Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 122332
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
632 PM CDT FRI SEP 12 2014

.SYNOPSIS...
ISSUED AT 323 PM CDT FRI SEP 12 2014

LATEST SFC ANALYSIS WAS INDICATING SEASONABLY STRONG 1035 MB HIGH
PRESSURE CENTER ACRS THE WEST CENTRAL PLAINS...WITH BROAD RIDGING OF
THE CENTER BACK ACRS THE UPPER MS RVR VALLEY AND NORTHWESTERN GRT
LKS. IMPRESSIVE H85 MB RIDGE GENERALLY LOCATED IN THE SAME
LOCATION...WITH A LARGE POOL OF 0C OR COLDER AIR AT THAT LEVEL. 12Z
UPPER AIR ANALYSIS INDICATED RATHER TIGHT H85 MB BAROCLINIC RIBBON
FROM ACRS THE TX PANHANDLE....TO THE SOUTHEASTERN GRT LKS. ALOFT...
WATER VAPOR IMAGERY WAS INDICATING VIGOROUS UPPER LEVEL WAVE ACRS
NORTHWESTERN NEB INTO NW WI ATTM...WITH A SECONDARY WAVE/VORT MAX
LURKING FURTHER UPSTREAM ACRS THE PACIFIC NORTHWEST. OVERRUNNING/
ISENTROPIC LIGHT RAIN EVENT INDUCED BY THE UPPER LEVEL WAVE
ONGOING...WITH BULK OF IT ON TRACK TO BE EAST OF THE DVN CWA BY
6-7 PM CDT.

&&

.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 323 PM CDT FRI SEP 12 2014

TONIGHT...AS MENTIONED ABOVE...WILL WALK OUT BACK EDGE OF MAIN RAIN
SHIELD OUT IF THE EASTERN CWA FROM 23Z-01Z...WITH JUST SECONDARY
SPOTTY AREAS OF LIGHT RAIN/SPRINKLES ROTATING DOWN OUT OF SOUTHERN MN
AND FAR NORTHERN IA ACRS THE NORTHEASTERN 2/3S FCST AREA THROUGH
EARLY EVENING. WILL KEEP ISOLATED/SLIGHT CHC POPS GOING ACRS THESE
AREAS THROUGH AT LEAST 02Z THIS EVENING...ALTHOUGH AGREE WITH
SEVERAL HIRES MODEL SOLUTIONS THAT SUGGEST MUCH OF THIS ACTIVITY TO
DIMINISH AS IT TRIES TO MAKE IT DOWN HERE. NICE POST-WAVE WEDGE OF
DRYING SUBSIDENCE ALSO SEEN ON W/V IMAGERY ROTATING THIS WAY OUT OF
THE NORTHWESTERN PLAINS...SHOULD BE THE MAIN CLEARING AGENT LATER
THIS EVENING AND INTO THE OVERNIGHT. THE UPSTREAM RIDGE AXIS ACRS
SD AND WESTERN MN TO SLIDE DOWN ACRS THE AREA AFTER MIDNIGHT
BRINGING WITH IT LIGHT WESTERLY SFC WIND REGIME OF UNDER 5 KTS. THIS
COMBINED WITH CLEARING AND COLD POOL ALREADY PRETTY MUCH IN PLACE...
SUPPORTS A WELL ADVERTISED NEAR RECORD COLD NIGHT ACRS MUCH OF THE
DVN CWA. H85 MB RIDGE COOL RULE SUPPORTS WIDESPREAD LOWS IN THE MID
TO UPPER 30S...AND IF IT WAS A DRIER SFC LAYER THE SAME AIRMASS
WOULD EVEN SUPPORT SOME LOWER 30S IN THE NORTHERN AND NORTHWESTERN
DVN CWA. ONGOING FCST LOW TEMPS STILL LOOK ON TARGET AND WILL MAKE
LITTLE IF ANY CHANGE. WILL ALSO KEEP WITH THE IDEA OF STILL WARM AND
MOIST SOIL FULL OF LATENT HEAT WILL LIMIT MUCH OF ANY GROUND FROST.
IF IT OCCURS...IT SHOULD BE MAINLY ON ELEVATED HARD SFC/S SUCH AS
CAR WINDOWS/METAL AND ROOFS. ALTHOUGH MAY INTRODUCE PATCHY FROST IN THE FAR
NORTHWESTERN FCST AREA WHERE WE ARE CURRENTLY ADVERTISING LOW TEMPS
IN THE MID 30S...WILL NOT BE ISSUING ANY FROST HEADLINES WITH LIMITED
IMPACT EXPECTED. WILL KEEP PATCHY FOG WORDING WITH AMBIENT TEMPS
COOLING TOWARD THE DPTS...WITH RIVER VALLEYS AND OTHER SATURATED LOW
LYING AREAS MOST PRONE TO SHALLOW LAYER FOG.

SATURDAY...BOUT OF COOL CORE SFC AND UPPER RIDGING TO MAKE FOR A
MAINLY SUNNY DAY WITH HIGHS IN THE UPPER 50S TO LOWER 60S. CU RULE
SUGGESTS SCTRD AMBIENT CELLULAR CU TO DEVELOP BY LATE MORNING
WHICH WOULD NOT RUIN SUNNY WORDING...BUT SOME CONCERN CU COULD NEAR
BROKEN LEVELS SUCH AS WHAT IS GOING ON NOW IN THE EASTERN DAKOTAS
WHICH WOULD BE MORE CHARACTERISTIC OF MOSTLY TO PARTLY SUNNY.  ..12..

.LONG TERM...(SATURDAY NIGHT THROUGH NEXT FRIDAY)
ISSUED AT 323 PM CDT FRI SEP 12 2014

THE NEXT CHANCE FOR RAIN IS STILL CENTERED ON THE LATE SUNDAY NIGHT
INTO MONDAY MONDAY TIMEFRAME. LOWER CONFIDENCE CHANCES FOR RAIN DO
NOT APPEAR AGAIN UNTIL LATE FRIDAY. OTHERWISE...THE MAIN FOCUS IS ON
TEMPERATURES THAT ARE LIKELY TO REMAIN BELOW TO WELL BELOW NORMAL
THROUGH AT LEAST THE MIDDLE OF NEXT WEEK.

FORECAST CONFIDENCE IS ABOVE AVERAGE WITH GOOD MODEL AGREEMENT
THROUGH ABOUT THE MIDDLE OF NEXT WEEK. FROM ABOUT THURSDAY
ONWARD...THE 12Z GFS BECOMES MORE PROGRESSIVE AND FASTER THAN THE
ECMWF WITH THE BREAKDOWN OF THE NW FLOW AND FOLLOWING UPPER LEVEL
TROUGH THAT WOULD AFFECT THE AREA WITH POSSIBLE RAIN NEXT WEEKEND.
WARM ADVECTION TYPE PRECIPITATION IS SUGGESTED AS EARLY AS FRIDAY
AFTERNOON FOR ESPECIALLY THE NW...WHERE CHANCE POPS ARE INTRODUCED.

THIS SATURDAY NIGHT THROUGH SUNDAY...HIGH PRESSURE SHIFTS EAST INTO
THE GREAT LAKES AND OHIO VALLEY...LEADING TO A LIGHT SOUTHERLY
RETURN FLOW OVER THE AREA. WINDS SHOULD BE LIGHT ENOUGH SATURDAY
NIGHT UNDER MOSTLY CLEAR SKIES TO ALLOW RADIATIONAL COOLING AND LOWS
IN THE LOWER 40S...WITH A FEW POCKETS OF UPPER 30S POSSIBLE OVER FAR
EAST CENTRAL IA INTO NW IL. DEEPER MIXING INTO WARMING TEMPERATURES
ALOFT SUNDAY SHOULD RETURN HIGHS TO THE MID TO UPPER 60S...WHICH
WOULD STILL BE 10 DEGREES BELOW NORMAL.

WIDESPREAD TENTH TO QUARTER INCH RAINFALL AMOUNTS LOOK LIKELY FROM
LATE SUNDAY NIGHT THROUGH AT LEAST EARLY MONDAY AFTERNOON AS THE
NEXT UPPER SYSTEM AND WEAK SURFACE FRONTAL PASSAGE SPREADS MAINLY
LIGHT RAIN OVER THE AREA. WITH INCREASING CONFIDENCE...POPS
HAVE BEEN RAISED TO LIKELY ACROSS THE SOUTH. BASED ON CURRENT
TIMING..THE CLOUDS AND PRECIPITATION SHOULD LIMIT HIGHS TO THE LOWER
TO MID 60S. ELEVATED INSTABILITY LOOKS SUFFICIENT ENOUGH TO KEEP A
MENTION OF ISOLATED THUNDERSTORMS ACROSS THE SOUTH.

COOL HIGH PRESSURE FOLLOWS FOR MONDAY NIGHT THROUGH TUESDAY...
CONTINUING THE WELL BELOW NORMAL TEMPERATURES. A SLOW MODERATING
TREND THEN FOLLOWS THROUGH LATE NEXT WEEK UNDER A NW FLOW ALOFT.
THIS IS LIKELY TO RETURN TEMPERATURES TO HIGHS IN THE 70S THU AND
FRI...WHILE LOWS RECOVER FROM THE 40S TO THE 50S.    SHEETS

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 619 PM CDT FRI SEP 12 2014

CIGS TO CONTINUE LIFTING TO VFR THIS EVE BEFORE CLEARING AS HIGH PRESSURE
BEGINS TO BUILD INTO THE REGION. PATCHY SHALLOW GROUND FOG WILL BE
POSSIBLE LATE TONIGHT WITH STEEPENING LOW LEVEL INVERSION AND RESIDUAL
MOISTURE FROM RECENT LIGHT RAIN. ANTICIPATE SCT-BKN CU ON SATURDAY WITH
INITIAL BASES MVFR BEFORE LIFTING TO VFR BY MIDDAY. NORTH WINDS AROUND
10 KTS TO BECOME LIGHT NORTHWEST TONIGHT...WITH LIGHT AND VARIABLE WINDS
SATURDAY AS HIGH PRESSURE BUILDS OVERHEAD.

&&

.CLIMATE...
ISSUED AT 323 PM CDT FRI SEP 12 2014

RECORD LOWS FOR SEPTEMBER 13...

MOLINE.........36 IN 1902
CEDAR RAPIDS...35 IN 1975
DUBUQUE........35 IN 1953
BURLINGTON.....34 IN 1902

&&

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

$$

SYNOPSIS...12
SHORT TERM...12
LONG TERM...SHEETS
AVIATION...05
CLIMATE...12





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