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000
FXUS63 KDVN 151730
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1230 PM CDT SAT JUN 15 2013

.UPDATE...
ISSUED AT 632 AM CDT SAT JUN 15 2013

MCV IS QUITE NOTICEABLE ON RADAR AS THE DROP IN RETURNS PASSING
BETWEEN KDBQ/KMLI. THE NEWEST RAP TRENDS HAS THIS FEATURE EXITING
THE CWFA BY MID MORNING WHICH IS EXPECTED TO CORRESPOND WITH AN
END TO THE PRECIPITATION.

DRY CONDITIONS SHOULD THEN BE SEEN FROM LATE MORNING THROUGH EARLY
AFTERNOON DUE TO BUILDING HEIGHTS ALOFT. DIURNAL HEATING WILL
DESTABILIZE THE ATMOSPHERE DURING THE AFTERNOON AND LEFT OVER
BOUNDARIES FROM THE NOCTURNAL CONVECTION WILL PROVIDE THE FOCUS
FOR DIURNAL CONVECTION DURING THE AFTERNOON. TRENDS IN THE FCST
SOUNDINGS FROM THE RAP SUGGEST CONVECTIVE TEMPERATURES IN THE
UPPER 80S AND 90S AND A CAP IN PLACE. IF CORRECT...THEN CONVECTION
WOULD HAVE TO WAIT UNTIL EVENING WITH THE APPROACH OF THE NE/KS
SHORTWAVE AND THE NEWLY CREATED MCS.

PRELIMINARY DATA OFF THE 12Z SOUNDING SUGGESTS A CONVECTIVE
TEMPERATURE IN THE LOWER 80S. ASSUMING THIS NUMBER WILL INCREASE
SLIGHTLY DURING THE DAY...IT WOULD STILL BE IN THE GENERAL RANGE
OF PREDICTED AFTERNOON MAX TEMPERATURES. THUS CONVECTION MAY HOLD
OFF UNTIL LATE AFTERNOON BEFORE DEVELOPING.              ..08..

UPDATE ISSUED AT 454 AM CDT SAT JUN 15 2013

A FAIRLY SUBSTANTIAL UPDATE TO THE FCST HAS BEEN DONE TO REFLECT
CURRENT TRENDS.

THE MCS OVER THE AREA IS RAPIDLY DECAYING AS IT MOVES AWAY FROM
THE BETTER SUPPORT AND MOISTURE.

MESOANALYSIS HAS A WAKE LOW NEARING KOTM WITH A MESOHIGH IN WEST
CENTRAL ILLINOIS JUST EAST OF THE MISSISSIPPI. OUTFLOW BOUNDARIES
ARE ACROSS CENTRAL ILLINOIS AND INTO CENTRAL MISSOURI.

WATER VAPOR SHOWS THE RESPECTABLE MCV AND ASSOCIATED SHORTWAVE
MOVED ROUGHLY OVER KDSM AND RAP TRENDS HAVE IT REACHING THE
MISSISSIPPI BY MID MORNING. THUS THE MCS WILL CONTINUE TO DECAY BUT
OVERALL LIFT FROM THE MCV WILL HELP GENERATE ISOLATED TO SCATTERED
CONVECTION FOR THE NEXT SEVERAL HOURS.

BUILDING HEIGHTS FROM MID MORNING THROUGH MID DAY SHOULD THEN
RESULT IN A LULL IN THE PRECIPITATION WITH MAINLY DRY CONDITIONS
EXPECTED.

THE NEXT ROUND OF ORGANIZED CONVECTION WILL DEVELOP WITH THE NEXT
SHORTWAVE THAT IS ENTERING THE WESTERN PARTS OF NE/KS. THIS
SHORTWAVE IS EXPECTED TO INITIATE CONVECTION FROM EASTERN NEBRASKA
INTO WESTERN IOWA FROM MID DAY TO EARLY AFTERNOON. AS THIS
CONVECTION ORGANIZES DURING THE AFTERNOON IT WILL EVOLVE INTO THE
NEXT MCS THAT WILL AFFECT THE AREA LATE THIS AFTERNOON AND
TONIGHT.                         ..08..

&&

.SYNOPSIS...
ISSUED AT 315 AM CDT SAT JUN 15 2013

06Z SFC ANALYSIS HAS A SYNOPTIC LOW IN NORTHEAST NEBRASKA WITH A
WARM FRONT RUNNING INTO MISSOURI AND A COLD FRONT INTO SOUTHWEST
NEBRASKA. MESO LOWS AND HIGHS WERE ACROSS IOWA AND NEBRASKA
ASSOCIATED WITH THUNDERSTORM COMPLEXES. DEW POINTS WERE MAINLY IN
THE 50S AND 60S ACROSS THE MIDWEST WITH A NARROW TONGUE OF 70 DEW
POINTS FROM THE SOUTHERN PLAINS INTO EASTERN KANSAS. SATELLITE/RADAR
TRENDS HAVE AN MCS ACROSS IOWA THAT IS SLOWLY DECAYING WITH TIME.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 315 AM CDT SAT JUN 15 2013

NOWCASTING TOOLS HAVE BEEN USED FOR THE IMMEDIATE WX. THESE INDICATE
THE MCS WILL CONTINUE TO DECAY THROUGH SUNRISE WITH DISSIPATION
OCCURRING DURING THE MORNING HOURS.

MCS AND LIFT TOOLS THEN SUGGEST A PERIOD OF DRY WX WITH CLEARING
SKIES FROM MID TO LATE MORNING THROUGH EARLY AFTERNOON. THE NEXT
SHORTWAVE SHOULD INITIATE CONVECTION BY MID DAY OR EARLY AFTERNOON
ACROSS WESTERN IOWA THAT WILL EVOLVE INTO ANOTHER MCS BY EVENING
ACROSS CENTRAL AND EASTERN IOWA. STRONG DIURNAL HEATING AHEAD OF
THIS NEW COMPLEX SHOULD RESULT IN ISOLATED TO SCATTERED STORMS OVER
THE CWFA FROM MID AFTERNOON INTO EARLY EVENING.

SEVERE STORMS MAY BE POSSIBLE THIS AFTERNOON AND EVENING. HOWEVER...
HOW THE CURRENT MCS DECAYS AND HOW MUCH HEATING OCCURS DURING THE
DAY WILL DICTATE THE OVERALL SEVERE THREAT. THE RAP MODEL IS
SUGGESTING POSSIBLY TWO DIFFERENT BOUNDARIES ACROSS THE CWFA DURING
THE AFTERNOON THAT WOULD PROVIDE A FOCUS FOR NEW CONVECTION. ONE
BOUNDARY...THE NORTHERN ONE...APPEARS TO BE LAKE INDUCED. THE
SOUTHERN BOUNDARY LOOKS TO BE THE OUTFLOW BOUNDARY FROM THE CURRENT
MCS MOVING BACK NORTH AS A WARM FRONT.

THUNDERSTORMS SHOULD BE SEEN DURING THE EVENING HOURS ACROSS THE
AREA AS THE NEXT MCS MOVES THROUGH THE AREA. CONVECTION SHOULD BE IN
A WANING/DISSIPATING STAGE AFTER MIDNIGHT AS THE NEXT FRONT/BOUNDARY
BEGINS MOVING INTO THE CWFA.             ..08..

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 315 AM CDT SAT JUN 15 2013

NW FLOW ALOFT AND SURFACE HIGH PRESSURE TO PROVIDE A BREAK IN THE
ACTIVE WEATHER PATTERN FROM MONDAY NIGHT THROUGH WED...THEN RAIN AND
THUNDERSTORM CHANCES RESUME LATE IN THE WEEK.

BEFORE THIS...SUNDAY IS NOW LOOKING LIKE IT WILL BE DRY AS THE
AREA WILL BE UNDER SHORTWAVE SUBSIDENCE AND ALL MODELS HAVE THE MAIN
FRONT SUPPRESSED WELL TO THE SOUTH ACROSS NORTHERN MO INTO CENTRAL
IL AND HIGH PRESSURE BUILDING OVERHEAD. HAVE THUS LIMITED POPS TO
SLIGHT CHANCES ONLY ACROSS THE FAR SOUTH. UNDER MOSTLY SUNNY
SKIES...HIGHS SHOULD BE CLOSE TO GUIDANCE IN THE LOWER TO MID 80S.
SUNDAY NIGHT...WEAK ELEVATED THETAE ADVECTION MAY TRIGGER SHOWERS
AND THUNDERSTORMS AND HAVE LOW CHANCES OVER ESPECIALLY THE SOUTH AND
WEST. THESE CHANCES INCREASE MONDAY WITH LIFT ALONG AND AHEAD OF A
SHORTWAVE AND ASSOCIATED LATE DAY COLD FRONTAL PASSAGE. HIGHS SHOULD
AGAIN REACH INTO THE LOWER TO MID 80S.

SURFACE HIGH PRESSURE AND A CANADIAN AIRMASS WILL THEN DRY WEATHER
WITH LOW HUMIDITY AND SOMEWHAT BELOW NORMAL TEMPERATURES FOR TUE AND
WED. ONE CAVEAT WILL BE A SHORTWAVE PASSAGE ON TUESDAY. THE 00Z
ECMWF IS STRONGER WITH THIS FEATURE THAN OTHER MODELS AND HAS
PRECIPITATION BREAKING OUT DURING THE DAY. WILL KEEP A DRY FORECAST
FOR NOW AND WATCH TO SEE IF THIS IS A NEW TREND OR A LIMITED TO JUST
THIS RUN.

HIGH PRESSURE PUSHES EAST THU AND FRI WITH A MORE ACTIVE TRAIN OF
SHORTWAVES PUSHING THROUGH THE UPPER RIDGE THAT WILL BEGIN TO
ADVANCE INTO THE CENTRAL U.S. TO BRING BACK CHANCES FOR
THUNDERSTORMS. RISING HEIGHTS AND WARM ADVECTION SHOULD RETURN
TEMPERATURES TO LATE JUNE NORMALS WITH HIGHS IN THE 80S AND LOWS IN
THE 60S.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1225 PM CDT SAT JUN 15 2013

GENERALLY VFR CONDITIONS TO DOMINATE TERMINALS EXCEPT IN STRONGEST
THUNDERSTORMS NEXT 12 HOURS AND RISK OF PATCHY FOG TOWARD SUNRISE.
WEAK UPPER LEVEL DISTURBANCES WILL PRODUCE AREAS OF THUNDERSTORMS
AND SHOWERS AT ALL TERMINALS THROUGH 16/09Z. SCT-BKN CLOUDS WITH
BASES AOA 4K AGL WILL BRIEFLY LOWER TO 2-3K AGL IN STRONGEST STORMS.
BRIEF HEAVY RAINS MAY ALSO LOWER VISIBILITIES TO 1-3 MILES.
CONVECTION SHOULD SLIDE EAST BEFORE DAYBREAK WITH PATCHY FOG
POSSIBLE WITH VISIBILITIES LOCALLY REDUCED TO 2-5 MILES. ANY FOG
TO BURN OFF BY 16/14Z WITH MOSTLY SUNNY SKIES ON SUNDAY.

NICHOLS

&&

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

&&

$$

UPDATE...08
SYNOPSIS...08
SHORT TERM...08
LONG TERM...SHEETS
AVIATION...NICHOLS