Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 161239
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
639 AM CST TUE DEC 16 2014

.UPDATE...
ISSUED AT 625 AM CST TUE DEC 16 2014

MAIN UPDATE TO ADJUST POPS FOR DIMINISHING TREND AND ALSO BACK OFF
THE WINTRY MIX. MEASURABLE PCPN ENDING OVER WESTERN CWA WITH BACK
EDGE OF LIGHT RAIN APPROACHING MISS RVR ATTIM MOVING EAST. HAVE
UPDATED POPS TO COVER THE DIMINISHING TREND OF RAIN ALONG/E OF
MISS RVR NEXT COUPLE OF HOURS. OTHERWISE...SOME VERY LIGHT SPOTTY
PCPN STILL POSSIBLE REST OF THIS AM THROUGH MIDDAY BEING WRUNG OUT
BY COLD ADVECTION. WITH ICE INTRODUCTION VARYING PTYPE LIKELY TO BE
EITHER FLURRIES OR SOME DRIZZLE.

&&

.SYNOPSIS...
ISSUED AT 308 AM CST TUE DEC 16 2014

VERTICALLY STACKED CYCLONE PASSED OVERHEAD A LITTLE WHILE AGO WITH
WATER VAPOR IMAGERY SHOWING UPPER LEVEL LOW CENTER PASSING
BETWEEN MUSCATINE IA AND GALESBURG IL... WHILE SFC OBS SHOWED THE
SURFACE LOW CENTER MOVED THROUGH THE QUAD CITIES. STACKED CYCLONE
IS NOW ON THE MOVE EAST AS INTERACTION WITH DIGGING WESTERN
ONTARIO TROUGH IS AIDING IN ACCELERATION OF SYSTEM TOWARD THE GREAT
LAKES. MOST OF THE AREA NOW FINDS ITSELF ON BACKSIDE OF THE
DEPARTING SYSTEM CHARACTERIZED BY STRENGTHENING NORTHWEST WINDS
AND FALLING TEMPS AS COLDER AIR ENVELOPS REGION. RADAR SHOWS SOME
WRAP-AROUND AREAS OF RAIN AND DRIZZLE ACROSS CWA... WHILE
FURTHER WEST A LIGHT WINTRY MIX WAS FOUND IN PORTIONS OF CENTRAL
IA.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 308 AM CST TUE DEC 16 2014

TURNING MUCH COLDER WITH MORE TYPICAL DECEMBER TEMPS AND CHILL.

PCPN LOOKS TO TAPER OFF IN BOTH INTENSITY AND COVERAGE FROM WEST
TO EAST THIS AM... AS STACKED CYCLONE CONTINUES RAPIDLY EXITING
AND MID LEVEL RIDGING BUILDS IN AHEAD OF UPPER LOW DIVING DOWN
ACROSS MN. PCPN LOOKS TO DIMINISH AS STRONGEST COLD ADVECTION
ARRIVES 12Z FAR WESTERN CWA TO 18Z EASTERN CWA. BUFR SOUNDINGS
DEPICT THE LOW LEVEL COLD AIR ADVECTION STRONGEST INITIALLY
WITH RESIDUAL ELEVATED WARM NOSE OF +1 TO +3 C 850-925 MB
LINGERING FOR A TIME... THUS MAY SEE MORE OF RAIN/SLEET MIX THEN
EVENTUALLY FEW FLAKES WITH COMPLETE EROSION OF ELEVATED WARM NOSE
BEFORE PCPN ENDS. THIS TRANSITION WOULD BE OCCURRING AS THE
INTENSITY WANES... AND SO THE BOTTOM LINE IS ANY WINTRY MIX IS
EXPECTED TO BE VERY LIGHT AND NOT LASTING LONG THUS WITH TEMPS
MAINLY AT OR ABOVE FREEZING DURING THIS TIME NO PROBLEMS ARE
EXPECTED. OTHERWISE... MAIN STORY IS THE RETURN OF COLDER AIR ON
BLUSTERY NORTHWEST WINDS OF 15 TO 30 MPH... WITH SOME GUSTS 35 TO
40 MPH AT TIMES WEST OF MISSISSIPPI RIVER THROUGH EARLY PM WITH
BUFR SOUNDINGS SHOWING AROUND 30-35 KTS OF WIND SITTING AT TOP OF
MIXED LAYER. THESE WINDS COMBINED WITH FALLING TEMPS TO MAKE IT FEEL
EVEN COLDER AND MORE LIKE RANGE OF 10-20 DEGS. WITH THE INCREASING
SUBSIDENCE THIS AFTN MAY SEE CLOUDS BREAK UP PORTIONS OF SOUTHERN
AND WESTERN CWA... BUT OVERALL MOCLDY/CLOUDY TDY WITH TEMPS FALLING
THROUGH 30S AND INTO THE 20S WEST.

TONIGHT... MAY SEE CONTINUED BREAKS DEVELOPING IN CLOUDS WITH THE
WRAP-AROUND CLOUDS PERHAPS MORE PERSISTENT NORTH/EAST. ALSO EXPECT
SOME CIRRUS ATTENDANT TO JET STREAK UNDERCUTTING GREAT LAKES LOW.
OVERALL... WHILE SOME AREAS ESPECIALLY WEST AND SOUTH COULD BE
MOCLR FOR A TIME GENERALLY ANTICIPATE PT-MCLDY SKIES. LOWS IN THE
TEENS TO LOWER 20S WITH NORTHWEST WINDS DIMINISHING 5-15 MPH BUT
ENOUGH TO MAKE IT FEEL MORE LIKE THE SINGLE DIGITS TO AROUND 10 DEGS.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 308 AM CST TUE DEC 16 2014

FORECAST FOCUS ON INITIALLY BELOW NORMAL TEMPERATURES THEN TRENDING
TO ABOUT NORMAL AND MAINLY DRY UNTIL ABOUT MONDAY...AND THEN
CHRISTMAS WEEK STARTING TO LOOK WINTRY.

WEDNESDAY...HIGH PRESSURE OVER THE CWA AS UPPER LEVEL TROUGH EXISTS
IN THE EASTERN GREAT LAKES...AND A STORM SYSTEM DEVELOPS IN THE
SOUTHERN PLAINS. TEMPERATURES TO BE ON THE CHILLY SIDE WITH HIGHS IN
THE MID 20S TO LOWER 30S.

THURSDAY...STORM IN THE SOUTHERN STREAM WILL FOR THE MOST PART
REMAIN SOUTH OF THE CWA. HOWEVER...ECMWF/GFS HINT THAT OUR FAR
SOUTHERN CWA MAY BE ON THE NORTHERN FRINGE WITH THE POSSIBILITY OF
FLURRIES. THE ACCUMULATING SNOW SHOULD REMAIN WELL SOUTH OF THE DVN
CWA ACROSS KS AND CENTRAL MO. I WILL KEEP POPS LESS THAN 20 PERCENT.
CHILLY AGAIN WITH HIGHS IN THE UPPER 20S TO LOWER 30S.

FRIDAY THROUGH SUNDAY...THE NEXT STORM SYSTEM IN THE SOUTHERN
STREAM TRACKS EVEN FARTHER SOUTH THAN THURSDAY`S STORM. OPERATIONAL
MODELS ARE NOT PHASING THIS SYSTEM WITH AN UPPER LEVEL TROUGH
DIGGING SOUTHEAST INTO THE MIDWEST. FOR NOW WILL KEEP IT DRY BUT IF
PHASING OCCURRED SOONER THAN INDICATED THERE IS THE CHANCE THE
PRECIPITATION COULD SPREAD FARTHER NORTHWARD CLOSER TO THE DVN CWA.
WE WILL HAVE BETTER TRENDS ON THIS SITUATION OVER THE NEXT COUPLE OF
DAYS.  MAXIMUM TEMPERATURES TREND TO ABOUT NORMAL FOR MID DECEMBER
WITH READINGS IN THE 30S.

CHRISTMAS WEEK...THE AO TAKES A DRAMATIC NOSE DIVE WELL INTO THE
NEGATIVE TERRITORY WHICH OPENS THE GATES TO THE ARCTIC AIR TO DIVE
SOUTHWARD INTO THE COUNTRY. THIS ALLOWS SUDDENLY FOR A MORE ACTIVE
PATTERN INCREASING THE LIKELIHOOD OF SNOWY WEATHER. THE FIRST SUCH
SYSTEM ARRIVES MONDAY INTO TUESDAY TIME FRAME AND I HAVE INTRODUCED
A CHANCE OF SNOW MONDAY NIGHT PER GFS. HOWEVER...THE ECMWF SUGGESTS
RAIN OR A WINTRY MIX TURNING TO SNOW ALREADY ON MONDAY AS A
DEEPENING TROUGH PUSHES INTO THE MIDWEST. MODELS HINT AT AN EVEN
STRONGER SYSTEM AROUND CHRISTMAS (GFS) OR SHORTLY THEREAFTER
(ECMWF). OF COURSE THIS BEING A BIG TRAVEL WEEK YOU WILL NEED TO
STAY TUNED!

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 548 AM CST TUE DEC 16 2014

LIGHT RAIN/DRIZZLE TO GIVE WAY TO SCATTERED FLURRIES BEFORE ENDING
THROUGH EARLY AFTERNOON. NORTHWEST WINDS WILL REMAIN AT OR ABOVE
10 KTS THROUGH THE TAF CYCLE WITH GUSTS 25-32 KTS TDY. OCCASIONAL
GUSTS AROUND 20 KTS MAY LINGER THIS EVENING. LIFR TO IFR CIGS
WILL TRANSITION TO MVFR TDY. THERE MAY BE SOME PARTIAL CLEARING
AND POCKETS OF VFR LATER TDY AND TNGT WITH SUBSIDENCE IN WAKE OF
DEPARTING SYSTEM... BUT MAINTAINED MVFR CIGS FOR NOW.

&&

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

$$

UPDATE...05
SYNOPSIS...05
SHORT TERM...05
LONG TERM...HAASE
AVIATION...05





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