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000
FXUS63 KDVN 101340
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
740 AM CST TUE DEC 10 2013

.UPDATE...
ISSUED AT 740 AM CST TUE DEC 10 2013

MSAS ANALYSIS AT 12Z INDICATED THE FILLING SURFACE LOW MOVING
THROUGH CENTRAL WI WITH TROUGH AXIS TRAILING SW INTO CENTRAL IA.
AXIS OF 3 TO 4 MB PRESSURE RISES OVER SW MN TRENDING SE WILL
SPREAD INTO THE FORECAST AREA LATER THIS MORNING AS THE SURFACE
TROUGH MOVES INTO THE GREAT LAKES...LIKELY PUSHING WINDS INTO A
20 TO 30 MPH RANGE FOR A COUPLE HOUR PERIOD LATER THIS MORNING AS
ADVERTISED.

LATEST RADAR IMAGERY INDICATED AN AREA OF VERY WEAK SNOW SHOWERS
IN THE WARM ADVECTION WING OF THE CLIPPER EXITING INTO N CENTRAL
IL...WHILE A FEW FLURRIES WERE OBSERVED UPSTREAM OVER CENTRAL IA
UNDER THE TROUGH AXIS.

POTENTIAL FOR MEASURABLE SNOW HAS ENDED OVER THE NORTHEAST AND
HAVE ADJUSTED THE FORECAST TO TRIM BACK POPS. FLURRIES OCCURRING
OVER CENTRAL IA WILL SPREAD ACROSS THE CENTRAL AND NORTHERN
FORECAST AREA THIS MORNING. STILL LOOKING AT THE PERIOD OF STRONG
WINDS TO CAUSE BLOWING AND DRIFTING SNOW IN OPEN AREAS FROM LATE
MORNING THROUGH EARLY AFTERNOON.

&&

.SYNOPSIS...
ISSUED AT 340 AM CST TUE DEC 10 2013

UPSTREAM CLIPPER SYSTEM IN NW FLOW ALOFT WAS MOVING INTO WESTERN
MN EARLY THIS MORNING AND WILL TRACK ACROSS WI INTO MI BY MIDDAY.
LIGHT SNOW SHOWERS ASSOCIATED WITH THIS SYSTEM WILL BRUSH THE
NORTHERN THIRD OF THE FORECAST AREA EARLY THIS MORNING. THE SYSTEM
WILL ALSO BRING INCREASING WINDS...CAUSING DRIFTING OF EXISTING
SNOW THIS MORNING INTO EARLY AFTERNOON. ANOTHER CLIPPER WILL QUICKLY FOLLOW
TONIGHT...TRACKING FURTHER SOUTH AND TAKING MORE OF A DIRECT HIT
ON THE FORECAST AREA WITH A QUICK 1 TO 3 INCHES OF SNOWFALL LATE
TONIGHT INTO WEDNESDAY. A BITTER COLD AIRMASS IN PLACE...WITH
SINGLE DIGIT TEMPERATURES EARLY AND WIND CHILLS WELL BELOW ZERO
EARLY THIS MORNING WILL REMAIN IN PLACE THROUGH THURSDAY.

|&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 340 AM CST TUE DEC 10 2013

MAIN FOCUS IS ON THE IMPACTS OF THE TWO CLIPPER SYSTEMS THAT WILL
AFFECT THE REGION IN TODAY AND TONIGHT.

THE SYSTEM THIS MORNING WAS TRENDING A BIT DEEPER AT BOTH 500 MB
AND AT THE SURFACE THAN FORECAST BY THE 00Z MODELS AS OF 06Z. SURFACE
OBSERVATIONS ALSO SHOWED SNOW SHOWERS OCCURRING FURTHER
SOUTH...REACHING INTO FAR NW IA WITH MAINLY FLURRIES SHOWING UP IN
THE WARM ADVECTION WING OVER N CENTRAL IA MOVING INTO NE IA.
FOLLOWING SHORT TERM HIGH RES MODELS THAT APPEAR TO HAVE LATCHED
ONTO THE DEEPER...AND SLIGHTLY MORE SOUTHERLY TRAJECTORY OF THIS
SYSTEM...HAVE INCREASED POPS ACROSS THE NORTH THIS MORNING FOR
SNOW SHOWERS WITH A POSSIBLE DUSTING OF ACCUMULATION BEFORE THE
SYSTEM EXITS MID MORNING. THE ASSOCIATED SURFACE PRESSURE GRADIENT
WILL CONTINUE TO INCREASE SW WINDS WHICH WILL VEER TO THE WEST
WITH SPEEDS OF 15 TO 25 MPH AND GUSTS AS HIGH AS 30 MPH THROUGH
EARLY AFTERNOON. THIS WILL LIKELY CAUSE CONSIDERABLE DRIFTING OF
THE EXISTING SNOW COVER AND ANY ADDITIONAL LIGHT SNOW AND HAVE
KEPT THIS MENTION IN THE FORECAST. INCREASING WINDS THIS MORNING
WILL CONTINUE TO MIX OUT THE LOW LEVEL INVERSIONS THAT CAUSED
SUBZERO EVENING TEMPERATURES...WITH FORECAST DAYTIME HIGHS RANGING
FROM THE TEENS NORTH TO LOWER 20S SOUTH TEMPERATURES STILL ON
TRACK. THE COMBINATION WILL KEEP WIND CHILLS IN THE SINGLE DIGITS
AND TEENS DURING THE MORNING HOURS.

TONIGHT...THE NEXT CLIPPER SYSTEM CURRENTLY WELL TO THE NORTH IN
WESTERN CANADA IS CONSISTENTLY SHOWN TRACKING THROUGH THE FORECAST
AREA WITH A SWATH OF LIGHT SNOW OVER THE CENTRAL AND NORTHERN
PORTIONS. PREVIOUS FORECAST AMOUNTS OF WIDESPREAD 1 TO 3 INCHES
STILL LOOK ON TRACK FOR AREAS ALONG AND NORTH OF I-80 BASED ON THE
TRACK OF THE STRONGEST UPPER FORCING AND QPF EXPECTED ROUGHLY IN A
RANGE OF .10 TO .15. MUCH LIKE THE SUNDAY SYSTEM...THE COLD
TEMPERATURES ALOFT WILL RESULT IN HIGH SNOW TO LIQUID RATIOS APPROACHING
20 TO 1...RESULTING IN A CONFIDENT FORECAST RANGE OF 1 TO 3
INCHES...BUT CANNOT RULE OUT LOCALLY HIGHER AMOUNTS. WITH A WEAK
REFLECTION AT THE SURFACE...WINDS WILL BE RELATIVELY LIGHT DURING
THE SNOWFALL...INCREASING AFTER THE SNOW ENDS TO POSSIBLY PRODUCE
DRIFTING SNOW WED MORNING. CONSIDERING THIS AND THE PRIMARILY
OVERNIGHT PERIOD OF SNOWFALL ACCUMULATIONS...WILL NOT BE ISSUING
AN ADVISORY AT THIS TIME.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 340 AM CST TUE DEC 10 2013

THE FOCUS IN THE EXTENDED PERIOD WAS ON THE SYSTEM FOR FRIDAY
AFTERNOON THROUGH SATURDAY.

COLD AND BLUSTERY WEATHER TO START OUT THE EXTENDED PERIOD...AS
ANOTHER COLD CANADIAN HIGH PLUNGES INTO THE MISSOURI AND MID MS
RIVER VALLEYS WEDNESDAY AND THURSDAY. TEMPERATURES WED WILL BE
FALLING THROUGH THE DAY...AS GUSTY NW WINDS USHER ARCTIC COLD INTO
THE REGION.  HIGHS WILL BE THE DAYBREAK READINGS OF MID SINGLE
DIGITS IN THE NW CWFA...TO NEAR 20 IN THE SOUTH AND EAST.  TEMPS
WILL PLUMMET THROUGH THE DAY...REACHING EVENING COMMUTE READINGS IN
THE SINGLE DIGITS ABOVE AND BELOW ZERO. THIS IS THE COLDEST PERIOD
IN THE EXTENDED.  A WIND CHILL ADVISORY MAY BE NEEDED FOR THE NW 1/3
OF THE AREA FOR MID AM WED THROUGH MID EVENING...AS WIND CHILLS
APPROACH THE -20 TO -25 RANGE.  TEMPERATURES WILL RISE LATE WED INTO
THU AM...AS THE HIGH EXITS AND WINDS DIMINISH AND BACK TO THE
SOUTHWEST.  HIGHS THU WILL REACH THE UPPER TEENS AND 20S.

THE FOCUS THEN TURNS TO THE SYSTEM FOR FRI AND SAT.  A SOUTHERN
PLAINS LOW WILL LIFT NE ACROSS THE LOW-MID MS RIVER VALLEYS...AS A
CANADIAN HIGH PUSHES SOUTH INTO THE UPPER MIDWEST.  PRECIP IS
EXPECTED TO BREAKOUT ACROSS SOUTHERN AND EASTERN AREAS FRI
PM...BEFORE POPS INCREASE FRI EVENING AND OVERNIGHT. THE AREAS WITH
THE BEST CHANCES ATTM ARE SOUTH OF I 80 AS WELL AS AREAS EAST OF THE
MS RIVER. PRECIP TYPE MAY BE AN ISSUE DURING THE ONSET FRI PM...WITH
A SNOW/SLEET/FREEZING RAIN MIX POSSIBLE IN THE SOUTH.  LEFT TYPE AS
ALL SNOW FOR NOW.  LINGERING WRAP AROUND SNOW IS POSSIBLE SUN IN NE
PARTS OF THE CWFA AS THE SYSTEM EXITS...BUT LEFT MENTION OUT OF FCST
ATTM. ARCTIC HIGH BUILDS IN FOR SUN AND MON BRINGING ANOTHER COLD
SHOT.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 340 AM CST TUE DEC 10 2013

MAIN FOCUS IS ON THE IMPACTS OF THE TWO CLIPPER SYSTEMS THAT WILL
AFFECT THE REGION IN TODAY AND TONIGHT.

THE SYSTEM THIS MORNING WAS TRENDING A BIT DEEPER AT BOTH 500 MB
AND AT THE SURFACE THAN FORECAST BY THE 00Z MODELS AS OF 06Z. SURFACE
OBSERVATIONS ALSO SHOWED SNOW SHOWERS OCCURRING FURTHER
SOUTH...REACHING INTO FAR NW IA WITH MAINLY FLURRIES SHOWING UP IN
THE WARM ADVECTION WING OVER N CENTRAL IA MOVING INTO NE IA.
FOLLOWING SHORT TERM HIGH RES MODELS THAT APPEAR TO HAVE LATCHED
ONTO THE DEEPER...AND SLIGHTLY MORE SOUTHERLY TRAJECTORY OF THIS
SYSTEM...HAVE INCREASED POPS ACROSS THE NORTH THIS MORNING FOR
SNOW SHOWERS WITH A POSSIBLE DUSTING OF ACCUMULATION BEFORE THE
SYSTEM EXITS MID MORNING. THE ASSOCIATED SURFACE PRESSURE GRADIENT
WILL CONTINUE TO INCREASE SW WINDS WHICH WILL VEER TO THE WEST
WITH SPEEDS OF 15 TO 25 MPH AND GUSTS AS HIGH AS 30 MPH THROUGH
EARLY AFTERNOON. THIS WILL LIKELY CAUSE CONSIDERABLE DRIFTING OF
THE EXISTING SNOW COVER AND ANY ADDITIONAL LIGHT SNOW AND HAVE
KEPT THIS MENTION IN THE FORECAST. INCREASING WINDS THIS MORNING
WILL CONTINUE TO MIX OUT THE LOW LEVEL INVERSIONS THAT CAUSED
SUBZERO EVENING TEMPERATURES...WITH FORECAST DAYTIME HIGHS RANGING
FROM THE TEENS NORTH TO LOWER 20S SOUTH TEMPERATURES STILL ON
TRACK. THE COMBINATION WILL KEEP WIND CHILLS IN THE SINGLE DIGITS
AND TEENS DURING THE MORNING HOURS.

TONIGHT...THE NEXT CLIPPER SYSTEM CURRENTLY WELL TO THE NORTH IN
WESTERN CANADA IS CONSISTENTLY SHOWN TRACKING THROUGH THE FORECAST
AREA WITH A SWATH OF LIGHT SNOW OVER THE CENTRAL AND NORTHERN
PORTIONS. PREVIOUS FORECAST AMOUNTS OF WIDESPREAD 1 TO 3 INCHES
STILL LOOK ON TRACK FOR AREAS ALONG AND NORTH OF I-80 BASED ON THE
TRACK OF THE STRONGEST UPPER FORCING AND QPF EXPECTED ROUGHLY IN A
RANGE OF .10 TO .15. MUCH LIKE THE SUNDAY SYSTEM...THE COLD
TEMPERATURES ALOFT WILL RESULT IN HIGH SNOW TO LIQUID RATIOS APPROACHING
20 TO 1...RESULTING IN A CONFIDENT FORECAST RANGE OF 1 TO 3
INCHES...BUT CANNOT RULE OUT LOCALLY HIGHER AMOUNTS. WITH A WEAK
REFLECTION AT THE SURFACE...WINDS WILL BE RELATIVELY LIGHT DURING
THE SNOWFALL...INCREASING AFTER THE SNOW ENDS TO POSSIBLY PRODUCE
DRIFTING SNOW WED MORNING. CONSIDERING THIS AND THE PRIMARILY
OVERNIGHT PERIOD OF SNOWFALL ACCUMULATIONS...WILL NOT BE ISSUING
AN ADVISORY AT THIS TIME.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 340 AM CST TUE DEC 10 2013

THE FOCUS IN THE EXTENDED PERIOD WAS ON THE SYSTEM FOR FRIDAY
AFTERNOON THROUGH SATURDAY.

COLD AND BLUSTERY WEATHER TO START OUT THE EXTENDED PERIOD...AS
ANOTHER COLD CANADIAN HIGH PLUNGES INTO THE MISSOURI AND MID MS
RIVER VALLEYS WEDNESDAY AND THURSDAY. TEMPERATURES WED WILL BE
FALLING THROUGH THE DAY...AS GUSTY NW WINDS USHER ARCTIC COLD INTO
THE REGION.  HIGHS WILL BE THE DAYBREAK READINGS OF MID SINGLE
DIGITS IN THE NW CWFA...TO NEAR 20 IN THE SOUTH AND EAST.  TEMPS
WILL PLUMMET THROUGH THE DAY...REACHING EVENING COMMUTE READINGS IN
THE SINGLE DIGITS ABOVE AND BELOW ZERO. THIS IS THE COLDEST PERIOD
IN THE EXTENDED.  A WIND CHILL ADVISORY MAY BE NEEDED FOR THE NW 1/3
OF THE AREA FOR MID AM WED THROUGH MID EVENING...AS WIND CHILLS
APPROACH THE -20 TO -25 RANGE.  TEMPERATURES WILL RISE LATE WED INTO
THU AM...AS THE HIGH EXITS AND WINDS DIMINISH AND BACK TO THE
SOUTHWEST.  HIGHS THU WILL REACH THE UPPER TEENS AND 20S.

THE FOCUS THEN TURNS TO THE SYSTEM FOR FRI AND SAT.  A SOUTHERN
PLAINS LOW WILL LIFT NE ACROSS THE LOW-MID MS RIVER VALLEYS...AS A
CANADIAN HIGH PUSHES SOUTH INTO THE UPPER MIDWEST.  PRECIP IS
EXPECTED TO BREAKOUT ACROSS SOUTHERN AND EASTERN AREAS FRI
PM...BEFORE POPS INCREASE FRI EVENING AND OVERNIGHT. THE AREAS WITH
THE BEST CHANCES ATTM ARE SOUTH OF I 80 AS WELL AS AREAS EAST OF THE
MS RIVER. PRECIP TYPE MAY BE AN ISSUE DURING THE ONSET FRI PM...WITH
A SNOW/SLEET/FREEZING RAIN MIX POSSIBLE IN THE SOUTH.  LEFT TYPE AS
ALL SNOW FOR NOW.  LINGERING WRAP AROUND SNOW IS POSSIBLE SUN IN NE
PARTS OF THE CWFA AS THE SYSTEM EXITS...BUT LEFT MENTION OUT OF FCST
ATTM. ARCTIC HIGH BUILDS IN FOR SUN AND MON BRINGING ANOTHER COLD
SHOT.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 533 AM CST TUE DEC 10 2013

A FAST MOVING LOW PRESSURE SYSTEM MOVING ACROSS MN AND WI WILL
PRODUCE FLURRIES AND PERIODIC MVFR CONDITIONS AT CID AND DBQ EARLY
THIS MORNING AND BRISK WINDS AT ALL TAF SITES THROUGH EARLY AFTERNOON.
OTHERWISE TODAY WILL HAVE VFR CONDITIONS. THERE IS A POSSIBILITY
THAT WINDS MAY RESULT IN BLOWING AND DRIFTING SNOW ON THE GROUND
THAT MAY BE ENOUGH FOR PERIODS OF SURFACE VISIBILITY RESTRICTIONS
AT DBQ AND CID. TONIGHT...ANOTHER FAST MOVING SYSTEM WILL SPREAD
SNOW OVER THE REGION. THE GREATEST IMPACT WILL AGAIN BE AT THE CID
AND DBQ TERMINALS WHERE CONDITIONS ARE TRENDED DOWN TO MVFR AFTER
MIDNIGHT IN THE LATEST FORECASTS. THERE IS A POTENTIAL FOR
VISIBILITIES LOWERING INTO IFR...WHICH MAY BE ADDED IN LATER
FORECASTS.


&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&

$$

UPDATE...SHEETS
SYNOPSIS...SHEETS
SHORT TERM...SHEETS
LONG TERM...14
AVIATION...SHEETS