FXUS63 KDVN 142111
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
305 PM CST MON DEC 14 2009

.SYNOPSIS...
LATEST SFC ANALYSIS WAS INDICATING MAIN SFC LOW ACRS SOUTHERN LOWER
MI AND PROGRESSING EAST-NORTHEASTWARD TOWARD PRESSURE FALLS MAX OVER
LK ERIE. ASSOCIATED ARCTIC FRONT HAS PRETTY MUCH SWEPT THROUGH THE
ENTIRE DVN CWA WITH DEEPENING LLVL NORTHWEST FLOW EVIDENT ALONG
AND WEST OF THE MS RVR. COLD INFLUX ALSO UNDERWAY WITH AMBIENT TEMPS
OF LOWER TEENS AND SINGLE DIGITS PERCHED JUST UPSTREAM ACRS NW IA
INTO THE DAKOTAS.

&&

.SHORT TERM...TONIGHT AND TUESDAY...
ARCTIC COLD DUMP WELL UNDERWAY WITH IMPRESSIVE 1035-140 MB HIGH
PRESSURE LOOMING ACRS SOUTH CENTRAL CANADA AND 1028+ MB LOBING
ALREADY OCCUPYING THE PLAINS. CYCLONIC LOW TO MID LEVEL FLOW WITH
EMBEDDED VORT SPOKES AND STOUT CAA SHOULD STILL WRING OUT A FEW
FLURRIES ACRS AT LEAST THE NORTH HALF OF THE DVN CWA THIS EVENING
EVEN WITH DEEPENING LLVL COLD POOL AND RISING CEILINGS. OTHERWISE
SUBSIDENCE WILL WIN OUT AND SCOUR OUT THE LOWER LEVEL STRATUS AND AC
AFTER MIDNIGHT AND SET THE STAGE FOR ANOTHER FRIGID NIGHT ESPECIALLY
OVER ONGOING SUBSTANTIAL SNOWPACK AREAS. LOOKING AT UPSTREAM AIRMASS
ACRS THE NORTHERN PLAINS...EVEN THE COOLEST OF TEMP GUIDANCE LOOKS
TOO MILD ESPECIALLY OVER THE NORTHWEST HALF OF THE FCST AREA AND WILL
WELL UNDERCUT. EXPECT MANY ZERO TO -5 LOW TEMPS BY 12-14Z TUE MORNING
IN THESE AREAS. RATHER TIGHT PRESSURE GRADIENT ON LEE OF IN-BUILDING
RIDGE AXIS SHOULD KEEP MIXING WINDS GOING OF 8-12 KTS EVEN WITH A
LATE NIGHT CLEAR OUT. ALTHOUGH THIS MIXING WILL PREVENT A COMPLETE
BOTTOM-OUT IN TEMPS...THESE WINDS WILL STILL COMBINE WITH THE AMBIENT
TEMPS TO PRODUCE WIND CHILL ADVISORY CRITERIA OR NEAR ADVISORY WIND
CHILLS OF -17 TO -23 F ROUGHLY ALONG AND NORTH OF I-80 AND WEST OF
THE MS RVR FROM 09Z-17Z TUE. WILL BE ISSUING AN ADVISORY FOR THESE
AREAS AND NIGHT SHIFT WILL HAVE TO ASSESS WHETHER TO EXPAND IT
DEPENDING ON TEMP AND WIND TRENDS LATE TONIGHT.

ON TUE...WITH THE ONGOING LLVL CAA...PLENTY OF INSOLATION STILL
WON/T HELP TEMPS FROM STRUGGLING TO GET OUT OF THE SINGLE DIGITS
ABOVE ZERO OVER SUBSTANTIAL SNOWPACK AREAS. AREAS IN THE FAR SOUTH IN
ERODED SNOW COVER MAY GET TO AROUND 20 DEGREES WITH AREAS IN-
BETWEEN RECOVERING UP INTO THE TEENS. ARCTIC HIGH CENTER MAY BE JUST
SOUTHWEST OF DSM BY 00Z WED.     ..12..

.LONG TERM...TUESDAY NIGHT THROUGH NEXT MONDAY...
FORECAST FOCUS ON DEVELOPING NEGATIVE NORTH AMERICAN OSCILLATION
(NAO) PATTERN DURING THIS PERIOD BRINGING LIGHT SNOWS AND FREQUENT
COLD OUTBREAKS.

CANADIAN HIGH SETTLES OVER THE REGION EARLY IN PERIOD THEN MOVES
INTO THE OHIO VALLEY LATER THIS WEEK. THIS WILL BRING QUIET BUT COLD
WEATHER TUESDAY NIGHT AND WEDNESDAY...FOLLOWED BY SOME MODERATION IN
TEMPS THURSDAY AND FRIDAY.

BLOCKY PATTERN DEVELOPING ACROSS NORTH AMERICA WITH INTENSIFYING
AND RETROGRADING ANOMALOUSLY STRONG BLOCKING RIDGE OVER ICELAND/
GREENLAND. IN THE MEANTIME DEEPENING BROAD UPPER TROUGH/DEEP LOW IN
EASTERN CANADA UNDERCUTTING THE BLOCKING HIGH. IF THAT WASNT ENOUGH
A STRONG STORM SYSTEM APPROACHING THE WEST COAST WILL BE ARRIVING
INTO THE CENTRAL UNITED STATES LATE THIS WEEK. THIS WILL PHASE WITH
THE AMPLIFYING TROUGH TO HELP CARVE OUT A DEEP EASTERN TROUGH BY THE
WEEKEND. A SURE SIGN OF THE -NAO IS A STRONG WAVE THAT DROPS
SOUTHWEST OUT OF EASTERN CANADA AND INTO THE GREAT LAKES/MIDWEST ON
SUNDAY.

WILL CONTINUE WITH CHANCE POPS FOR FRIDAY THROUGH SUNDAY WITH THIS
COMPLEX BUT INTERESTING PATTERN CHANGE. LATER SHIFTS CAN DETERMINE
BETTER RISKS FOR ANY ACCUMULATING SNOWS THAT MIGHT OCCUR. LUCKILY
THE GULF WILL NOT BE A FACTOR THIS FAR NORTH IN THIS PATTERN SO
EXPECTING ONLY LIGHT ACCUMULATIONS. THE SCREAMING MESSAGE IS BELOW
TO WELL BELOW NORMAL TEMPS EXPECTED REMAINDER OF THIS MONTH.

..HAASE..

&&

.AVIATION...
DEEPENING NORTHWEST FLOW BEHIND DEPARTING ARCTIC FRONT TO THE EAST
WILL CONTINUE TO SCOOP CIGS UP INTO THE VFR RANGE THROUGH LATE
AFTERNOON. LINGERING MVFR VSBYS DUE TO FOG AND LIGHT PRECIP SHOULD
ALSO IMPROVE BY 23Z AT ALL TERMINALS. A FEW PASSING FLURRIES MAY ONCE
AGAIN BRING OCCASIONAL BOUTS OF MVFR VSBYS AND CIGS TO MOST TERMINALS
THROUGH 03Z BEFORE SUBSIDENCE AND CLEAR OUT COMMENCES ACRS MOST OF
THE AREA AFTER 06Z.    ..12..

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...WIND CHILL ADVISORY LATE TONIGHT AND TUESDAY MORNING FOR BENTON-
     BUCHANAN- CEDAR-CLINTON-DELAWARE-DUBUQUE-IOWA-JACKSON-JOHNSON-
     JONES- AND LINN.

IL...NONE.
MO...NONE.

&&

$$

12/HAASE