Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 261250
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
650 AM CST WED NOV 26 2014

.UPDATE...
ISSUED AT 615 AM CST WED NOV 26 2014

BASED ON LATEST HIGH RESOLUTION MODELS...WITH SUPPORT FROM RADAR
TRENDS OF THE SNOW BAND IN CENTRAL IOWA...HAVE MADE SOME ADJUSTMENT
TO THE AXIS OF HIGHER SNOWFALL AMOUNTS. A SLIGHTLY MORE TILTED NW
TO SE AXIS IS NOW EXPECTED...WITH SLIGHTLY LESS SNOW NEAR INDEPENDENCE
AND VINTON...SLIGHTLY HIGHER AMOUNTS ACROSS THE SOUTH. THE HIGHER
TOTALS...AROUND 3 INCHES...NOW EXPECTED FROM WILLIAMSBURG TO
FAIRFIELD...AND SOUTHEAST TO MT. PLEASANT...FORT MADISON AND
BURLINGTON. CANNOT RULE OUT AN ISOLATED 4 INCH AMOUNT IN THE
HEAVIER BAND...BUT NOT ENOUGH CONFIDENCE TO GO AHEAD AND ISSUE A
WINTER WEATHER ADVISORY AT THIS TIME. ANOTHER FACTOR NOT FAVORING
AN ADVISORY IS THE LACK OF STRONG WINDS AND BLOWING/DRIFTING SNOW.

&&

.SYNOPSIS...
ISSUED AT 326 AM CST WED NOV 26 2014

AT 3 AM CST...SURFACE LOW PRESSURE WAS LOCATED NEAR THE IOWA-
NEBRASKA BORDER. AN AREA OF SNOW EXTENDED ACROSS MOST OF WESTERN
AND CENTRAL IOWA. AN EAST TO SOUTHEAST WIND GENERALLY UNDER 10 MPH
CONTINUED AHEAD OF THE CLIPPER SYSTEM ACROSS EASTERN IOWA AND
NORTHWEST ILLINOIS. OVERNIGHT TEMPERATURES DIPPED INTO THE SINGLE
DIGITS FROM CLINTON TO STERLING AND FREEPORT...CO-LOCATED WITH
THE MORE SUBSTANTIAL SNOW COVER AND LIGHTER WIND. ELSEWHERE ACROSS
THE AREA...EARLY MORNING TEMPERATURES WERE IN THE TEENS TO MID
20S.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 326 AM CST WED NOV 26 2014

THE MAIN SHORT TERM FORECAST ISSUE IS SNOWFALL AMOUNTS AND
COVERAGE THROUGH THIS EVENING.

IN THE NEAR TERM...DRIER AIR IN THE LOW LEVELS WILL CONTINUE TO
INHIBIT THE DEVELOPMENT OF SNOW IN THE WESTERN FRINGE OF THE
FORECAST AREA. EXPECTING THE LOWER LEVELS TO SATURATE IN THE FAR
WEST NEAR OR SHORTLY AFTER 12Z.

THE TRACK OF THE CLIPPER THROUGH SOUTHERN IOWA AND NORTHEAST MISSOURI
WILL RESULT IN DRIER NORTHEAST FLOW ACROSS THE NORTHEAST PORTION
OF THE FORECAST AREA AND VERY LIGHT ACCUMULATIONS THERE. MORE
FAVORABLE MOISTURE WILL BE LOCATED OVER THE SOUTHWEST HALF OF THE
FORECAST AREA. BUFKIT SNOW DIAGNOSTICS INDICATE THE SOUTHWEST WILL
SEE THE STRONGEST FORCING IN THE DENDRITIC GROWTH ZONE.
HOWEVER...THERMAL PROFILES QUICKLY WARM TO NEAR OR SLIGHTLY ABOVE
FREEZING AT THE SURFACE...SO SOME MODIFICATION OF THE DENDRITES
IS EXPECTED AS THEY DESCEND THROUGH THE BOUNDARY LAYER. BOTTOM
LINE...NOT ANTICIPATING THE SNOW-TO-LIQUID RATIOS TO GET OUT OF
HAND...AND THE FORECAST SNOWFALL AMOUNTS ARE SIMILAR TO THE
PREVIOUS FORECAST. THE MAIN CHANGE WAS TO INCREASE AMOUNTS A BIT
ACROSS THE SOUTH. DAY SHIFT WILL BE ADVISED TO MONITOR AREAS FROM
FAIRFIELD...TO BURLINGTON AND MACOMB FOR POTENTIALLY HIGHER
AMOUNTS. EXPECTING 1-3 INCH AMOUNTS WEST OF A LINE FROM
MANCHESTER...TO MUSCATINE AND GALESBURG...LESS THAN AN INCH EAST OF
THAT LINE.

AFTER A COUPLE OF PREVIOUS SNOW EVENTS...AND WITH THE LACK OF
COMPLICATING FACTORS SUCH AS STRONG WINDS...WILL NOT ISSUE AN
ADVISORY EARLY THIS MORNING. SNOWFALL TRENDS THROUGH THE DAY CAN
BE HANDLED WITH SPECIAL WEATHER STATEMENTS...ASSUMING SNOWFALL
AMOUNTS AREN`T HIGHER THAN CURRENTLY EXPECTED.

THE SNOW IS EXPECTED TO TAPER OFF THIS EVENING AND OVERNIGHT IN
THE FAR NORTHEAST. COLD AIR ADVECTION BEHIND THE CLIPPER TONIGHT
WILL DROP LOWS INTO THE SINGLE DIGITS NORTHWEST TO UPPER TEENS
SOUTHEAST.   RP KINNEY

.LONG TERM...(THURSDAY THROUGH NEXT TUESDAY)
ISSUED AT 326 AM CST WED NOV 26 2014

THURSDAY AND FRIDAY...ONGOING LLVL COLD POOL...SNOW COVER AND RIDGE
AXIS SLIDING TO THE MS RVR TO MAKE FOR A COLD TURKEY DAY EVEN WITH
SOME INSOLATION...HIGHS ONLY IN THE TEEN TO LOWER 20S. RIDGE-RIDING
WAVE AND UPSTREAM UPPER HIGH BULGE FLATTENING PROCESS WILL LOOK TO
SPILL AN OVERRUNNING ISENTROPIC LIFT PRECIP EVENT ACRS THE UPPER
MIDWEST LATER THU NIGHT INTO FRI. BULK OF THE 00Z RUN MODEL
SOLUTIONS FLUX THIS PRECIP SWATH ALONG AN MAINLY NORTH OF THE DVN
CWA LATE THU NIGHT INTO FRI MORNING...WITH THE 00Z GFS SWITCHING
PLACES WITH THE OLDER ECMWF RUNS OF SATURATING AND LIFTING FURTHER
SOUTH FOR LIGHT SNOW IN THE NORTHEASTERN THIRD OF THE FCST AREA FRI
MORNING. WITH EVEN THE FURTHER NORTH ECMWF STILL JUST BARELY NORTH
OF THE CWA WITH SOME LIGHT SNOW FRI AM...WILL KEEP SLIGHT CHC/S
GOING FROM MANCHESTER IA TO SOUTH OF FREEPORT IN NW IL. WITH
INCREASING RETURN FLOW AND WARMING ON FRI...SOUNDINGS TRANSITION TO
FREEZING RAIN OR DRIZZLE ALONG AND NORTH OF I80 BY MIDDAY OR EARLY
AFTERNOON...BUT WILL BANK THAT ANY LINGERING PRECIP DRIVING
PROCESSES WILL BE NORTHEAST OF THE CWA BY THEN. LATE FRI AFTERNOON
HIGHS RECOVER TO THE UPPER 30S TO MID 40S SOUTH OF I80. INCREASING
TAP INTO BUILDING PLAINS THERMAL RIDGE BY DEEPENING SOUTHWESTERLIES
TO MAKE FOR A STEADY TO SLOW TEMP RISE PHENOMENA LATE FRI NIGHT INTO
EARLY SAT MORNING AFTER AN EVENING DROP-OFF. WILL BANK ON ENOUGH
MIXING SOUTHERLY BREEZE TO PREVENT WIDESPREAD FOG DEVELOPMENT FRI
NIGHT FOR NOW.

SATURDAY AND SUNDAY...STRONG WARM SIGNAL FOR SAT AHEAD OF ORGANIZING
PLAINS FRONTAL SYSTEM EMBEDDED IN FRESHLY ESTABLISHED ZONAL FLOW
REGIME ACRS MUCH OF THE CONUS. EXTENT OF THERMAL DRAW BY EVEN THE
MOST CONSERVATIVE MODEL AND TAKING INTO ACCOUNT SOME POSSIBLE WAA
TYPE CLOUDS AND COOL GROUND...WOULD STILL SUPPORT WIDESPREAD HIGHS
IN THE UPPER 40S IN THE FAR NORTH...MID 50S ALONG I80 AND NEAR 60 IN
THE FAR SOUTH. FOR NOW WILL TREND UP CURRENT ADVERTISED TEMPS BUT
NEAR TO WHAT THE POTENTIAL MAY BE. INCOMING FROPA HAS BEEN SLOWED BY
MOST OF THE 00Z MEDIUM RANGE SOLUTIONS NOT UNTIL SUNDAY...THUS SAT
NIGHT MAY CONTINUE TO BE A WARM SECTOR NIGHT WITH LOWS ONLY IN THE
MID TO UPPER 30S. AGAIN WILL TREND UP THE CURRENT LOW TEMPS BUT NOT
TO WHAT THE POTENTIAL IS JUST YET. WILL KEEP SAT NIGHT DRY ALTHOUGH
PRE-FRONTAL CONVERGENCE WILL BE APPROACHING FROM THE WEST...WILL
BANK ON NOT ENOUGH MOISTURE DEPTH INCREASE TO THE APPROPRIATE LEVELS
TO FUEL PRECIP DEVELOPMENT THRU 12Z SUNDAY. WILL ALSO KEEP SUNDAY
DRY FOR NOW ALTHOUGH THAT MAY BE THE WINDOW FOR AT LEAST SOME LIGHT
PRECIP GETTING WRUNG OUT ALONG THE FROPA. STILL MILD WITH HIGHS IN
THE MORNING TO MIDDAY...BEFORE A LATE AFTER POST FRONTAL COOL OFF
IN INCREASING NORTHWEST WINDS. THE LATEST 00Z MEDIUM RANGE RUNS THEN
IN GOOD AGREEMENT OF SUGGESTING A STRONG 1040+ MB SFC HIGH TO PUMMEL
IT/S WA DOWN ACRS THE PLAINS AND UPPER MS RVR VALLEY SUNDAY NIGHT
INTO MONDAY FRO DRY BUT COOLING CONDITIONS. LOWS IN THE TEENS TO LOW
20S AGAIN BY MONDAY MORNING.

NEXT MONDAY AND TUESDAY...PASSING LARGE ANTICYCLONE ACRS THE WESTERN
GRT LKS TO PROVIDE DRY BUT COLDER CONDITIONS ON MONDAY WITH A SWITCH
BACK TO BELOW NORMAL TEMP REGIME...HIGHS IN THE 20S TO LOW 30S. LONG
RANGE SIGNALS DIVERGE INTO NEXT WEEK...BUT GENERAL IDEA IS FOR
PASSING HIGH COMPLEX AND DIGGING L/W TROF ENERGY ACRS THE ROCKIES TO
INDUCE A LARGE SCALE RETURN FLOW REGIME UP ACRS THE REGION NEXT TUE
INTO WED. WHETHER A WARM MOIST CONVEYOR STRENGTHENS AND RESULTANT
OVERRUNNING PRECIP SCENARIO OCCURS BY LATE TUE IS A CHALLENGE AND AN
UNCERTAINTY...BUT IF IT DOES AND CAN OCCUR EARLY ENOUGH THERE MAY BE
A FREEZING RAIN WINDOW SOMETIME THAT DAY. BUT MANY DETAILS TO BE
HAMMERED OUT BETWEEN NOW AND THEN AND WILL MAINTAIN A DRY FCST INTO
TUE FOR NOW.     ..12..

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 615 AM CST WED NOV 26 2014

EXPECTING MVFR CEILINGS AND VISIBILITIES IN -SN AFTER 15Z AT
KCID/KBRL. CEILINGS WILL DROP DURING THE AFTERNOON/EARLY EVENING
AS LIGHT SNOW SPREADS INTO KMLI/KDBQ BETWEEN 19Z-21Z. HIGHER
INTENSITY SNOW EXPECTED AT KCID/KBRL THIS AFTERNOON WITH PERIODS
OF IFR CONDITIONS. EXPECT MAINLY IFR CEILINGS THIS EVENING WITH LIGHT
SNOW TAPERING OFF BY LATE EVENING.

&&

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

$$

UPDATE...RP KINNEY
SYNOPSIS...RP KINNEY
SHORT TERM...RP KINNEY
LONG TERM...12
AVIATION...RP KINNEY





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