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000
FXUS63 KDVN 151803
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
103 PM CDT WED MAY 15 2013

.UPDATE...
ISSUED AT 645 AM CDT WED MAY 15 2013

HAVE JUST SENT OUT A QUICK UPDATE TO FRESHEN UP TEMPERATURE AND
CLOUD TRENDS.   SEE UPDATED AVIATION SECTION BELOW.

&&

.SYNOPSIS...
ISSUED AT 330 AM CDT WED MAY 15 2013

A COLD FRONT IS SLOWLY SAGGING SOUTH ACROSS THE AREA THIS MORNING.
AS OF 3 AM IT WAS DRAPED FROM SOUTH OF DUBUQUE TO NEAR CEDAR
RAPIDS...AND THEN EXTENDING WEST TO BETWEEN TAMA AND PELLA IOWA.
NORTH OF THE FRONT TEMPERATURES FELL INTO THE 60S...WITH MID 70S TO
THE SOUTH.  WE HAVE HAD SOME ISOLATED SHOWERS POP UP ALONG AND AHEAD
OF THE BOUNDARY FOR THE LAST SEVERAL HOURS...BUT ALL WEAK AND WITH
REFLECTIVITIES GENERALLY BELOW 40DBZ.  AT UPPER LEVELS...THE 00Z
ANALYSIS SHOWED THAT WE WERE +24C AT 850MB...A CONTRIBUTOR TO OUR
NEAR RECORD HEAT OF YESTERDAY.  IT ALSO SHOWS A STRONG COLD FRONT
MOVING TOWARDS THE AREA...GENERALLY DRAPED FROM NORTHERN WISCONSIN
SOUTHWEST TO EASTERN COLORADO.  A WARM FRONT DRAPED EAST FROM IT
ACROSS WISCONSIN AND SOUTHEAST INTO OHIO.  IN THE WARM SECTOR...WE
HAD DEEP SOUTHERLY FLOW OF 35-40KTS WITH TEMPERATURES WELL INTO THE
+20C RANGE FROM HERE BACK INTO KANSAS AND NORTHWEST TEXAS.  A PLUME
OF +10C DEWPOINTS WAS POOLED OVER SOUTHERN TEXAS...WHICH WAS
BEGINNING TO STREAM NORTH IN THAT STRONG SOUTHERLY FLOW.  THIS WILL
HAVE INTERESTING CONSEQUENCES FOR THE BOUNDARY TONIGHT.   LE

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 330 AM CDT WED MAY 15 2013

MAIN CONCERNS THIS MORNING INCLUDE THE THUNDERSTORM POTENTIAL FOR
TONIGHT...AND HIGH TEMPERATURES TODAY.

TODAY THE SURFACE COLD FRONT WILL CONTINUE TO SAG SOUTH ACROSS THE
AREA AND IS EXPECTED TO SLOW DOWN AND SHOULD STALL JUST SOUTH OF THE
AREA OVER NORTHERN MISSOURI BY MID AFTERNOON.  AS THIS BOUNDARY
MOVES SOUTH EXPECT THAT THE ISOLATED TO SCATTERED SHOWERS SHOULD
CONTINUE TO FORM ALONG IT...AND HAVE MAINTAINED SOME SLIGHT POPS
ALONG IT AS THE FRONT MOVES SOUTH.  HOWEVER...THAT WILL MAINTAIN
SOME CLOUD COVER OVER THE AREA MOST OF THE MORNING AND EARLY
AFTERNOON.  A TRAJECTORY ANALYSIS FOR TOMORROW AFTERNOON SHOWS THE
SOURCE AIRMASS FOR OUR AREA TO BE IN SOUTHERN CANADA JUST WEST OF
LAKE WINNIPEG.  YESTERDAY THESE AREAS GOT INTO THE MIDDLE TO UPPER
70S FOR HIGHS.  HOWEVER...WE WILL HAVE BEEN UNDERGOING SUBSIDENCE
AND DRYING AS THIS AIRMASS MOVES IN...OUR SUNSHINE IS STRONGER AND
OUR GROUND IS PROBABLY WARMER.  THUS...FEEL FAIRLY CONFIDENT IN THE
GUIDANCE VALUES IN THE UPPER 70S NORTH TO MID 80S SOUTH.

TONIGHT THAT PLUME OF MOISTURE OVER TEXAS FROM LAST NIGHT SHOULD
BEGIN IMPACTING UPON OUR BOUNDARY...AS IT IS DRAPED ACROSS THE
IOWA/MISSOURI BORDER AREA.  BY MID EVENING I EXPECT SOME SCATTERED
STORM ACTIVITY WHICH SHOULD INCREASE OVER THE NEXT FEW HOURS AND
CONTINUE MOST OF THE NIGHT.  STORMS ON THE SOUTHERN FLANKS OF THIS
SHOULD HAVE ACCESS TO A SIGNIFICANT POOL OF CAPE AND DECENT
SHEAR...SO AM NOT TOO SURPRISED TO SEE THE SEE TEXT OVER NORTHERN
MISSOURI ON THE SPC DAY 1 OUTLOOK.  HOWEVER...FARTHER NORTH THERE IS
LESS POTENTIAL FOR STRONGER STORMS AND WE CAN EXPECT SOME DECENT
RAINS WITH THE STORMS WE DO GET.  HAVE CHANCE TO LOW END LIKELY POPS
GOING FOR AREAS SOUTH OF INTERSTATE 80 OVERNIGHT...WITH DRY
CONDITIONS TO THE NORTH.  MIN TEMPS SHOULD BE ABLE TO FALL INTO THE
MID 50S TO LOW 60S.

LE

.LONG TERM...(THURSDAY THROUGH NEXT TUESDAY)
ISSUED AT 330 AM CDT WED MAY 15 2013

THURSDAY...MOST OF THE 00Z RUN MODELS GENERALLY AGREE ON BROAD UPPER
RIDGING TO ESTABLISH ACRS THE NORTHERN PLAINS INTO THE GRT LKS WITH
THE POTENTIAL OF AN UNDERCUTTING VORT MAX ROLLING ACRS THE REGION
THIS PERIOD. LLVL BACKDOOR TYPE HIGH TO PUSH DOWN THE WESTERN LKS
AS WELL THU INTO THU NIGHT. MAIN SFC FRONT WILL LOOK TO BE QUASI-
STATIONARY FROM SOUTHERN NEB INTO SOUTH CENTRAL IL. WILL HAVE TO
ACCOUNT FOR FESTERING SHOWERS AND STORMS LINGERING OUT OF WED NIGHT
INTO THU MORNING ACRS THE SOUTHERN THIRD OF THE CWA...THEN A MIDDAY
LULL OR DECREASE BEFORE AFTERNOON CONVERGENCE/SQUEEZE BETWEEN GRT
LKS HIGH AND PLAINS LLVL RETURN FLOW MAY FOSTER SOME RENEWED
CONVECTION ALONG AND NORTH OF THE FRONT. HIGH TEMPS WARMER NORTH
OF I80 WHERE BETTER CHANCE OF SOME INSOLATION AND DEEPER MIXING. THU
NIGHT MCS TOOLS SUGGEST BETTER SUPPORT FOR SUCH A FEATURE FROM ACRS
NEB/SD INTO NW IA AND SOUTHWESTERN MN. BUT INCREASING ELEVATED THTA-
E ADVECTION AND CONVERGENT WING SHOULD ALLOW FOR ASSOCIATED BAND OF
ELEVATED SHOWERS AND STORMS TO TAKE SHAPE ACRS THE CENTRAL INTO
NORTHWESTERN CWA LATER THU NIGHT INTO EARLY FRI MORNING AND TRY TO
CONNECT TO THE MAIN MCS ACRS NORTHERN IA INTO SOUTHERN MN UNDER
UPPER JET DIVERGENT MAX. WILL PLACE POPS ACCORDINGLY. A FEW AREAS
MAY GET FROM A QUARTER TO A HALF INCH OF RAIN BY FRI MORNING. THE
GFS CONTINUES TO BE THE MOST SATURATED AND BULLISH ON CONVECTIVE
BREAK OUT THIS PERIOD AND WILL LEAN TOWARD THE ECMWF PLACEMENT...BUT
THE EURO MAY BE A BIT TOO DRY WITH IT/S QPF.

FRIDAY AND SATURDAY...AGAIN WILL HAVE TO ACCOUNT FOR SOME
MORNING CONVECTION LINGERING OUT OF THU NIGHT ESPECIALLY ACRS
THE NORTH OR EVEN ACCOUNT FOR A PORTION OF THE UPSTREAM MCS IN
NORTH CENTRAL IA/SOUTHERN MN TO TRY AND MAKE IT INTO NORTHERN
PORTIONS OF THE CWA...BUT SHOULD BE DIURNALLY WEAKENING. TEMPS
MY BE TRICKY ON FRI WITH OUTFLOW BOUNDARIES...CONVECTIVE DEBRIS
AND ONGOING SFC FRONT BEING HELD AT BAY BY WESTERN GRT LKS
RIDGING. THE NEW 00Z RUNS CONTINUE TO BUILD ON THE IDEA OF THE
UPPER RIDGE GETTING SQUEEZED/AMPLIFIED UP ACRS THE MID AND UPPER MS
RVR VALLEY REGIONS AS WEST COAST L/W TROF MIGRATES EASTWARD TO AND
OVER THE ROCKIES THROUGH THE PERIOD. FRI NIGHT MAY BE TOTALLY DRY
BUT WILL KNOCK DOWN POPS TO SLIGHT CHC FOR NOW. UPPER RIDGING WILL
LOOK TO REALLY TAKE HOLD ACRS THE WESTERN GRT LKS/MID-UPPER MS RVR
VALLEYS ON SAT WITH MUCH OF THE DAY POSSIBLY DRY LOCALLY AS WELL...
WHILE WIDESPREAD CONVECTION BREAKS LOOSE ACRS THE CENTRAL INTO
NORTHERN PLAINS IN LEE-SIDE BULLSEYE OF ROCKIES UPPER TROF COMPLEX.
WITH LACK OF PRECIP AND LESS CLOUDS...COULD BE WIDESPREAD LOWER 80S
FOR SAT HIGHS. A LOW CHANCE FOR UPSTREAM CONVECTIVE COMPLEX TO MAKE
IT THIS FAR EAST BY SUNDAY MORNING.

SUNDAY THROUGH TUESDAY...STILL APPEARS THAT A POTENTIALLY STRONG TO
SVR STORM EPISODE SOMEWHERE IN THIS WINDOW AS THE MAIN UPPER TROF
LIFTS OUT OF THE SOUTHERN AND CENTRAL PLAINS AND TRIES TO BECOME NEG
TILTED. MUCH WILL DEPEND ON UPPER LEVEL JET ENERGY PLACEMENT
ASSOCIATED WITH THIS PROCESS...AS WELL AS BUILDING
THERMODYNAMICS/HEATING TO DRIVE THE NECESSARY INSTABILITY. THE NEW
ECMWF AND THE 00Z GFS DEVELOP STRONG STORMS ACRS WESTERN INTO CENTRAL
IA SUNDAY AFTERNOON AND EARLY EVENING...WITH THEM THEN PROPAGATING
ACRS THE DVN CWA LATER SUNDAY NIGHT IN A FORM OF AN MCS. THE GFS
SOMEWHAT SLOWER AND FURTHER WEST THAN THE ECMWF. A MAINLY DRY SUNDAY
BEFORE STORMS ARRIVE LATER SUNDAY NIGHT STILL SUGGESTS HIGHS
IN THE UPPER 80S. SFC DPTS MAY CLIMB INTO THE 60S. IF WE GET THE HIGH
ENOUGH/MID 60 DEWPOINTS...THE AIRMASS WILL SUPPORT STRONG TO SVR
STORMS IN THE LOCAL AREA AS WELL SUNDAY EVENING. MONDAY LOOKING MORE
MUDDLED AND MUCH DEPENDS ON WHAT OCCURS OR LINGERS OUT OF SUNDAY
NIGHT. CONVECTIVE DEBRIS AN OUTFLOW KILLING INSTABILITY...OR DEBRIS
CLEAR OFF IN TIME FOR DESTABILIZATION AS STRONGEST FORCING OF THE
ENTIRE LONG RANGE FCST SHIFTS UP ALONG AND SOUTH/EAST OF THE DVN
CWA AS UPPER LOW CLOSES OFF AND DEEPENS ACRS SOUTHERN INTO CENTRAL
MN. AFTERNOON STORMS COULD FIRE OVERHEAD OR JUST EAST/SOUTHEAST OF
THE DVN CWA. HIGH CHC POPS OR EVEN SOME LIKELY/S TO CONTINUE FROM SUN
THROUGH MON. DRY SLOT ASSOCIATED WITH A STRONG WRAPPED UP SYSTEM
MAY BRING LULL IN THE ACTIVITY MON NIGHT INTO TUE...BEFORE THE UPPER
LOW WILL HAVE TO EVENTUALLY BE DEALT WITH AS IT SLOW ROLLS OR EVEN
GETS BLOCKED ACRS THE UPPER MS RVR VALLEY LATE TUE INTO WED.
  ..12..

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1256 PM CDT WED MAY 15 2013

PREDOMINANTLY VFR CONDITIONS EXPECTED THROUGH THURSDAY MORNING.
A WEAK COLD FRONT CONTINUES TO SAG SOUTH NEAR THE IOWA/MISSOURI
BORDER...HAVING RECENTLY PASSED TO THE SOUTH OF KBRL. THE FRONT IS
EXPECTED TO PUSH SOUTHWARD ONLY SLIGHTLY...BEFORE SHIFTING
NORTHWARD AGAIN TOMORROW. A COUPLE BANDS OF SCATTERED SHOWERS HAVE
DEVELOPED IN THE VICINITY OF THE FRONT TODAY. SCATTERED SHOWER
ACTIVITY IS EXPECTED TO CONTINUE THROUGH TOMORROW...WITH THE BEST
CHANCES ACROSS SOUTHEAST IOWA AND WEST CENTRAL ILLINOIS. ISOLATED
THUNDERSTORMS ARE ALSO POSSIBLE. KEPT WITH VCSH FOR KBRL SINCE
CONFIDENCE FOR STORMS AT ANY INDIVIDUAL LOCATION IS LOW. WINDS
BEHIND THE FRONT ARE GENERALLY FROM THE NORTH AND ARE EXPECTED TO
BE AROUND 10KTS THROUGH THE AFTERNOON...AND DECREASE LATER THIS
EVENING.

STOFLET

&&

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

$$

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