Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 251749
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1149 AM CST TUE NOV 25 2014

.UPDATE...
ISSUED AT 633 AM CST TUE NOV 25 2014

UPDATE TO ADD SOME ISOLATED FLURRIES ALONG AND NORTH OF INTERSTATE
80 UNTIL MID MORNING.

&&

.SYNOPSIS...
ISSUED AT 300 AM CST TUE NOV 25 2014

AT 3 AM CST...A NORTHWEST WIND WAS GUSTING OVER 20 MPH AT MANY
LOCATIONS IN EASTERN IOWA AND WESTERN ILLINOIS. LOW CLOUDS
REMAINED IN PLACE ACROSS THE AREA. AN AREA OF LIGHT SNOW HAD
PUSHED INTO NORTHEAST ILLINOIS. EARLY MORNING TEMPERATURES RANGED
FROM THE MID TEENS TO MID 20S.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 300 AM CST TUE NOV 25 2014

THE MAIN FORECAST ISSUE IN THE SHORT TERM PERIOD IS THE ARRIVAL OF
A CLIPPER SYSTEM LATE TONIGHT.

IN THE NEAR TERM...THE MAIN AREA OF LIGHT SNOW HAS PUSHED EAST OF
THE FORECAST AREA. A FEW FLURRIES ARE EXPECTED TO CLIP THE FAR
NORTHEAST PORTION OF THE FORECAST AREA BASED ON OBS AND UPSTREAM
RADAR TRENDS. OTHERWISE...CLOUDS WILL CLEAR FROM WEST TO EAST
TODAY AS SURFACE HIGH PRESSURE BUILDS IN. AFTERNOON HIGHS ARE
FORECAST IN THE MID 20S NORTHEAST TO LOWER 30S SOUTH.

FOR TONIGHT...EXPECT A QUICK EVENING DROP IN TEMPS WITH AN EXITING
SURFACE RIDGE AND LIGHT SOUTHEAST WINDS. MADE SOME ADDITIONAL
DOWNWARD ADJUSTMENTS TO THE CONSENSUS MODEL TEMP GUIDANCE...ESPECIALLY
ACROSS THE NORTHEAST WHICH RECEIVED 2-3 INCHES OF SNOW MONDAY. THE
AFOREMENTIONED CLIPPER WILL MOVE INTO IOWA OVERNIGHT. MODEL
AGREEMENT ON THE TRACK AND TIMING IS QUITE GOOD...AND SUPPORTS
LIGHT SNOW SPREADING INTO THE FAR WESTERN FRINGE OF THE FORECAST
AREA PRIOR TO DAYBREAK WEDNESDAY. AREAS FROM INDEPENDENCE TO
WILLIAMSBURG AND FAIRFIELD COULD PICK UP A LIGHT DUSTING BEFORE
12Z.   RP KINNEY

.LONG TERM...(WEDNESDAY THROUGH NEXT MONDAY)
ISSUED AT 300 AM CST TUE NOV 25 2014

WEDNESDAY THROUGH FRIDAY...MAIN CHALLENGE THIS PERIOD CONTINUES
TO BE PRE-THANKSGIVING DAY CLIPPER ON WED. ASSESSING THE VARIOUS
00Z MODEL RUNS...SURPRISINGLY SOME GOOD AGREEMENT IN HANDLING
SPEED/PLACEMENT OF THE MAIN LLVL LOW. SEEMS A TREND BY OTHERS TO
THE MORE CONSISTENT ECMWF. WEST CENTRAL IA LOW CENTER WILL LOOK TO
TRAVERSE ACRS INTO NORTHEASTERN MO SOUTH OF KIRKSVILLE BY AROUND
18Z WED...THEN PROGRESSING ACRS SOUTH CENTRAL IL INTO SOUTHEASTERN
IL BY WED EVENING. TAKING THIS PATH INTO ACCOUNT AND A NOD TO THE
ECMWF...MORE ENHANCED FORCING WING IN SATURATION ZONE ON EAST-
NORTHEAST FLANK OF PROPAGATING WAVE WOULD FAVOR A HIGHER STRIP OF
PRECIP ACRS GENERALLY THE SOUTHWESTERN HALF OF THE DVN CWA...A
MORE DEFINED RIBBON FROM NEAR VINTON IA...TO SOUTH OF IOWA CITY
NEAR WASHINGTON...AND TO BRL IA AND DOWN INTO THE CARTHAGE IL AREA
WITH BULK OF BEST LIFT FROM 12Z TO 16Z OR SO WED MORNING. A
LINGERING ELEVATED CONVERGENT TROF EXTENDING OFF TO THE
NORTH/NORTHWEST OF THE PASSING LOW COULD KEEP LIGHTER SNOWS GOING
INTO THE AFTERNOON ACRS MUCH OF THE CWA WITH ADDITIONAL LIGHTER
ACCUMS THROUGH WED EVENING. THERMAL PROFILES SUGGEST MAINLY SNOW
ALMOST CWA-WIDE...WITH MAYBE A MIX IN THE FAR SOUTH MIDDAY INTO
WED AFTERNOON WITH SOME RISE IN TEMPS IN THE BOUNDARY LAYER...BUT
THIS ABOVE FREEZING DEPTH INDICATED BY BUFKIT SOUNDINGS BARLEY
SUPPORT A MIX EVEN IN THOSE AREAS AND EVAPO/DYNAMICAL COOLING
PROCESSES MAY TRANSITION THE MIX BACK TO ALL SNOW EVEN IN THE
SOUTH. WILL ADVERTISE MAINLY SNOW WED INTO WED EVENING WITH LIKELY
POPS FOR MUCH OF THE DAY. AS FOR SNOW AMOUNTS...WILL ADVERTISE
FROM A HALF INCH...UP TO 1.5 INCHES GENERALLY ALONG AND WEST OF A
LINE FROM DUBUQUE..TO THE QUAD CITIES...TO MONMOUTH IL. VARIOUS
SNOW METHODS USING THIS KIND OF CLIPPER FORCING SCENARIO WITH 12:1
LSR/S SUPPORTS A SWATH OF 2+ INCHES CENTERED ON A LINE FROM
WILLIAMSBURG IA...TO WASHINGTON/MT PLEASANT TO NORTHWEST OF MACOMB
IL. DECREASING ACTIVITY TO LIGHT SNOW OR FLURRIES WED NIGHT. PRE-
WAVE LLVL WAA TO DRAW TEMPS INTO THE 30-35 DEGREE RANGE ACRS MUCH
OF THE CWA ON WED...BUT WORRIED EVAPO-COOLING PROCESSES MAY KEEP
THE SOUTH IN THE LOWER 30S. VEERING LLVL FLOW TO COOL ADVECT LATE
WED NIGHT INTO THU MORNING FOR LOWS BACK INTO THE TEENS TO LOWER
20S. STRENGTHENING LLVL COLD ADVECTION MAY MAKE FOR TEMPS TO ONLY
RECOVER 3-8 DEGREES FROM 12Z VALUES FOR TURKEY DAY HIGHS EVEN WITH
SOME INSOLATION....FRESH SNOW COVER TO ALSO TAKE INTO ACCOUNT
UNDER PASSING SFC RIDGE LOBE. THU NIGHT LOWS TO OCCUR DURING THE
EVENING AFTER SUNSET...WITH FLATTENING MEAN STEERING FLOW
SHUTTLING THE NEXT WAVE ACRS THE UPPER MIDWEST TOWARD THE WESTERN
GRT LKS INDUCING LLVL RETURN FLOW AND A STEADY TO SLOW TEMP RISE
AS THU NIGHT PROGRESSES INTO FRI AM. AN OVERRUNNING ISENTROPIC
SNOW EVENT WILL LOOK TO OCCUR SOMEWHERE ACRS THE UPPER MIDWEST
AHEAD OF APPROACHING WAVE LATER THU NIGHT INTO FRI. MOST OF THE
SOLUTIONS KEEP THIS SNOW EVENT TO THE NORTH OF THE LOCAL AREA ACRS
MN AND WI...BUT THE ECMWF IS QUICKER AND FURTHER TO THE SOUTH WITH
LIGHT ACCUMULATING SNOW MAKING IT ACRS AT LEAST THE NORTHERN THIRD
OF THE DVN CWA AFTER MIDNIGHT...POSSIBLY PUTTING DOWN UP TO AN
INCH OF LIGHT FLUFF BY NOON FRI ALONG AN NORTH OF HWY 30. WITH
DISCREPANCIES...FOR NOW WILL JUST KEEP LOW CHC POPS ACRS THE FAR
NORTH ON FRI. HIGH TEMPS MAY REBOUND BACK WELL UP IN THE 30S OR
EVEN LOWER 40S ON FRI IN WAA REGIME TO SOUTH OF THE PERTURBATION
PRESSING ACRS THE WESTERN GRT LKS...AGAIN THIS MORE TRUE WITH THE
MORE NORTHERLY GFS/GEM/UKMET.

SATURDAY THROUGH NEXT MONDAY...A REGIME SHIFT TO WESTERLIES/AT LEAST
TEMPORARILY/...AND STRONG WARM AIR ADVECTION FROM THE SOUTHERN
PLAINS-THERMAL TAP COULD DRIVE TEMPS IN THE 50S ACRS MUCH OF THE
AREA ON SAT. OF COURSE AT THIS TIME OF YEAR...THE SAME PROCESS MAY
INDUCE CLOUDS...DRIZZLE AND POSSIBLY FOG LIMITING THE WARM UP
POTENTIAL. THE WARMER EURO MOS HAS A HIGH OF 60 AT BRL...55 AT MLI
52 AT CID...AND 48 AT DBQ FOR SAT. THIS IN CONTRAST TO THE MEX/GFS
MOS WHICH KEEPS THE AREA IN THE UPPER 30S NORTH TO THE MID 40S IN
THE SOUTH. WILL ADVERTISE A TEMP SCENARIO IN-BETWEEN THE GUIDANCE FOR
NOW AND KEEP SAT DRY. A FROPA WITH A RE-ENFORCING CANADIAN HIGH WILL
THEN LOOK TO DUMP DOWN THROUGH THE AREA LATE SAT NIGHT AND INTO
SUNDAY FOR A COOL DOWN FOR THE SECOND HALF OF THE WEEKEND. SOME
OVERRUNNING RAIN POSSIBLE IN THE SOUTH NORTH OF THE PASSING SFC
BOUNDARY ON SUNDAY...BUT FOR NOW PREFER TO KEEP THE FCST DRY UNTIL
LLVL BAROCLINICITY FOCAL RIBBON GETS BETTER DEFINED IN UPCOMING MODEL
RUNS. LARGE STRONG SFC ANTICYCLONE ACRS THE WESTERN GRT LKS FOR NEXT
MONDAY...WHILE UPPER RIDGING BROADENS UPSTREAM ACRS THE ROCKIES.
  ..12..

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1148 AM CST TUE NOV 25 2014

VFR IS FORECAST THROUGH TONIGHT. AN APPROACHING SHORTWAVE TROUGH
WILL THEN RESULT IN LOWERING CIGS AND VSBYS TO MVFR AT KCID AND
KBRL AFTER 12Z/WED ALONG WITH A CHANCE FOR -SHSN/-SN. THE
ATMOSPHERE WILL BE VERY DRY INITIALLY SO IT WILL TAKE A WHILE TO
SATURATION THE LOWER TO MIDDLE TROPOSPHERE. THE NAM ONLY BRINGS
-SN INTO KBRL BUT THE SREF BRINGS THE PRECIP SHIELD FURTHER NORTH.
ALSO...PRECIP CHANCES WILL INCREASE OUTSIDE THIS TAF PERIOD...AFTER
18Z/WED.

&&

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

$$

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





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