000
FXUS63 KDVN 161200
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
700 AM CDT THU MAY 16 2013

.UPDATE...
ISSUED AT 700 AM CDT THU MAY 16 2013
HAVE UPDATED FOR THE CURRENT STATUS OF THE BAND OF RAIN WITH
EMBEDDED THUNDER ACROSS THE SOUTHERN COUNTIES OF THE CWA. NOW THAT
IT HAS STRATIFIED...I EXPECT IT TO GRADUALLY DIMINISH OVER THE
NEXT SEVERAL HOURS. THUS...HAVE ALLOWED POPS TO DIMINISH DURING
THE MORNING. HAVE ALSO TAKEN ANOTHER LOOK AT TONIGHT...AND THE
DYNAMICS FOR THIS EVENING ARE LOOKING MORE AND MORE FOCUSED OUT
OVER THE PLAINS...WITH LITTLE IF ANY CONVERGENCE ALONG THE RATHER
WEAK BOUNDARY STILL DRAPED ACROSS THE FORECAST AREA DURING THE
EVENING AND OVERNIGHT PERIOD. HAVE REDUCED THE POPS DURING THIS
TIME RANGE. LE

&&

.SYNOPSIS...
ISSUED AT 330 AM CDT THU MAY 16 2013

A STATIONARY FRONT IS DRAPED ALONG THE KANSAS/NEBRASKA
BORDER...ACROSS FAR NORTHERN MISSOURI...AND CONTINUING EAST ACROSS
CENTRAL ILLINOIS AND INDIANA.  THIS FRONT SERVED AS THE FOCUS FOR
SURFACE BASED CONVECTION LAST EVENING.  AT 850MB THE FRONT SURFACE
IS JUST A LITTLE WAYS NORTH OF THE SURFACE BOUNDARY...AND IS BEING
NICELY DEPICTED BY THE CONVECTION OVER SOUTHERN IOWA..AND ALSO
CONTINUING EAST INTO ILLINOIS AND INDIANA.  FROM THE 00Z UPPER AIR
ANALYSIS IT ALSO CONTINUES WEST TO NORTHEAST COLORADO...GENERALLY
NEAR OR JUST NORTH OF THE SURFACE BOUNDARY.  THE 850MB ANALYSIS ALSO
SHOWS PLENTY OF LOW LEVEL MOISTURE BEING ADVECTED NORTH AND
IMPINGING ON THE 850MB BOUNDARY...BUT NOT VERY STRONGLY AND IS ONLY
JUST ENOUGH TO PRODUCE THE SHOWERS AND THUNDERSTORMS WE HAVE ON THE
RADAR NOW.   LE

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 330 AM CDT THU MAY 16 2013

THE MAIN CONCERN THE NEXT 24 HOURS IS WHERE AND WHEN THE SHOWERS AND
THUNDERSTORMS WILL FORM.

TODAY...EXPECT THAT THIS CURRENT BAND OF CONVECTION IS GOING TO
GRADUALLY WEAKEN TOWARDS SUNRISE...THOUGH IT MAY FLARE A LITTLE
PERIODICALLY.  THEN...EXPECT SOME ISOLATED TO SCATTERED ACTIVITY
ALONG THE BOUNDARY DURING THE MORNING AND EARLY AFTERNOON AS STORMS
SETTLE DOWN AND THEN REFOCUS UPON THE SURFACE BOUNDARY DURING THE
AFTERNOON.  HOWEVER...BY THEN IT WILL BE SLOWLY PUSHING NORTH IN
RESPONSE TO A SHORTWAVE MOVING ACROSS THE PLAINS...AND NEW
CONVECTION FIRING OUT OVER NEBRASKA AND SOUTH DAKOTA THIS AFTERNOON.
SOME MODELS ARE HINTING THAT WE WILL HAVE LITTLE/NO CONVECTION OVER
THE AREA THIS AFTERNOON...BUT CANNOT RULE OUT SOME ISOLATED TO
SCATTERED ACTIVITY AS LOW LEVEL CAPES SHOULD APPROACH 1000-1500 SOUTH
OF THE FRONT AND WEAK LOW LEVEL CONVERGENCE ALONG IT SHOULD SERVE AS
A FOCUS.  DO NOT EXPECT ANY SEVERE STORMS OUT OF THIS...BUT SLOW
MOVING GARDEN VARIETY SHOWERS AND THUNDERSTORMS. HIGH TEMPERATURES
TODAY SHOULD BE FAIRLY CLOSE TO WHAT WE HAD YESTERDAY...IF SLIGHTLY
COOLER SOUTH WHERE MORE CLOUD COVER IS EXPECTED.

TONIGHT EXPECT THAT THE FRONT WILL CONTINUE TO SLOWLY PULL NORTH AS
THE CONVECTION OUT WEST FORMS INTO AN MCS OVER EASTERN SOUTH DAKOTA
AND NORTHEAST NEBRASKA AS WELL.  HAVE KEPT THE SLIGHT CHANCE POPS
GOING OVER THE CWA AS THE FRONT PULLS NORTH..BUT CONFIDENCE IS NOT
VERY HIGH.  IN FACT...THERE IS SOME RISK THAT THE MCS WILL MOVE EAST
AND BEGIN TO MOVE INTO THE FORECAST AREA BY 12Z...ESPECIALLY IF IT
CAN CAUSE SOME ACTIVITY TO ZIPPER ALONG THE FRONT TOWARDS US.
THUS...THE EVENING POPS ARE FAIRLY LOW...BUT HAVE RAMPED POPS UP TO
CHANCE CATEGORY AFTER MIDNIGHT.   MIN TEMPS IN THE 50S AND LOW 60S
CAN BE EXPECTED. HAVE COOLED OFF THE NORTHEAST AS WE MAY GET SOME
LAKE EFFECTS IN THERE AS THE WINDS TURN MORE NORTHEAST.    LE

.LONG TERM...(FRIDAY THROUGH NEXT WEDNESDAY)
ISSUED AT 330 AM CDT THU MAY 16 2013

FRIDAY AND SATURDAY...WILL CONTINUE TO KEEP CHC POPS FOR SHOWERS AND
THUNDERSTORMS ACRS THE CWA ON FRI WITH HIGHEST CHC AXIS ORIENTED
FROM NW-TO-SE ACRS FCST AREA. THIS IN AREA OF WARM AIR ADVECTION
WING ASSOCIATED WITH PROBABLY MCS MOVING ACRS FAR NORTHERN IA...MN
AND INTO WI. STILL A CHANCE FOR THE SOUTHEAST FLANK OF THE MAIN
SYSTEM ITSELF TO GRAZE TH AFR NORTHERN CWA FRI MORNING. ACTIVITY
SHOULD DIURNALLY WANE FRI AFTERNOON. SOME MODERATE AMOUNTS OF
RAINFALL POSSIBLE IN THE FAR NORTHERN CWA OR UNDER WAA WING AXIS.
LULLS OR BREAKS IN THE PRECIP TO ALLOW TEMPS TO WARM TO AROUND 80
BUT THEY MAY STAY COOLER IN THE 70S ACRS THE FAR NORTH IN LINGERING
CONVECTIVE ZONE AND CLOUD DEBRIS...EAST BOUNDARY LAYER FLOW AS WELL
NORTH OF LINGERING LLVL BOUNDARY. LATEST SUITE OF 00Z MODEL RUNS
AND ENSEMBLES CONTINUE TO TREND IN HANDLING OF L/W UPPER TROF
ESTABLISHING ACRS THE ROCKIES EFFECTIVELY ENHANCING UPPER RIDGING TO
TH EAST OF IT ACRS MUCH OF THE MID AND UPPER MS RVR VALLEY REGIONS
THROUGH SAT. THUS AFTER A CHANCE OF LINGERING SHOWERS/STORMS EARLY
FRI EVENING...THE DVN CWA MAY BE MAINLY DRY THROUGH 12Z SUNDAY.
FCST SOUNDINGS SUGGESTING BUILDING CAPPING WARM WEDGE ALOFT ON SAT
WILL ALSO HAMPER AMBIENT HEATING INDUCED THUNDERSTORMS. LLVL MOISTURE
FEED/WARM CONVEYOR UP TO THE LEE OF SHEARING L/W TROF SUGGESTS THE
SIGNIFICANT CONVECTION TO OCCUR ACRS MAINLY THE CENTRAL INTO
NORTHERN PLAINS DURING THE SECOND HALF OF THIS PERIOD. WITH LACK OF
PRECIP..SAT HIGHS WIDESPREAD IN THE 80-85 DEGREE RANGE EXCEPT ALONG
AND NORTH OF THE HWY 20 CORRIDOR.

SUNDAY AND MONDAY...ASSESSING THE LATEST RUNS...INCREASING NEG
TILTED UPPER TROF AND DEEPENING LLVL CYCLONE SOMEWHERE OVER THE
NORTHEASTERN PLAINS OR WESTERN MN THIS PERIOD STILL SUGGESTS A
POTENTIALLY SIGNIFICANT CONVECTIVE EVENT OR TWO MAY OCCUR IN OR
NEAR THE DVN CWA THIS PERIOD. BEST GUESS AT THIS POINT SUGGESTS MUCH
OF THE DAY SUNDAY TO BE DRY AND HEAT UP INTO THE MID TO UPPER 80S
WITH SFC DPTS MAKING IT INTO THE 60S FOR DECENT CAPE VALUES.
AFTERNOON CONVECTION MAY STILL LOOK TO TAKE OFF ACRS WESTERN INTO
CENTRAL IA...THEN LOOK TO PROPAGATE INTO THE DVN CWA SUNDAY NIGHT.
STRONG TO SVR CONVECTION POSSIBLE AS IT ARRIVES...AS WELL AS
LOCALLY HEAVY RAINFALL POSSIBLE OF OVER AN INCH BY MONDAY MORNING.
MONDAY STILL APPEARS A QUESTION MARK VERY MUCH DEPENDING ON WHAT
OCCURS OR LINGERS OUT OF SUNDAY NIGHT. CONVECTIVE DEBRIS AND OUTFLOW
LASTING LONG ENOUGH TO LIMIT INSTABILITY LOCALLY AND SHIFTING
STORM INITIATION JUST OFF TO THE EAST AND SOUTH...OR THE MORNING
DEBRIS CLEARS OFF IN TIME FOR RAPID DESTABILIZATION. THIS WOULD BE
TROUBLE AS SYNOPTICALLY STRONGEST FORCING OF THE PERIOD AND POSSIBLE
SUPERCELL/TORNADIC SET-UP WOULD LOOK TO TAKE PLACE AHEAD OF INCOMING
DRY SLOT ACRS AT LEAST THE EASTERN OF SOUTHEASTERN HALF OF THE DVN
CWA BY MONDAY AFTERNOON AND EVENING. HIGH CHC POPS OR EVEN SOME
LIKELY/S TO CONTINUE FROM SUNDAY NIGHT THROUGH MON...ALTHOUGH PLENTY
OF QUESTIONS CONTINUE BUT THE SIGNALS HAVE BEEN THERE FOR A FEW DAYS
NOW. DRY SLOT ASSOCIATED WITH A STRONG WRAPPED UP SYSTEM MAY BRING
LULL IN THE ACTIVITY LATE MON NIGHT INTO TUE.

TUESDAY AND WEDNESDAY...CLOSED OFF UPPER LOW BEING HANDLED
DIFFERENTLY BY SEVERAL OF THE MEDIUM RANGE MODELS THIS PERIOD...BUT
LONG RANGE SIGNALS SUGGEST IT TO BE BLOCKED OR GYRATE SLOWLY TOWARD
THE MID/UPPER MS RVR VALLEY THROUGH THE END OF THE LONG RANGE FOR
MORE SHOWERS AS IT BECOMES COOL CORE AND INDUCING UNSTABLE PARCELS.
HOW COOL CORE THE CLOSED LOW BECOMES AND WHERE IS VERY MUCH UP TO
DEBATE BETWEEN THE THE VARIOUS SOLUTIONS.    ..12..

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 700 AM CDT THU MAY 16 2013

A WEAK STATIONARY FRONT DRAPED ACROSS SOUTHERN IOWA WILL CONTINUE
TO SERVE AS A FOCUS FOR SHOWERS AND THUNDERSTORMS FOR SEVERAL MORE
HOURS THIS MORNING. THE BAND CURRENTLY IN PLACE HAS
STRATIFIED...SO HAVE A PERIOD OF RAIN WITH EMBEDDED THUNDER
UNTIL 17Z THIS MORNING FOR KBRL. KCID...KMLI AND KDBQ TO REMAIN
DRY. VFR CONDITIONS TO CONTINUE FOR ALL TERMINALS THROUGH THE
PERIOD. LIGHT WINDS AT OR LESS THAN 10KTS OUT OF THE EAST OR
SOUTHEAST. TONIGHT SHOWERS AND THUNDERSTORMS MAY MOVE TOWARDS THE
TERMINALS SOMETIME AFTER 09Z...BUT WITH UNCERTAINTY IN TIMING AND
LOCATION HAVE LEFT OUT OF TERMINALS FOR NOW.     LE

&&

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

$$

UPDATE...LE
SYNOPSIS...LE
SHORT TERM...LE
LONG TERM...12
AVIATION...LE