Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 241404
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
904 AM CDT FRI OCT 24 2014

.UPDATE...
ISSUED AT 903 AM CDT FRI OCT 24 2014

CI STREAMING IN FROM THE NORTHERN PLAINS IS NOT HELPING WITH THE
FOG TRENDS THIS MORNING. IN FACT...THE DENSE FOG IS EXPANDING
EASTWARD IN THE WEAK LOW LEVEL CONVERGENT FLOW IN THE SATURATED
LAYER BELOW 925 MB ON THE DVN SOUNDING. HAVE UPDATED TO EXTEND
THE DENSE FOG ADVISORY UNTIL NOON AND HAVE EXTENDED IT EASTWARD
ACROSS THE ENTIRE FORECAST AREA IN A QUICK UPDATE. ON FIRST
LOOK...FOG AND LOW CLOUDS...TO SOME EXTENT...COULD LINGER INTO THE
AFTERNOON AND FURTHER UPDATES FOR A MORE PESSIMISTIC CONDITIONS
THROUGH THE REST OF THE DAY MAY BE NEEDED.

&&

.SYNOPSIS...
ISSUED AT 343 AM CDT FRI OCT 24 2014

LATEST SFC ANALYSIS WAS INDICATING RIDGE LOBE OVERHEAD...WHILE A SFC
TROF AND SOME CYCLONIC FLOW WAS ORGANIZING UPSTREAM FROM SOUTHEASTERN
SD...TO THE OK PANHANDLE. MUCH OF THE CWA SOCKED IN WITH DENSE FOG...
ALTHOUGH THE STRATOCU DECK ACRS NORTHERN IL HELPING KEEP THE FAR
EASTERN CWA IN GOOD VISIBILITY. ALOFT...WATER VAPOR LOOP WAS INDICATING
A LEAD VORT LOBE OVER EASTERN SD INTO CENTRAL NEB...WHILE A MORE
VIGOROUS UPPER WAVE WAS NOTED FURTHER UPSTREAM TO THE WEST OVER
WY.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 343 AM CDT FRI OCT 24 2014

TODAY...WILL LET ONGOING FOG ADVISORY RIDE FOR NOW AND NOT EXPAND
FURTHER TO THE EAST ACRS THE REST OF THE CWA...BUT WILL WATCH
IT/TRENDS EAST OF THE MS RVR THROUGH SUNRISE. AFTER THAT...
CHALLENGING FCST TODAY WITH REGARDS TO CLOUD COVER...PRECIP AND
EFFECT ON TEMPS/WARM UP POTENTIAL. LOOKING AT LATEST SUITE OF FCST
SOUNDINGS...WILL SIDE MORE PESSIMISTIC WITH RESPECT TO CLOUD COVER
TODAY. LOW STRATOCU AND FOG DECKS PROBABLY TO GET TRAPPED UNDER
BUILDING WARM AIR ADVECTION INVERSION FURTHER ALOFT AS THE DAY
PROGRESSES. HIGHER CLOUDS SPILLING IN FROM THE WEST OFF UPSTREAM
WAVES ALSO WILL HINDER LOW CLOUD DECK BREAK UP. THUS WILL MAKE MOST
OF THE CWA MOSTLY CLOUDY TODAY...ALTHOUGH THE SOUTHWESTERN THIRD MAY
GO PARTLY SUNNY THIS AFTERNOON BEHIND THE FIRST PASSING VORT LOBE NOW
ACRS SD/NEB. LIFT OFF THAT WAVE COMING ACRS THE AREA THIS MORNING
PROBABLY ENOUGH TO WRING OUT DRIZZLE...BUT LLVL MOISTURE/CLOUD DEPTH
AT QUESTION TO ALLOW FOR THIS VERY LIGHT PRECIP TO OCCUR. IT MAY GET
CLOSE...BUT FOR NOW WILL LEAVE OUT DRIZZLE MENTION AND JUST STRESS
THE FOG THROUGH MID MORNING. WILL KNOCK DOWN HIGHS SOME MORE...LOW
TO MID 60S FOR THE NORTHEASTERN TWO THIRDS AND MID TO UPPER 60S IN
THE SOUTHWESTERN THIRD WHERE EXPECT SOME AFTERNOON SUNSHINE OR TIMELY
BREAKS IN CLOUD COVER. SOUTH WINDS EXPECTED TO INCREASE AHEAD OF
INCOMING SFC TROF THIS AFTERNOON TOO TO HELP THE WARMING CAUSE. IF
CLOUDS/FOG REMAIN STUBBORN...THESE TEMPS ACRS MANY AREAS WILL STILL
BE TOO WARM AND SOME AREAS MAY NOT GET OUT OF THE 50S. ATTENTION THEN
TURNS TO THE NEXT ROUND OF LIFT COMING THIS AFTERNOON TO THE LEE OF
THE WY VORT MAX. MOISTURE PROGS SUGGEST A WING OF LLVL DEEPENING
MOISTURE LAYER UP ABOVE H85 MB AHEAD OF THIS WAVE...AND COMBINED WITH
THE LIFT OFF THIS SECOND FEATURE...PROBABLY ENOUGH TO PRODUCE SOME
SPOTTY AREAS OF LIGHT RAIN FROM WEST TO EAST MAINLY ALONG AND NORTH
OF I80 THIS AFTERNOON AND INTO EARLY EVENING. WILL GO WITH 20 POPS TO
COVER THE LOW PROBABILITY OF MEASURING...BUT A FEW AREAS IN THE NORTH
MAY GET AT LEAST A HUNDREDTH.

TONIGHT...WILL WALK OUT ANY LINGERING LIGHT RAIN OR DRIZZLE OUT OF
THE NORTHEASTERN CWA BY MID EVENING AS THE LIFT SCOOTS TO THE EAST
WITH PASSING VORT MAX. WINDS TO VEER LIGHT WESTERLY AFTER TROF
PASSAGE...BUT SIGNALS OF LONG ENOUGH PERIODS OF LIGHT WINDS AND SOME
CONVERGENCE AROUND THE TROF AXIS ITSELF MAY FOSTER MORE FOG DEVELOPMENT
BY EARLY EVENING AFTER SUNSET ESPECIALLY ALONG AN NORTH OF I80.
MAY BE ANOTHER ROUND OF LOCALLY DENSE FOG FOR A PERIOD WHILE THE
SFC WINDS STAY LIGHT OR DECOUPLED. FOR NOW WILL GO WITH AREAS OF
FOG THROUGH MIDNIGHT...BUT THEN DO EXPECT SOME INCREASE IN WEST TO
NORTHWEST SFC WINDS INTO EARLY SAT MORNING TO HELP MIX OUT THE FOG
IF IT DOES FORM. SKIES WILL TRY TO CLEAR FROM WEST TO EAST
OVERNIGHT...AND IF SFC WINDS DO NOT INCREASE AFTER MIDNIGHT LIKE
EXPECTED...FOG MAY BECOME WORSE/EXPAND AFTER MIDNIGHT AND INTO
EARLY SAT MORNING. LINGERING HIGHER DPT POOL AND BOUNDARY LAYER
MOISTURE SUPPORTS LOWS IN THE UPPER 40S TO LOW/MID 50S FOR MUCH OF
THE FCST AREA.     ..12..

.LONG TERM...(SATURDAY THROUGH NEXT THURSDAY)
ISSUED AT 343 AM CDT FRI OCT 24 2014

SEASONABLY MILD WITH CHANCES FOR RAIN MONDAY...TURNING COOLER BY
LATE WEEK.

LONG TERM FORECAST CONFIDENCE...FAIR OR AVERAGE WITH PRECIPITATION
EVENT POOR AS EVIDENCE SUGGESTS ALL SOLUTIONS TOO PROGRESSIVE AND
NOT MOIST ENOUGH EARLY NEXT WEEK.  RISK OF ISOLATED THUNDERSTORMS
ARE MARGINAL AND SUGGEST MAY BE ABLE TO REMOVED.  TEMPERATURES MOST
DAYS MAY STILL BE A DEGREE OR TWO WIDER THAN CURRENT DIURNAL RANGE.
COOLING TREND LATE IN THE WEEK SUGGESTS TEMPERATURES WILL NEED
FURTHER LOWERING BY 1 TO 2 CATEGORIES.

OVERVIEW...INITIALIZATION GOOD OVER CONUS WITH PACIFIC ENERGY POORLY
SAMPLED IMPACTING NEXT DISTURBANCE EARLY NEXT WEEK. VERIFICATION AND
RUN TO RUN VARIANCE CLEARLY SUGGEST HI-RES ECMWF SHOULD RECEIVE
HIGHEST WEIGHT SUPPORTING HIGHER POPS EARLY NEXT WEEK WITH WIDESPREAD
PRECIPITATION TOTALS BETWEEN A TENTH TO OVER A HALF INCH SUGGESTED.

SATURDAY AND SUNDAY...SPLENDID LATE OCTOBER WEATHER WITH FAIR SKIES
AND WIDE DIURNAL TEMPERATURE RANGES.  HIGHS MAY BE A DEGREE OR TWO
TOO LOW AND MINS A DEGREE OR TWO TOO MILD FOR LATER SHIFTS.  LIGHT
WINDS TO MAKE FOR GOOD DAYS FOR FALL OUTSIDE ACTIVITIES.

SUNDAY NIGHT THROUGH MONDAY NIGHT...NEXT DISTURBANCE TO ARRIVE LATE
MONDAY WITH WARM SOUTH WINDS AND CLOUDS TO KEEP LOWS MID TO UPPER
50S SUNDAY NIGHT WITH ISOLATED SHOWERS ALONG HIGHWAY 20 CORRIDOR.
MONDAY...SOUTH TO SOUTHWEST WINDS OF 10 TO 20+ MPH AND DEEP MIXING
SUPPORTS PROBABLY ONE OF OUR LAST FALL DAYS WELL INTO THE 70S.  LOCAL
TOOLS SUPPORT SOME UPPER 70S MID TO SOUTH SECTIONS.  CLOUDS TO
INCREASE LATE MONDAY WITH RAIN AND RAIN SHOWERS AND POSSIBLY IF
EVERYTHING PHASES...AN ISOLATED STORM...MAINLY SE 1/2 SECTIONS AS
LATER SHIFTS WILL BE ABLE TO REASSESS THIS.  HAVE CHANCE POPS BUT
JET STRUCTURE AND PHASING SUGGEST LIKELY POPS AND RAIN TOTALS
UNDERDONE WHICH SHOULD BE BETTER CLARIFIED NEXT 24 HOURS.  LOCAL RAIN
TOOLS AND TECHNIQUES USING HI-RES ECMWF SUPPORTS WIDESPREAD .1 TO 50+
INCH TO ISOLATED .75 INCH AMOUNTS. FRONTAL PASSAGE LATE TO LIKELY
CREATE A DECENT LOW TEMPERATURE GRADIENT WITH TIMING A MAIN ISSUE.
CURRENT UPPER 40S NW TO UPPER 50S ADEQUATE AT THIS TIME.

TUESDAY THROUGH THURSDAY...NW FLOW TO BRING COOLER AIR WITH FAIR
SKIES AND DRY CONDITIONS.  DRY UPPER DISTURBANCE TO BRING COLDER AIR
BY THURSDAY WITH RISK FOR LATER SHIFTS MINS ARE 2 TO 5 DEGREES TOO
MILD AND HIGHS POSSIBLY UP TO 5 DEGREES TOO MILD ON THURSDAY.  NW
WINDS ON THURSDAY MAY NEED RAISING WITH STRONGER BUT DRY COOL FRONT
WITH REINFORCING AIR FROM CANADA.    NICHOLS

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 821 AM CDT FRI OCT 24 2014

LOW CLOUDS AND IFR TO LIFR FOG HAVING BIG IMPACT ON ALL TAF SITES
THIS MORNING...IT MAY BE OPTIMISTIC TO IMPROVE AFTER 15Z. WITH
INCREASING SOUTH WINDS THE BRL SITE SHOULD BE THE FIRST TO IMPROVE
BY MID MORNING...MLI TO MVFR BY 17-18Z...BUT CID AND DBQ AT SOME
RISK OF EXTENDING INTO THE AFTERNOON. EVEN AFTER A TEMPORARY
AFTERNOON RISE TO MVFR...THE MLI...CID...AND DBQ SITES COULD SINK
BACK TO IFR OR EVEN LIFR CIGS AND VSBYS WITH FOG AFTER SUNSET.
SOME LIGHT RAIN POSSIBLE THIS AFTERNOON AND EVENING ALONG AND
NORTH OF I80. BANKING ON SOME INCREASE IN WEST WINDS AFTER
MIDNIGHT BEHIND PASSING SFC TROF TO HELP MIX OUT WHAT EVER FOG OR
LOW CIGS THAT REFORM OR PERSIST DURING THE EVENING...BUT THAT MAY
BE OPTIMISTIC AS WELL IF STRONGER WESTERLY FLOW REMAINS MORE ALOFT
INTO EARLY SAT MORNING.    ..12..


&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...DENSE FOG ADVISORY UNTIL NOON CDT TODAY FOR BENTON-BUCHANAN-
     CEDAR-CLINTON-DELAWARE-DES MOINES-DUBUQUE-HENRY IA-IOWA-
     JACKSON-JEFFERSON-JOHNSON-JONES-KEOKUK-LEE-LINN-LOUISA-
     MUSCATINE-SCOTT-VAN BUREN-WASHINGTON.

IL...DENSE FOG ADVISORY UNTIL NOON CDT TODAY FOR BUREAU-CARROLL-
     HANCOCK-HENDERSON-HENRY IL-JO DAVIESS-MCDONOUGH-MERCER-
     PUTNAM-ROCK ISLAND-STEPHENSON-WARREN-WHITESIDE.

MO...DENSE FOG ADVISORY UNTIL NOON CDT TODAY FOR CLARK-SCOTLAND.

&&

$$

UPDATE...SHEETS
SYNOPSIS...12
SHORT TERM...12
LONG TERM...NICHOLS
AVIATION...12






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