND THAT
SEEMS HIGH ENOUGH FOR NOW...GIVEN SOME POTENTIAL FOR IT TO MISS OUR
CWA TO THE SOUTHWEST. TEMPERATURES WILL BE NEAR SEASONAL NORMALS
THROUGH TUESDAY BEFORE HIGH PRESSURE BRINGS A COOLER DAY
WEDNESDAY...IN THE 20S. HOWEVER...BEHIND THAT HIGH...A PATTERN SHIFT
TOWARD STRONG SOUTHERLY FLOW AND MUCH MORE MILD AIR REMAINS FORECAST
THROUGH THE END OF THE WEEK. HIGHS MAY INITIALLY STRUGGLE TO EXCEED
40 DUE TO SNOW COVER...BUT THE STRONG SOUTHERLY FLOW AND MIXING WILL
EVENTUALLY DRAW IN DEWPOINTS ABOVE 35...RESULTING IN FAST MELTING
SNOW AND A HIGH LIKELIHOOD OF UPPER 40S TO MID 50S BY FRIDAY.

BEYOND THIS...IN THE 7 TO 10 PERIOD...THE ECMWF AND GFS DIVERGE AS
THE GFS KEEPS MILD AIR IN PLACE...WITH A NEAR SEASONAL CHANGE
FORECAST...WHILE THE ECMWF RETURNS TO A MUCH COLDER EASTERN TROF
ALOFT PATTERN. GIVEN OUR LACK OF COLD AIR THIS WINTER IN
GENERAL...THE GFS PATTERN MAY HOLD SOME SUPPORT.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1120 PM CST FRI FEB 12 2016

AN ARCTIC HIGH OVER THE EASTERN DAKOTAS WILL PROVIDE MOSTLY CLEAR
SKIES AND DECREASING NORTHWEST WINDS AS IT MOVES SOUTHEAST INTO
IOWA OVERNIGHT THROUGH MUCH OF SATURDAY. THIS WILL KEEP CONDITIONS
VFR THROUGHOUT WITH LIGHT NORTH TO NORTHWEST WINDS DURING THE DAY
BECOMING SOUTHEAST AT ALL SITES SATURDAY EVENING. AN APPROACHING
WINTER STORM SYSTEM IS EXPECTED TO BRING DETERIORATING CONDITIONS
BEGINNING LATE SATURDAY NIGHT INTO EARLY SUNDAY MORNING. THE
EARLIEST ONSET MAY AFFECT THE BRL SITE...WHERE PROB30 WORDING FOR
LIGHT SNOW IS INCLUDED WAS USED IN THE SATURDAY EVENING PERIOD.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...WINTER WEATHER ADVISORY FROM 9 PM THIS EVENING TO 6 PM CST
     SUNDAY FOR BENTON-BUCHANAN-CEDAR-CLINTON-DELAWARE-DES
     MOINES-DUBUQUE-HENRY IA-IOWA-JACKSON-JEFFERSON-JOHNSON-
     JONES-KEOKUK-LEE-LINN-LOUISA-MUSCATINE-SCOTT-VAN BUREN-
     WASHINGTON.

     WIND CHILL ADVISORY UNTIL 9 AM CST THIS MORNING FOR BENTON-
     BUCHANAN-CLINTON-DELAWARE-DUBUQUE-JACKSON-JONES-LINN.

IL...WINTER WEATHER ADVISORY FROM 9 PM THIS EVENING TO 6 PM CST
     SUNDAY FOR BUREAU-CARROLL-HANCOCK-HENDERSON-HENRY IL-JO
     DAVIESS-MCDONOUGH-MERCER-PUTNAM-ROCK ISLAND-STEPHENSON-
     WARREN-WHITESIDE.

     WIND CHILL ADVISORY UNTIL 9 AM CST THIS MORNING FOR CARROLL-JO
     DAVIESS-STEPHENSON-WHITESIDE.

MO...WINTER WEATHER ADVISORY FROM 9 PM THIS EVENING TO 6 PM CST
     SUNDAY FOR CLARK-SCOTLAND.

&&

$$

SYNOPSIS...HAASE
SHORT TERM...HAASE
LONG TERM...ERVIN
AVIATION...SHEETS



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