Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 240439
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1139 PM CDT THU OCT 23 2014

.UPDATE...
ISSUED AT 757 PM CDT THU OCT 23 2014

AS IF OFTEN THE CASE...THE FOG DEVELOPED AT DENSE LEVELS VERSUS
GRADUALLY LOWERING TO THEM. THUS...THE DENSE FOG ADVISORY HAS BEEN
STARTED NOW RATHER THAN WAITING UNTIL 1 AM. THIS DENSE FOG WILL
SLOWLY EXPAND EAST OVER THE CWA TONIGHT...AND A POSSIBLE EXPANSION
OF THE ADVISORY IS BEING CONSIDERED.
ERVIN

&&

.SYNOPSIS...
ISSUED AT 325 PM CDT THU OCT 23 2014

12Z UA ANALYSIS HAS AN 850MB LOW OVER THE GREAT LAKES WITH AN UPPER
LEVEL DISTURBANCE FROM MINNESOTA INTO NORTHEAST KANSAS.
RADAR/SATELLITE TRENDS THROUGH MID AFTERNOON SHOW SHOWERS ACROSS
NORTHEAST IOWA AND NORTHWEST ILLINOIS. SKIES WERE SLOWLY CLEARING
FROM THE WEST ACROSS IOWA.

18Z SFC ANALYSIS HAS AN IMPLIED FRONT/BOUNDARY FROM NEAR KJEF TO
KDLH WITH A COLD FRONT FROM NEAR KRST TO KFNB. DEW POINTS WERE IN
THE 40S ACROSS THE GREAT LAKES WITH A TONGUE OF 50 DEW POINTS FROM
THE SOUTHERN PLAINS INTO SOUTHEAST MINNESOTA.

&&

.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 325 PM CDT THU OCT 23 2014

BASED ON RADAR TRENDS...ISOLATED TO SCATTERED SHOWERS WILL CONTINUE
THROUGH SUNSET WITH THE BEST CHANCES NORTH OF I-80 AND GENERALLY
EAST OF HIGHWAY 61.

AFTER SUNSET...CLEARING WILL SLOWLY MOVE EAST TOWARD THE MISSISSIPPI
AS HIGH PRESSURE BUILDS INTO IOWA. THOSE AREAS THAT SAW RAIN DURING
THE DAY MAY SEE SOME PATCHY FOG DEVELOP AS THE SKIES CLEAR.

AFTER MIDNIGHT...SKIES WILL CONTINUE TO CLEAR AND WINDS BECOME
LIGHT. FOG WILL DEVELOP AND BECOME FAIRLY WIDESPREAD. AS A RESULT...
A DENSE FOG ADVISORY HAS BEEN ISSUED FOR MUCH OF THE AREA. DEPENDING
UPON HOW THE FOG DEVELOPS...THE AREAL COVERAGE OF THE ADVISORY MAY
NEED TO BE EXPANDED.

DENSE FOG SHOULD BE SEEN ACROSS MUCH OF THE AREA AT SUNRISE FRIDAY
WITH AREAS OF FOG ELSEWHERE. THE FOG SHOULD BEGIN LIFTING TOWARD THE
END OF THE MORNING COMMUTE AND BURN OFF BY LATE MORNING.

FRIDAY AFTERNOON SHOULD BE QUIET AND DRY ACROSS THE AREA. MAX
TEMPERATURES ON FRIDAY WILL BE DEPENDENT ON WHEN THE FOG AND LOW
CLOUDS BURN OFF. IF THE LOW CLOUDS HOLD ON LONGER...THEN HIGH
TEMPERATURES FOR FRIDAY WOULD NEED TO BE LOWERED.

.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 325 PM CDT THU OCT 23 2014

FRIDAY NIGHT...GENERAL SUGGESTION FROM MODELS OF PSEUDO WARM FRONTAL
PASSAGE IN THE EVENING WITH STRONG LOW LEVEL THETA-E ADVECTION
CONDUCIVE FOR LOW CLOUDS AND POSSIBLY AREAS OF DRIZZLE OR PATCHY VERY
LIGHT RAIN AND FOG. COOL FRONT TO FOLLOW OVERNIGHT SWEEPING LOW LEVEL
MOISTURE OUT AND THUS CLEARING SKIES. LOWS COOLEST NORTHWEST (UPPER 40S
TO AROUND 50) TO WARMEST FAR SOUTH (MID 50S).

SATURDAY THROUGH SUNDAY...SURFACE HIGH PRESSURE TO DOMINATE MUCH OF THE
PERIOD WITH DRY AND CONTINUED ABOVE NORMAL TEMPS... WITH MAXES IN THE
60S TO LOWER 70S (SOUTHERN CWA). THE HIGH WILL GRADUALLY SHIFT TO
THE EAST DURING DAY ON SUNDAY WITH INCREASING E/SE WINDS 10-20+ MPH
AHEAD OF DEVELOPING WARM FRONT. STRONG LOW LEVEL MOISTURE GRADIENT
DEVELOPS ACROSS CWA DURING SUNDAY PM... BUT FAIRLY SHALLOW DEPTH COUPLED
WITH MID LEVEL RIDGING PRECLUDES ANY MENTION OF PCPN SUNDAY PM ATTM.
SUNDAY NIGHT...WARM FRONT LOOKS TO LIFT THROUGH THE CWA WITH CONTINUED
STRONG MOISTURE TRANSPORT ON 40-45+ KT LOW LEVEL JET SUPPORTIVE OF CHANCE
OF SHOWERS ACROSS THE NORTHERN CWA SUNDAY EVENING. REST OF SUNDAY NIGHT
WILL BE DRY AND RATHER MILD IN WARM SECTOR WITH LOWS WELL INTO THE 50S
TO LOWER 60S ON SOUTHERLY WIND AROUND 10 KTS AND GUSTY.

MONDAY THROUGH THURSDAY...CHANCES FOR SHOWERS AND POSSIBLY A FEW STORMS
EXISTS MONDAY THROUGH TUESDAY AS WESTERN TROUGH MOVES EAST THROUGH THE
REGION. STILL CONSIDERABLE MODEL RUN TO RUN VARIANCES ON STRENGTH...
TIMING AND TRACK OF ENERGY WHICH WILL HAVE BIG IMPACTS ON PCPN AMOUNTS
AND TIMING. HI-RES ECMWF HAS SHOWN THE GREATEST CHANGES OVER PAST SEVERAL
RUNS SHIFTING MAIN TROUGH 500-700 MILES NORTH FROM SOUTHERN PLAINS TO
NOW OVER WESTERN GREAT LAKES BY TUESDAY EVENING CLOSER TO GFS RUNS PAST
FEW DAYS. GFS HAS ACTUALLY SHOWN BETTER RUN TO RUN CONTINUITY WITH THIS
SYSTEM ALTHOUGH IT TOO IS SHOWING SOME CHANGES ESPECIALLY IN STRENGTH.
MONDAY MAY BE WITHOUT MUCH IN WAY OF PCPN AND MILD WITH CWA IN
CAPPED PRE-FRONTAL WARM SECTOR WITH HIGHS WELL ABOVE NORMAL AND MANLY IN
THE LOWER TO MIDDLE 70S. RAIN CHANCES WOULD THEN LOOK TO INCREASE
MARKEDLY MONDAY NIGHT INTO TUESDAY WITH COLD FRONT AND MAIN DYNAMICS WITH
TROUGH... WITH WIDESPREAD MODERATE RAIN AMOUNTS POSSIBLE AS IT LOOKS RIGHT
NOW BUT AGAIN THIS DEPENDENT ON STRENGTH OF FORCING AND MOISTURE WITH
IMPACTS TO TRACK/STRENGTH OF ENERGY. IN WAKE OF TROUGH PASSAGE...INDICATION
OF QUASI-ZONAL FLOW SETTING UP FAVORING DRIER SIDE WITH TYPICAL FALL
ROLLER COASTER RIDE ON TEMPS MID TO LATE NEXT WEEK. GFS AND ECMWF ARE
SUGGESTING POTENTIAL FOR STRONGER COLD FRONT AND MUCH COLDER TEMPS LATE NEXT
WEEK.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1123 PM CDT THU OCT 23 2014

A DENSE FOG AND VERY LOW IFR CIG EVENT WILL BEGIN THE PERIOD...AND
LAST WELL INTO FRIDAY MORNING. CONFIDENCE IS LOW ON WHEN THE
MINIMUM FOG/CIGS WILL LIFT...MAYBE AS LATE AS 17Z FRIDAY...BUT
WILL SHOW SOME IMPROVEMENT BEYOND MINIMUMS/ 1/4SM FG VV001 AFTER
15Z. IN THE WAKE OF THE FOG...SOME MVFR STRATUS IS POSSIBLE
THROUGH THE DAY FRIDAY...AGAIN LOW CONFIDENCE ON HOW THIS PLAYS
OUT SINCE MODELS EITHER DON`T HAVE IT AT ALL OR ARE HAMMERING THE
AREA WITH IFR THROUGH THE ENTIRE 24 HOUR PERIOD NOW. SHOULD STATUS
LINGER...ANOTHER FOG EVENT WITH STRATUS IS POSSIBLE FRIDAY NIGHT.
SINCE IS MOST LIKELY IN NORTHERN IOWA...I HAVE INTRODUCED ANOTHER
PERIOD OF IFR WEATHER TO THE DBQ TAF AFTER 00Z/25.
ERVIN

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...DENSE FOG ADVISORY UNTIL 10 AM CDT FRIDAY 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 10 AM CDT FRIDAY FOR HANCOCK-HENDERSON-
     JO DAVIESS-MERCER-ROCK ISLAND.

MO...DENSE FOG ADVISORY UNTIL 10 AM CDT FRIDAY FOR CLARK-SCOTLAND.

&&

$$

UPDATE...ERVIN
SYNOPSIS...08
SHORT TERM...08
LONG TERM...05
AVIATION...ERVIN






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