000
FXUS63 KDVN 051412
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
812 AM CST WED MAR 5 2014

.UPDATE...
ISSUED AT 807 AM CST WED MAR 5 2014

JUST ISSUED A WINTER WX ADVISORY FOR COUNTIES ALONG THE I80
CORRIDOR FROM THE IOWA CITY AREA EAST THROUGH PRINCETON IL THROUGH
11 AM. A NARROW BAND OF FGEN FORCED SNOW HAS SET UP OVER THE AREA.
RECENT SHORT TERM MODEL RUNS HOLD THE BAND OVER THE SAME AREA MOST
OF THE MORNING. THERE HAVE BEEN SMALLER INTENSE BANDS EMBEDDED IN
THE AREA OF SNOW THAT HAVE BEEN PRODUCING HEAVY SNOWS FOR SHORT
PERIODS OF TIME. I DON/T SEE ANY REASON WHY THIS WILL NOT CONTINUE
THIS MORNING. EXPECT MOST SNOW AMOUNTS WILL BE IN THE 1 TO 3 INCH
RANGE WITH SOME ISOLATED AMOUNTS AROUND 4 OR MORE INCHES. THE FGEN
WAS OCCURRING IN THE RIGHT ENTRANCE REGION OF AN H3 JET OVER THE
GREAT LAKES. THE JET IS EXPECTED TO WEAKEN LATE THIS MORNING WHICH
SHOULD CAUSE THE SNOW TO DIMINISH.

UPDATE ISSUED AT 608 AM CST WED MAR 5 2014

THE ADVISORY WAS ALLOWED TO EXPIRE FOR DUBUQUE COUNTY AT 6 AM.
SOME ADDITIONAL LIGHT SNOW IS POSSIBLE THE NEXT COUPLE OF HOURS AS
THE BAND OF LIGHT SNOW OVER THE NORTHEAST CORNER OF IA MOVES SOUTH
THROUGH THE AREA...BUT ADDITIONAL SNOWFALL AMOUNTS SHOULD BE UNDER
AN INCH.

THE BAND OF SNOW ALONG I80 CONTINUES TO DEVELOP. SNOWFALL AMOUNTS
WERE UPDATED FOR A BAND TO L TO 2 INCHES FROM ABOUT THE IOWA CITY
AREA THROUGH PRINCETON IL. THIS BAND OF SNOW IS EXPECTED TO SAG
SOUTH BY MID MORNING ENDING THE SIGNIFICANT ACCUMULATIONS. A
SPECIAL WX STATEMENT WAS ALSO RECENTLY ISSUED FOR THIS BAND OF SNOW
CONCERNING RAPIDLY CHANGING ROAD CONDITIONS DURING THE MORNING COMMUTE.

&&

.SYNOPSIS...
ISSUED AT 259 AM CST WED MAR 5 2014

HIGH PRESSURE WAS LOCATED JUST NORTH OF LAKE SUPERIOR EARLY THIS
MORNING WITH A SURFACE LOW OVER NORTHERN TEXAS. A WARM FRONT EXTENDED
NORTHEAST FROM THE LOW THROUGH NORTHERN MO. THE UPPER FLOW REMAINS
NEARLY ZONAL OVER MUCH OF THE U.S. AT 00Z S/WS EMBEDDED IN THE
ZONAL FLOW WERE LOCATED OVER THE NORTHERN PLAINS AND THE SOUTHERN
ROCKIES. THE NORTHERN PLAINS WAVE HAD SPREAD SNOW INTO THE
NORTHERN CWFA EARLY THIS MORNING. TO THE WEST AHEAD OF THE
SOUTHERN ROCKIES WAVE...PATCHY SNOW WAS OCCURRING FROM NEBRASKA
INTO WESTERN IA.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 259 AM CST WED MAR 5 2014

FGEN FORCING AHEAD OF THE NORTHERN PLAINS S/W HAS SET UP THIS MORNING
FROM NORTHEAST IOWA INTO NORTHERN IL. IT APPEARS THE BANDED SNOW
WILL STAY OVER THIS AREA FOR THE NEXT SEVERAL HOURS. SNOWFALL
AMOUNTS WERE INCREASED OVER NW IL TO AROUND 3 INCHES FOR THE MAX.
WITH THE BANDED NATURE OF THE SNOW THE HIGHER AMOUNTS WILL BE HIT
AND MISS SO NOT ALL AREAS IN THE ADVISORY WILL SEE THE HIGHER
AMOUNTS. TO THE WEST WILL CONTINUE TO THE ADVISORY FOR DELAWARE
AND DUBUQUE COUNTIES WHICH ARE ON THE WESTERN EDGE OF THE BETTER
FORCING. THE ADVISORY WILL BE DROPPED SOON FOR BUCHANAN COUNTY
WHERE AMOUNTS WILL LIKELY STAY UNDER AN INCH.

MODELS SAG THE FGEN FORCING SOUTH THIS MORNING AHEAD OF THE
APPROACHING SOUTHERN ROCKIES S/W. THEY COUPLE THE FGEN WITH STEEP
MID LEVEL LAPSE RATES THIS MORNING OVER CENTRAL AND SOUTHERN IA
SUPPORTING A NARROW EAST-WEST BAND OF SNOW DEVELOPING NEAR I80
EARLY THIS MORNING AND PUSHING SOUTH THROUGH THE FORECAST AREA
THROUGH EARLY AFTERNOON. THE AMOUNTS WITH THIS BAND ARE IN
QUESTION AT THIS POINT WITH THE MESO SCALE MODELS SUGGESTING AN
AXIS OF 1 TO 3 INCHES ALONG I80 CORRIDOR. THE HRRR PROGS ARE IN
LINE WITH THE HIGHER QPF RAP13 BUT THE HRRR/S LATEST RUN IS
OVERDOING THE AREA AND INTENSITY OF THE PRECIP OVER CENTRAL AND
SOUTHERN IOWA.  THE NAM/GFS/ECMWF SHOW CONSIDERABLY LESS
QPF/SNOWFALL OVER THE SAME AREA. HAVE KEPT THE FORECAST CLOSER TO
LOW QPF/SNOW AMOUNTS WHICH YIELD A SWATH OF AROUND 1 INCH NEAR I80
FROM THIS MORNING INTO THIS AFTERNOON. THE SNOW SHOULD TAPER OFF
LATE THIS AFTERNOON OR EARLY THIS EVENING WITH LITTLE ADDITIONAL
ACCUMULATION. TEMPERATURES TODAY SHOULD BE IN THE 20S TO LOW 30S.
TONIGHT SOME CLEARING ACROSS THE NORTH AND HIGH PRESSURE NOSING
INTO THE NORTH WILL ALLOW TEMPERATURES TO DROP INTO THE SINGLE
DIGITS WITH TEENS EXPECTED OVER THE SOUTH.

.LONG TERM...(THURSDAY THROUGH TUESDAY) ISSUED AT
259 AM CST WED MAR 5 2014

GRADUAL WARMING TREND TO CONTINUE THROUGH THE EXTENDED FORECAST AS A
PREDOMINANTLY ZONAL AND SOMEWHAT SPLIT UPPER LEVEL FLOW KEEPS ARCTIC
AIR BOTTLED UP WELL TO THE NORTH. A MINOR SETBACK WILL BE SATURDAY
THROUGH SATURDAY NIGHT WHEN A CANADIAN HIGH...FOLLOWING A FRIDAY/S
COLD FRONTAL PASSAGE...IS EXPECTED TO DROP SOUTH INTO THE REGION
KEEPING MUCH OF THE AREA BELOW FREEZING DURING THE DAY AND RETURNING
OVERNIGHT LOWS TO THE SINGLE DIGITS AND TEENS. AT THIS TIME...IT
APPEARS THE BEST CHANCE FOR PRECIPITATION WILL BE FOCUSED ON A
PERIOD OF LIFT BEHIND THIS FRONT FRIDAY NIGHT INTO EARLY
SATURDAY...WHEN LIGHT SNOW WILL BE POSSIBLE.

THURSDAY AND FRIDAY...A DEVELOPING SOUTHERLY RETURN FLOW BETWEEN THE
DEPARTING HIGH OVER SE CANADA AND DEVELOPING FRONT IN THE PLAINS
WILL PRODUCE A WARMING TREND. TEMPERATURES THURSDAY SHOULD WARM AT
LEAST UPPER 30S ACROSS THE SOUTH AND SW...WHILE A SLIGHTLY MORE
SOUTHEASTERLY COMPONENT TO LIGHT WINDS AND POTENTIAL FOR HIGH CLOUD
COVER OVER THE NORTHEAST MAY LIMIT HIGHS TO THE UPPER 20S.
FRIDAY...MODEL CONSENSUS HAS THE COLD FRONT DROPPING THROUGH THE NW
HALF OF THE FORECAST AREA BY EVENING WITH POST FRONTAL
PRECIPITATION. THIS TIMING SHOULD ALLOW THE PREFRONTAL SW
WINDS TO WARM TEMPERATURES INTO THE 30S AND 40S...WITH THE FAR SW
POTENTIALLY TOUCHING 50. THE GFS...WITH ITS HIGH MOISTURE BIAS IN
THE LOW LEVELS...WOULD SUGGEST LOW CLOUDS AND POSSIBLY EVEN DRIZZLE
OR FREEZING DRIZZLE WHICH DOES NOT LOOK REALISTIC. WILL INSTEAD KEEP
THE PRECIPITATION CONFINED TO POST FRONTAL...OVER THE FAR WEST AND
NORTH DURING THE AFTERNOON...THE SPREADING OVER THE ENTIRE AREA
OVERNIGHT. BASED ON FORECAST SOUNDINGS...THIS WOULD BE IN THE FORM
OF RAIN POSSIBLY MIXED WITH SNOW DURING THE DAY...THEN SNOW
OVERNIGHT AS COLDER AIR OVERSPREADS THE AREA UNDER AN AXIS OF
FRONTOGENETICAL FORCING BEHIND THE FRONT THAT DROPS INTO CENTRAL IL
AND SOUTHERN MO. THE AVAILABLE MOISTURE AND MAGNITUDE OF FORCING
LOOK FAVORABLE FOR SOME LIGHT ACCUMULATIONS OF SNOW.

SATURDAY...HIGH PRESSURE ORIGINATING IN WESTERN CANADA DROPS
SOUTHEAST PASSING OVER THE FORECAST AREA SUNDAY MORNING. THERE IS
SOME DISAGREEMENT WITH THIS TIMING...AND FOR NOW...THE MODEL
CONSENSUS REFLECTS A SLOWER PROGRESSION OF THE HIGH AND HOLDS ONTO
LIGHT SNOW OVER THE SOUTH THROUGH AT LEAST SATURDAY MORNING...AS
SHOWN BY THE ECMWF AND GEM. THE COLDER AIRMASS AND SNOW COVER WILL
RETURN HIGHS TO THE 20S TO POSSIBLY LOWER 30S...WITH LOWS AS
MENTIONED POSSIBLY IN THE SINGLE DIGITS.

SUNDAY THROUGH TUESDAY...WHILE THERE REMAINS LOW CONSISTENCY IN THE
TIMING OF SHORTWAVES AND SURFACE FEATURES AMONG MODELS EARLY NEXT
WEEK...A WARMING TREND LOOKS LIKELY FOLLOWING THE DEPARTING HIGH
SUNDAY. CONSENSUS HAS HIGHS IN THE 30S TO LOWER 40S SUNDAY...THEN
REACHING THE 40S TO LOWER 50S...AND POTENTIALLY MUCH WARMER...
TUESDAY. WILL CONTINUE WITH SLIGHTLY COOLER TEMPERATURES TUESDAY AND
SLIGHT CHANCES FOR LIGHT PRECIPITATION BASED ON POOR AGREEMENT WITH
THE TIMING AND PLACEMENT OF THE FRONTAL SYSTEM LIKELY TO AFFECT THE
REGION SOMEWHERE IN THE MONDAY NIGHT THROUGH TUESDAY NIGHT
TIMEFRAME.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 608 AM CST WED MAR 5 2014

SNOW WAS TAPERING OFF OVER NORTHEAST IOWA AND NORTHWEST IL...BUT
REDEVELOPING FURTHER SOUTH ALONG THE I80 CORRIDOR.  FROM THE I80
CORRIDOR SOUTH MVFR CIGS AND VSBYS IN SNOW WITH OCCASIONAL IFR OR
LIFR CANDIDATES WILL SPREAD SOUTH THIS MORNING. THE BAND OF SNOW
RESPONSIBLE FOR THE LOWER CIGS AND VSBYS IS EXPECTED TO WEAKEN AS
IT MOVES INTO SOUTHEAST IOWA AND WEST CENTRAL IL. THE KCID AREA IS
BETWEEN THE TWO AREAS OF SNOW AND SHOULD HAVE VFR CONDITIONS MOST
OF THE MORNING THEN MVFR CIGS AND VSBYS ARE EXPECTED TO DEVELOP
AND REMAIN IN PLACE THROUGH LATE TONIGHT. AFTER THE SNOW ENDS THIS
AFTERNOON...MVFR CIGS AND VSBYS DUE HAZE OR FOG WILL CONTINUE
THROUGH LATE TONIGHT. THERE MAY BE SOME CLEARING FROM THE NORTH
LATE TONIGHT...BUT THE VISIBILITY RESTRICTIONS SHOULD CONTINUE.


&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...WINTER WEATHER ADVISORY UNTIL 11 AM CST THIS MORNING FOR CEDAR-
     JOHNSON-LOUISA-MUSCATINE-SCOTT-WASHINGTON.

IL...WINTER WEATHER ADVISORY UNTIL 11 AM CST THIS MORNING FOR BUREAU-
     HENRY IL-MERCER-PUTNAM-ROCK ISLAND-WHITESIDE.

     WINTER WEATHER ADVISORY UNTIL 9 AM CST THIS MORNING FOR CARROLL-
     JO DAVIESS-STEPHENSON.

MO...NONE.
&&

$$

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