Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 112127
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
327 PM CST THU FEB 11 2016

.SYNOPSIS...
ISSUED AT 327 PM CST THU FEB 11 2016

HIGH PRESSURE CENTERED OVER THE EASTERN CWA THIS AFTERNOON AS
LEADING TO CLEAR SKIES AND DRY WEATHER FOR MOST OF THE AREA. A
FAST MOVING CLIPPER IS FORECAST TO AFFECT THE AREA LATER TODAY AND
TONIGHT AND WILL BE THE MAIN FORECAST CONCERN IN THE SHORT TERM
FORECAST.

&&

.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 327 PM CST THU FEB 11 2016

MAIN FORECAST CONCERN FOR THE SHORT TERM ARE THE CHANCES FOR SNOW
ASSOCIATED WITH A FAST CLIPPER ACROSS THE AREA TODAY. DRY AIR IN
PLACE WITH THE HIGH OVERHEAD WILL LIMIT OVERALL SNOWFALL TOTALS TO
AROUND AN INCH...WITH LOCALLY HIGHER AMOUNTS JUST OVER AN INCH.
HIRES GUIDANCE IS IN GOOD AGREEMENT THAT THIS WILL START NEAR 00Z
AND BE OUT OF THE AREA BY 08Z.

GUIDANCE TODAY HELD STRONG WITH THE CONSENSUS ON TIMING AND
STRONGEST FORCING WILL REMAIN ACROSS OUR FAR SOUTHERN ZONES. WWD
HAS AROUND AN INCH OF SNOW FOR THIS AREA AND OUR FORECAST
REPRESENTS THIS. LATEST RUNS OF THE HRRR SUGGESTS THAT THE BEST
SNOW WILL BE OUT OF THE AREA BY 06Z WITH LINGERING FLURRIES
THROUGH 09Z ACROSS THE FAR SOUTHERN CWA. WINDS WILL REMAIN LIGHT
SO LITTLE TO NO IMPACTS ARE EXPECTED FROM THIS SNOW. ANY SNOW THAT
ACCUMULATES SHOULD BE DONE BY THE EARLY HOURS.

FRIDAY WILL BE QUIET AND SLIGHTLY WARMER..WITH CLEARING SKIES.

.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 327 PM CST THU FEB 11 2016

FRIDAY NIGHT...LATEST SUITE OF 12Z RUN MODELS SUGGEST 1045 MB ARCTIC
HIGH PRESSURE STILL ON TRACK TO SURGE DOWN THE UPPER TO MID MS RVR
VALLEY FRI NIGHT INTO SAT WITH A SCOURING EFFECT. THIS FEATURE TO
COLD DUMP LLVL TEMPS/THICKNESS VALUES TO PRODUCE SUB-ZERO LOWS ACRS
MOST OF THE CWA...BUT SOME CONCERN THAT ONGOING MIXING SFC WINDS IN
INCOMING HIGH PRESSURE GRADIENT TO LIMIT A COMPLETE BOTTOM OUT.
BUT DUE TO BRUTE FORCE COLD AIR ADVECTION...WILL STILL GO WITH LOWS
FROM 5 TO NEAR 10 BELOW ZERO ACRS THE NORTHWESTERN THIRD OF THE
CWA...0 TO 5 BELOW ALONG AND NORTH OF I80...AND TO THE LOW SINGLE
DIGITS ABOVE ZERO IN THE SOUTHERN CWA. SFC WINDS DECREASING TO 7-10
MPH TOWARD SUNRISE SAT STILL TO PRODUCE ADVISORY LEVEL WIND CHILLS
ACRS AT LEAST THE NORTHWESTERN THIRD OF THE DVN CWA...AND POSSIBLY
ALONG THE HWY 20 CORRIDOR IN NW IL.

SATURDAY AND SUNDAY...THE ARCTIC HIGH OVERHEAD WILL MAKE FOR
TEMPORARY CLEAR AND CALM/LIGHT WIND CONDITIONS FOR FIRST PART OF THE
DAY SAT...WITH HIGH CLOUDS ON THE INCREASE AS THE AFTERNOON
PROGRESSES. THIS AHEAD OF THE ORGANIZING SHORT WAVE UPPER TROF THAT
WILL LOOK TO PROPAGATE TOWARD THE SOUTHWESTERN GRT LKS AND MID MS
RVR VALLEY ON SUNDAY IN BROADENING WEST-NORTHWESTERLY STEERING FLOW.
THE VARIOUS MEDIUM RANGE SOLUTIONS SUGGEST SOME TYPE OF ASSOCIATED
WARM AIR ADVECTION WING OF SNOW WILL LOOK TO TRY TO GET INTO THE
WESTERN OR SOUTHWESTERN CWA BY EARLY SAT EVENING...BUT FEEL MODELS
MAY BE TOO QUICK WITH THIS TAKING INTO ACCOUNT STRENGTH OF DRY SFC
RIDGE AXIS STILL ON THE MOVE OVER AND EAST OF THE CWA AT THAT TIME.
BUT BY MIDNIGHT SAT NIGHT...BOTH THE 12Z RUN ECMWF AND GEM SUGGEST
SOME LIGHT SNOW ACCUMS STARTING TO TAKE PLACE ALREADY IN THE FAR
SOUTHWESTERN CWA. AGAIN SIDING WITH THE 12Z GEM/ECMWF WHICH ARE IN
DECENT AGREEMENT...THE WAA WING OF SNOW AHEAD OF THE MAIN UPPER TROF
WILL LOOK TO CONTINUE TO SPREAD EASTWARD ACRS MUCH OF THE WESTERN
2/3S OF THE CWA THROUGH 12Z SUNDAY...BUT MAY GET ERODED SOME AS IT
DOES BY ONGOING DRY AIR IN PLACE AND ALSO SOME IMPACT OF MUCH OF THE
INITIAL LIFT GOING INTO THE TOP-DOWN SATURATION PROCESS. THE LATEST
GEM MAY HAVE THE BEST HANDLE ON THIS IDEA WITH JUST A DUSTING TO
HALF INCH WEST OF THE MS RVR BY 12Z SUNDAY...BUT WILL GO WITH A FEW
TENTHS TO NEAR AN INCH SOUTHWEST OF A LINE FROM DBQ...TO THE QUAD
CITIES...AND TO MACOMB IN WESTERN IL.

THEN THE MAIN SNOW EVENT WITH THE UPPER TROF WILL LOOK TO OCCUR ON
SUNDAY AND WILL CONTINUE TO ADJUST POPS UP INTO LIKELY OR EVEN
CATEGORICAL. BUT THE 12Z RUN AMERICAN MODELS/ESPECIALLY THE 12Z GFS/
WHICH HINT AT HIGH END ADVISORY OR EVEN LOW END WARNING CRITERIA
AMOUNT SNOWS BY SUNDAY EVENING COMBINING THE TWO SNOW MAKING
PROCESSES...SEEM TOO WET...TOO STRONG LOOKING AT MID AND UPPER LEVEL
JET DYNAMICS MORE FAVORABLE TO THE SOUTH...AND THEIR DEEP SATURATION
IN THE DENDRITIC GROWTH ZONE FOR MUCH OF SUNDAY MORNING INTO EARLY
AFTERNOON. SO CURRENTLY FAVOR A BLEND OF THE 12Z GEM/ECMWF MOISTURE
AND FORCING PROFILES WHICH SUGGEST MOST OF THE CWA TO GET 1-3 OR 2-4
INCHES OF SNOW BY SUNDAY EVENING. INCREASING SOUTH WINDS OF 15-20
MPH MAY PRODUCE SOME DRIFTING TROUBLE BY SUNDAY AFTERNOON AS
WELL...SO THERE MAY BE A NEED FOR AN EVENTUAL ADVISORY EVEN WITH THE
LIGHTER AMOUNTS PRODUCED BY THESE FAVORED SOLUTIONS. STILL 1-3 MORE
MODEL RUNS NEEDED TO FURTHER DEFINE THIS SNOW EVENT FOR MORE
CONFIDENCE.

MONDAY THROUGH NEXT THU...AS THE PASSING TROF CONTINUES TO EVOLVE
ALONG AND EAST OF THE REGION EARLY NEXT WEEK..RESULTANT MAJOR STORM
SHOULD TAKE OFF WELL TO THE EAST/SOUTHEAST OF LOCAL AREA OF CONCERN.
BUT THERE MAY BE SOME NUISANCE LIGHT SNOW AT TIMES ACRS THE AREA IN
THE WAKE OF THE MAIN SYSTEM...OR EVEN A SECONDARY WEAK CLIPPER LATE
MONDAY INTO TUE. LONGER RANGE INDICATIONS THEN SUGGEST THE CLIPPER
INDUCING NORTHWESTERLIES WILL EVENTUALLY GIVE WAY TO MILDER UPPER
RIDGING BY MID TO LATE NEXT WEEK...BUT THE TREND HAS BEEN TO DELAY
IT/S ARRIVAL ESPECIALLY IF RE-ENFORCING TROFFINESS ESTABLISHES ACRS
THE WESTERN GRT LKS TUE INTO WED LIKE SOME OF THE LATEST ENSEMBLES
SUGGEST. ..12..

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1132 AM CST THU FEB 11 2016

VFR CONDITIONS GIVING WAY TO MVFR CIGS AND POSSIBLY IFR VSBYS
DURING SNOW LATE THIS AFTERNOON AND THROUGH THE EVENING IS
EXPECTED AT MOST TAF SITES. BRL HAS THE BEST CHANCE FOR SNOW.
OTHERWISE WINDS SHOULD TURN TO THE SW AND THEN THE WNW LATE IN THE
PERIOD INTO TOMORROW WHERE SOME STRONG SUSTAINED WINDS ARE
POSSIBLE WITH GUSTS POSSIBLY TO 25KT. VFR CONDITIONS SHOULD RETURN
BY 09Z AT MOST TAF SITES.


&&

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

$$

SYNOPSIS...GIBBS
SHORT TERM...GIBBS
LONG TERM...12
AVIATION...GIBBS


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