000
FXUS63 KDVN 031128
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
528 AM CST TUE DEC 3 2013

.SYNOPSIS...
ISSUED AT 332 AM CST TUE DEC 3 2013

AS ADVERTISED...MID LEVEL MOISTURE IS RATHER STARVED FOR THIS SYSTEM
AFFECTING THE MIDWEST...BUT LOW LEVEL MOISTURE IS NOW GREATER THAN
ANY MODEL INDICATED OVER 24 HOURS AGO. THIS HAS LED TO WIDESPREAD
LOW CLOUDS AND FOG...SOME OF WHICH IS DENSE IN SOME LOCATIONS IN OUT
SOUTH 1/2. A WARM FRONT REMAINS DRAPED ALONG I-80 IN IOWA...AND
ALONG I-74 IN ILLINOIS.  A SMALL AREA OF SHOWERS...POSSIBLY ELEVATED
IS LOCATED IN EASTERN IOWA...AND IS MOVING EAST AS OF 2 AM. A DENSE
FOG ADVISORY HAS BEEN ISSUED THROUGH 11 AM TODAY FOR OUR CWA AS
DENSE FOG CONTINUES TO EXPAND AS OF 3 AM.
ERVIN

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 332 AM CST TUE DEC 3 2013

MODELS AND OBSERVATIONS NOW SHOW THAT THE WARM FRONT IS MORE LIKELY
TO STALL OVER OUR CWA TODAY...RATHER THAN LIFT NORTH. THIS RESULTS
IN A MORE CLOUDY FORECAST...AND POTENTIALLY A DAY FILLED WITH SOME
DEGREE OF FOG AND DRIZZLE AS WELL. IN ADDITION...TEMPERATURES ARE
NEEDING TO BE LOWERED FROM EARLIER FORECASTS AS THE FRONT WONT MAKES
ITS WAY AS FAR NORTH.  IT WILL STILL BE MILD...WITH MID 40S NORTH TO
LOWER 50S CENTRAL AND UPPER 50S SOUTH. SOME LOW CHANCE FOR
MEASURABLE RAIN EXISTS NORTH OF THE WARM FRONT TODAY...AND A SLIGHT
CHANCE IS RETAINED THERE. HOWEVER...THIS COULD BE MORE OF A
SITUATION WHERE SOME DRIZZLE COMBINES WITH SWEATING CONCRETE FROM
INCREASING DEWPOINTS WILL MAKE IT LOOK WETTER THAN IT REALLY IS.

TONIGHT...WITH THE WARM FRONT LIFTING NORTH AHEAD OF THE MAIN COLD
FROPA WEDNESDAY...WE WILL SEE A FURTHER INCREASE IN LOW LEVEL
MOISTURE. IN FACT...DEWPOINTS ARE LIKELY TO REACH AT LEAST THE MID
40S OVERNIGHT...WITH A POTENTIAL DENSE FOG EVENT NEAR AND AHEAD OF
THE COLD FRONT. AIDING THIS WILL BE A WEAK PRESSURE GRADIENT AHEAD
OF THE COLD FRONT...AND POSSIBLE WAVE ALONG THE FRONT. WE WILL GO
AHEAD AND PLACE BOTH FOG AND DRIZZLE INTO THE FORECAST TONIGHT...AS
MID LEVELS REMAIN DRY THROUGH THE FRONT. TEMPERATURES WILL BE HELD
UP MILD OVERNIGHT...WITH MOST SPOTS REMAINING 40 TO 45 ALL NIGHT
MAINLY DUE TO THE DEWPOINT INCREASE AHEAD OF THE COLD FRONT. FOG AND
DRIZZLE WILL BE THE MAIN STORY TONIGHT...AND WILL HIGHLIGHT THIS IN
THE HWO TODAY.
ERVIN

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 332 AM CST TUE DEC 3 2013

AN ARCTIC FRONT WILL MOVE THROUGH THE AREA ON WEDNESDAY SIGNALING
THE START OF AN EXTENDED PERIOD OF BELOW NORMAL TEMPERATURES. REFER
TO THE CLIMATE SECTION FOR MORE INFORMATION.

A FAIRLY SIGNIFICANT SPREAD CONTINUES WITH THE MODELS REGARDING THE
TIMING OF THE ARCTIC FRONT ON WEDNESDAY. THE CONSISTENT SIGNAL IS A
SLOWING DOWN OF THE ARCTIC FRONT WITH THE GFS/WRF AND TO A LESSER
EXTENT THE ECMWF/GEM. THE GFS/WRF LOOKED TOO FAST BUT NOW THE ECMWF
HAS DONE A SIGNIFICANT SLOW DOWN AS WELL. ONE POSSIBLE REASON FOR
THE SLOW DOWN IS A LOW MOVING NORTH ALONG THE FRONT. IF CORRECT...
THE EASTERN HALF OF THE CWFA WILL AGAIN BE QUITE MILD ON WEDNESDAY
PRIOR TO THE ARRIVAL OF THE FRONT.

AS FOR WEDNESDAY...THE SATURATION IS BELOW 700MB. SO WHILE THERE MAY
BE SOME RAIN...DRIZZLE IS MORE LIKELY TO BE SEEN DURING THE MORNING
HOURS ALONG WITH PROBABLE FOG. THE NEW TIMING OF THE ARCTIC FRONT IS
THE MISSISSIPPI RIVER BY MID DAY WITH IT CLEARING THE AREA BY LATE
AFTERNOON.

TEMPERATURES WILL NOT MOVE MUCH IN THE WESTERN AREAS BUT WILL GET
QUITE MILD PRIOR TO THE FRONT PASSAGE OVER THE EASTERN HALF. COLD
AIR MOVING IN BEHIND THE FRONT WILL CAUSE TEMPERATURES TO DROP
DURING THE AFTERNOON WITH A RAIN/SNOW MIX DEVELOPING OVER THE FAR
NORTHWEST/WEST AREAS BY LATE AFTERNOON.

COLD AIR POURS INTO THE AREA WEDNESDAY NIGHT ON INCREASING WINDS BUT
MAINLY DRY CONDITIONS ARE EXPECTED.

THURSDAY/THURSDAY NIGHT ANOTHER SYSTEM WILL PASS MAINLY SOUTH OF THE
AREA. THE FAR SOUTH MAY GET BRUSHED WITH SOME LIGHT SNOW OR FLURRIES
BUT NO ACCUMULATION IS EXPECTED. TEMPERATURES WILL BE WELL BELOW
NORMAL.

FRIDAY ON...
THE MODEL CONSENSUS HAS SLIGHT CHANCE POPS IN THE FAR SOUTH ON
FRIDAY AS THE SYSTEM FROM THURSDAY/THURSDAY NIGHT SLOWLY EXITS THE
AREA. TEMPERATURES WILL BE EVEN COLDER WITH THE NORTHWEST HALF NOT
LIKELY TO REACH 20 DEGREES ALONG WITH BREEZY CONDITIONS.

FRIDAY NIGHT/SATURDAY THE ARCTIC HIGH MOVES ACROSS THE AREA
RESULTING IN DRY BUT COLD CONDITIONS.

SATURDAY NIGHT THROUGH SUNDAY NIGHT THE MODEL CONSENSUS HAS SLIGHT
CHANCE AND THEN CHANCE POPS. RETURN FLOW BEHIND THE ARCTIC HIGH WILL
BRING MOISTURE INTO THE AREA ALONG WITH AN UPPER LEVEL DISTURBANCE.
THE BOEHMKE RULE WILL BE SATISFIED SO THE PRECIPITATION WILL BE IN
THE FORM OF ALL SNOW. THERE IS A GOOD CHANCE THAT ACCUMULATING SNOW
WILL BE SEEN ACROSS THE AREA. THE RAIN/SNOW RATIO WILL BE QUITE HIGH
BUT AN EARLY GUESS FOR AMOUNTS WOULD BE IN THE 1-2 INCH RANGE.

FOR MONDAY THE MODEL CONSENSUS HAS DRY CONDITIONS AS THE NEXT HIGH
PRESSURE BUILDS INTO THE MIDWEST. TEMPERATURES WILL CONTINUE TO
REMAIN WELL BELOW NORMAL.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 520 AM CST TUE DEC 3 2013

WELL...IT IS PEA SOUP OUT THERE AND YOU PROBABLY SHOULD NOT FLY.
SCIENTIFICALLY...THE LOW LEVEL ADVECTION FOG EVENT IS WIDESPREAD
OVER IOWA AND ILLINOIS THIS MORNING...AND SHOULD LAST THROUGH LATE
MORNING BEFORE BREAKING OUT TO A LOWER END MVFR/HIGH END IFR
STRATUS AND LIGHT FOG. SOUTHEAST WINDS WILL CONTINUE TO PUMP MOIST
AIR OVER THE COLD GROUND...CREATING THIS FOG AND STRATUS. A STRONG
COLD FRONT WILL APPROACH TERMINALS IN EASTERN IOWA AFTER 15Z
WEDNESDAY. THIS MEANS ANOTHER NIGHT OF LOW STRATUS AND DENSE FOG
IS POSSIBLE TONIGHT...ALONG WITH SOME DRIZZLE. MINIMUM CONDITIONS
ARE POSSIBLE OVERNIGHT ONCE AGAIN...BUT FOR NOW...I HAVE GONE WITH
LIFR CIGS AFTER 04Z.
ERVIN

&&

.CLIMATE...
ISSUED AT 332 AM CST TUE DEC 3 2013

.CLIMATE...
ANALYSIS OF THE LONGWAVE PATTERN ACROSS THE NORTHERN HEMISPHERE
INDICATES THAT THE LONGWAVE TROF OVER THE EAST COAST IS IN THE
PROCESS OF BACKING UP INTO THE CENTRAL CONUS. THE GLOBAL MODELS ARE
PROJECTING THIS PATTERN TO REMAIN IN PLACE THROUGH THE FIRST HALF OF
DECEMBER.

A VERY STRONG NEGATIVE TEMPERATURE ANOMALY WILL BE IN PLACE ACROSS
THE NORTHERN PLAINS THROUGH ROUGHLY DECEMBER 10TH OR 11TH. THE
STRENGTH OF THIS NEGATIVE ANOMALY WOULD SUPPORT HIGH TEMPERATURES
AVERAGING 10 TO 15 DEGREES BELOW NORMAL.

AFTER DECEMBER 11TH...THE LONGWAVE TROF OVER THE CENTRAL CONUS
REMAINS IN PLACE BUT THE NEGATIVE ANOMALY OVER THE NORTHERN PLAINS
WEAKENS. TEMPERATURES WILL WARM UP BUT HIGH TEMPERATURES SHOULD
STILL AVERAGE 5 TO 10 DEGREES BELOW NORMAL THROUGH DECEMBER 16TH OR
17TH.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...DENSE FOG ADVISORY UNTIL 11 AM CST THIS MORNING 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.

IL...DENSE FOG ADVISORY UNTIL 11 AM CST THIS MORNING FOR BUREAU-
     CARROLL-HANCOCK-HENDERSON-HENRY IL-JO DAVIESS-MCDONOUGH-
     MERCER-PUTNAM-ROCK ISLAND-STEPHENSON-WARREN-WHITESIDE.

MO...DENSE FOG ADVISORY UNTIL 11 AM CST THIS MORNING FOR CLARK-
     SCOTLAND.

&&

$$

SYNOPSIS...ERVIN
SHORT TERM...ERVIN
LONG TERM...08
AVIATION...ERVIN
CLIMATE...08