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000
FXUS63 KDVN 010548
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1148 PM CST FRI FEB 28 2014

.SYNOPSIS...
ISSUED AT 250 PM CST FRI FEB 28 2014

12Z UPPER AIR ANALYSIS DEPICTED QUASI-ZONAL FLOW ACROSS THE NORTH
CENTRAL PLAINS WITH A STRONG SHORTWAVE TRACKING OVER PARTS OF TEXAS
AND OKLAHOMA. THIS SYSTEM WAS PRODUCING RAIN OVER SOUTHERN MISSOURI
AND ARKANSAS AND EVEN A FEW LIGHTNING STRIKES IN ARKANSAS. LATEST WV
IMAGERY INDICATED ANOTHER SHORTWAVE MOVING OVER THE ROCKIES ATTIM.
THIS WAVE WILL BRING US SOME LIGHT SNOW TO MOST OF THE AREA TONIGHT.
18Z SURFACE ANALYSIS SHOWED A COLD FRONT STRETCHING FROM A SURFACE
LOW ALONG THE MINNESOTA-CANADA BORDER THROUGH SOUTHEAST NEBRASKA.
CLOSER TO HOME...TEMPERATURES HAVE RISEN NICELY ACROSS THE FAR SOUTH
TODAY WHERE MORE SUNSHINE OCCURRED AND LITTLE TO NO SNOW COVER WAS
FOUND. AT 2PM...TEMPS RANGED FROM THE LOWER 20S IN THE FAR NORTH TO
THE LOWER 40S IN NORTHEAST MISSOURI.

&&

.SHORT TERM...(THIS EVENING THROUGH EARLY SATURDAY)
ISSUED AT 250 PM CST FRI FEB 28 2014

FOCUS IS ON THE TIMING OF THE SYSTEM MOVING ACROSS THE PLAINS
TONIGHT BRINGING LIGHT SNOW TO MUCH OF THE AREA.

REST OF TODAY...SOUTH WINDS 10 TO 20 MPH WILL CONTINUE FOR THE NEXT
FEW HOURS BEFORE DECREASING THIS EVENING TOWARDS SUNSET. TEMPS TO
RISE A FEW MORE DEGREES AND TOP OUT IN THE MID 20S NORTH TO THE LOW
40S SOUTH. CLOUD COVER WILL CONTINUE TO INCREASE THROUGH THE EVENING
AS ABOVE MENTIONED SHORTWAVE TRACKS EAST OVER THE PLAINS. MODEL FGEN
PROGS INCREASE BY LATE AFTERNOON/EARLY EVENING ACROSS CENTRAL IOWA
AND THEN MOVES OVER THE CWA MID TO LATE EVENING. THE FAST NATURE OF
THIS SYSTEM WILL ALLOW FOR ROUGHLY A 4 TO 6 HOUR PERIOD OF LIGHT
SNOW AT ANY LOCATION. TAKING THIS INTO ACCOUNT ALONG WITH 12Z MODEL
QPF SOLUTIONS COMING IN SLIGHTLY LOWER GENERALLY LESS THAN A TENTH
OF AN INCH AND SLR/S OF 14 TO 17:1 SUGGEST SNOW AMOUNTS BETWEEN 1
AND 2 INCHES ACROSS NW THIRD OF THE CWA WITH AMOUNTS LESS THAN AN
INCH SOUTH AND EAST OF A LINE FROM OTTUMWA TO IOWA CITY TO
FREEPORT.

TONIGHT...COLD FRONT TO TRACK THROUGH THE CWA SHIFTING WINDS TO THE
NORTHWEST. HAVE RAISED TEMPS SLIGHTLY FROM PREVIOUS FORECAST DUE TO
EXPECTED CLOUD COVER THROUGH MID MORNING. READINGS TO DROP INTO THE
SINGLE DIGITS IN THE NW PORTIONS OF CWA TO THE LOWER 20S IN THE
SOUTHEAST. IF CLOUDS CLEAR OUT FASTER THEN THESE TEMPERATURES MAY BE
TOO OPTIMISTIC. LIGHT SNOW TO TRACK EAST OF THE MISSISSIPPI AFTER
MIDNIGHT WITH FORCING WEAKENING ENDING BY SUNRISE IN THE FAR EASTERN
SECTIONS OF THE CWA.

.LONG TERM...(SATURDAY NIGHT THROUGH NEXT FRIDAY)
ISSUED AT 250 PM CST FRI FEB 28 2014

A VERY CHALLENGING FORECAST IS IN STORE FOR SATURDAY INTO
SUNDAY...AS MODELS ARE AN EXTREME EXAMPLE OF DISCONTINUITY. EVEN AT
THIS LATE STAGE...THERE ARE MODELS FORECASTING EXPLICITLY HEAVY SNOW
AMOUNTS UP THROUGH HIGHWAY 30...WHILE OTHERS PRODUCING LESS THAN 4
INCHES EVEN IN THE FAR SOUTH. THIS IS TROUBLING. IN THIS
INSTANCE...THE ECMWF NOW IS A VERY DRY OUTLIER...AS IS THE
GFS...WHILE THE NAM...UKMET...AND GEM REMAIN QUITE WET...WITH 0.40
TO 0.60 LIQUID OVER MUCH OF THE SOUTHERN 2/3RDS OF THE CWA. RATIOS
LOOK TO BE IN THE 15 TO 17:1 RANGE...AS WIND SHOULD PREVENT ANY 20:1
FROM VERIFYING. WITH SNOW ARRIVING ON FGEN FORCING TOWARD 18Z IN THE
NORTHWEST...AND WITH THAT BAND SLOWLY SINKING SOUTH THROUGH THE
NIGHT...IT SHOULD NOT MODERATELY SNOW IN ANY LOCATION FOR MORE THAN 4
HOURS...WITH LIGHT SNOW POSSIBLE AFTER IT PASSES. THIS SHOULD KEEP
AMOUNTS FROM GETTING TOO HIGH IN OUR CWA. STILL...IT APPEARS THAT
OUR SOUTH COULD SEE LONG ENOUGH FORCING FOR A BROAD 5 TO 7 INCHES
OVER A 18 TO 24 HOUR PERIOD. GIVEN THE LONG DURATION...THIS STILL
SEEMS TO FIT WITH AN ADVISORY VS WARNING. I WILL ALSO GO ADVISORY
FOR AREAS UP THROUGH HIGHWAY 30 AS WELL...GIVEN POTENTIAL FOR 3 TO 4
INCHES DURING THE AFTERNOON AND EVENING HOURS SATURDAY. FOR OUR
SOUTH...I WILL BEGIN THE ADVISORY SATURDAY AT 6 PM...NORTH AT NOON.
IF THIS HAD BEEN A CLOSED LOW SITUATION WITH ALL OTHER VARIABLE THE
SAME...I WOULD HAVE EASILY SEEN A SOLID WARNING EVENT...BUT WITH THE
WAVE SO FAR SOUTH...IT FEEL AN ADVISORY IS A BEST FIT PRODUCT AT
THIS TIME.

BY IN LARGE...MOST LOCATIONS SHOULD BE DONE SNOWING BY 14Z SUNDAY.

WIND CHILLS MAY ACTUALLY REACH ADVISORY LEVELS SATURDAY NIGHT AS
WELL...WITH SOME DRIFTING SNOW AS WELL. ALL IN ALL..IT SHOULD BE A
RATHER WINTRY NIGHT AND SUNDAY MORNING AS WELL.  TEMPERATURES
SATURDAY SHOULD ACTUALLY FALL DURING THE MORNING...BEFORE
STABILIZING SATURDAY AFTERNOON IN THE TEENS TO LOWER 20S. A FALL TO
THE -8 TO ZERO RANGE IS EXPECTED IN THE NORTHWEST 1/2 SATURDAY
NIGHT...WITH TEMPERATURES HOLDING AROUND ZERO FOR HIGHS SUNDAY
NORTHWEST. THIS BITTER COLD WILL LINGER THROUGH AT LEAST MONDAY
NIGHT BEFORE MODERATION OCCURS AS THE HIGH PRESSURE SHIFTS EAST. AS
THAT OCCURS...OUR MODEL BLENDED EXTENDED SHOWS BOTH MILDER HIGHS AND
LOWS...AS WELL AS LOWER POPS FOR CLIPPER SYSTEM SNOWS. BY FRIDAY...A
CHANCE FOR RAIN OR SNOW IS EXPECTED.
ERVIN

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1134 PM CST FRI FEB 28 2014

MVFR WITH POCKETS OF IFR PARAMETERS SNOW EVENT MOVING ON THROUGH
THE TAFS THROUGH 3AM CST THIS MORNING...THEN IMPROVEMENT FROM THE
WEST. THERE MAY STILL BE MVFR CIGS AT DBQ AND POSSIBLY CID THROUGH
5AM CST. NORTH TO NORTHWEST SFC WINDS CONTINUING TO INCREASE TO
10-15KTS THROUGH SAT MORNING. SAT MORNING TO AFTERNOON LULL AND
VFR CONDITIONS...THEN THE NEXT HIGHER BASED FRONTOGENETICAL
FORCING SNOW EVENT TO STREAK INTO THE REGION FROM THE WEST LATE
SAT AFTERNOON AND EVENING. DBQ MAY ACTUALLY BE THE FIRST TO GET
SNOW AND DETERIORATING CONDITIONS AFTER 21Z SAT AFTERNOON. THEN
SOUTHWARD ADJUSTMENT IN THE SNOW BAND TO THE OTHER TAF SITES SAT
EVENING. ROUNDS OF LOW MVFR TO IFR CONDITIONS FROM 01Z-06Z SUNDAY
AS THE SNOW GETS MORE ORGANIZED OVER THE AREA. NORTH WINDS OF
10-15 KTS CONTINUE SAT EVENING FOR SOME DRIFTING SNOW AND HELP
REDUCE VSBYS.   ..12..

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...WINTER WEATHER ADVISORY FROM NOON SATURDAY TO 6 AM CST SUNDAY
     FOR BENTON-CEDAR-CLINTON-IOWA-JACKSON-JOHNSON-JONES-KEOKUK-
     LINN-LOUISA-MUSCATINE-SCOTT-WASHINGTON.

     WINTER WEATHER ADVISORY FROM 6 PM SATURDAY TO NOON CST SUNDAY
     FOR DES MOINES-HENRY IA-JEFFERSON-LEE-VAN BUREN.

IL...WINTER WEATHER ADVISORY FROM NOON SATURDAY TO 6 AM CST SUNDAY
     FOR CARROLL-ROCK ISLAND-WHITESIDE.

     WINTER WEATHER ADVISORY FROM 6 PM SATURDAY TO NOON CST SUNDAY
     FOR BUREAU-HANCOCK-HENDERSON-HENRY IL-MCDONOUGH-MERCER-
     PUTNAM-WARREN.

MO...WINTER WEATHER ADVISORY FROM 6 PM SATURDAY TO NOON CST SUNDAY
     FOR CLARK-SCOTLAND.

&&

$$

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