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000
FXUS63 KDVN 150816
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
316 AM CDT SAT JUN 15 2013

.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 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1135 PM CDT FRI JUN 14 2013

TIMING OF PRECIPITATION THE MAIN CHALLENGE WITH 06Z TAFS. BOWING
LINE OF STORMS CURRENTLY OVER SOUTH CENTRAL INTO SOUTHWEST
IOWA WILL LIKELY INTERRUPT LOW LEVEL JET INTO EASTERN IOWA FOR AS
LONG AS THE LINE CONTINUES. FAIRLY LARGE STRATIFORM RAIN SHIELD
WITH EMBEDDED STORMS OVER CENTRAL INTO NORTHERN IOWA MOVING
EASTWARD WITH AN APPARENT CONVECTIVELY ENHANCED SHORTWAVE.
THUS... DESPITE INTERRUPT OF LOW LEVEL JET... SUFFICIENT FORCING
FROM AFOREMENTIONED WAVE SHOULD ALLOW FOR INCREASE IN RAIN WITH
SOME STORMS OVERNIGHT. IF SOUTHERN IOWA LINE WEAKENS ALLOWING
LOW LEVEL JET TO IMPINGE ON EASTERN IOWA THEN STRONG CONVERGENCE
AND MOISTURE TRANSPORT COULD LEAD TO INTENSIFICATION OF CONVECTION
OVER AREA LATER TONIGHT UNTIL MID MORNING SATURDAY...WITH LOCALLY
HEAVY RAINS. ANTICIPATE A BREAK OR RELATIVE LULL IN PRECIPITATION
BY MIDDAY WITH ADDITIONAL DEVELOPMENT BY MID AFTERNOON INTO SATURDAY
EVENING AHEAD OF NEXT DISTURBANCE. POTENTIAL EXISTS FOR SOME SEVERE
STORMS. UNCERTAINTY WITH COVERAGE AND LOCATION AND THUS VCTS MENTION
DURING THE AFTERNOON AND EVENING AT ALL SITES. OVERALL... EXPECT
MVFR TO POSSIBLY IFR CONDITIONS ESPECIALLY FOR VSBYS WITH ANY
STORMS OTHERWISE...VFR CONDITIONS TO PREVAIL. WINDS LIKELY TO
FAVOR SOUTHERLY THROUGH SATURDAY EXCEPT VARIABLE IN STORMS. COULD
SEE SOME GUSTS BY AFTERNOON. SATURDAY NIGHT WINDS SHOULD BECOME
LIGHT AND SHIFT TO WESTERLY.


&&

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

$$

SYNOPSIS...08
SHORT TERM...08
LONG TERM...SHEETS
AVIATION...05