Special Weather Statement, NWS Quad Cities, IA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
333 AM CDT FRI JUN 10 2011

.SYNOPSIS...
ONGOING MCS OVER THE AREA THIS MORNING IS THE MAIN WEATHER CONCERN.
THIS MCS HAS BEEN MAKING A SLOW TREK TO THE EAST SINCE EVENING...WITH A
SLIGHT NORTH OF EAST TREND IN THE LAST FEW HOURS.  THE 850MB LOW
LEVEL JET OF 20-30KTS HAS BEEN FEEDING PLENTY OF LOW LEVEL MOISTURE
INTO IN FROM THE SOUTHWEST SIDE...AND THOUGH THERE HAVE BEEN A FEW
ISOLATED SEVERE REPORTS THIS SYSTEM HAS TAMED DOWN SIGNIFICANTLY
SINCE AROUND 11 PM.  THIS MCS HAS BEEN RIDING ALONG AND JUST NORTH
OF A STATIONARY/WARM FRONT BOUNDARY DRAPED FROM A SURFACE LOW OVER
NORTHWEST MISSOURI ACROSS NORTHERN MISSOURI AND INTO CENTRAL
ILLINOIS.  EARLIER RAINS OF 1 TO 1.5 INCHES ACROSS THE I80 CORRIDOR
HAVE LEFT THAT AREA SUSCEPTIBLE TO FLASH FLOODING...SO THESE AREAS
ARE BEING WATCHED CAREFULLY FOR THIS POTENTIAL.  WHILE THE MOISTURE
FEED CONTINUES QUITE STRONG INTO THE AREA...THE INSTABILITY THAT
MADE THIS MCS PRODUCE SEVERE WEATHER IN THE EVENING HOURS HAS
WANED...AND WAS WEAKER TOWARDS OUR DIRECTION ANYHOW.    ..LE..

&&

.SHORT TERM...TODAY AND TONIGHT...
MAIN QUESTION THIS MORNING IS HOW QUICKLY THE MCS AND ASSOCIATED
DEBRIS CLOUDS AND COOL TEMPERATURES WILL RETREAT NORTHEAST OUT OF
THE AREA TODAY. A TIME DISTANCE FEATURE ON THE BACK EDGE OF THE
LAST FRAGMENTS OF CONVECTION BRING LAST OF THE MCS TO ABOUT THE
CENTRAL PORTIONS OF THE CWA AROUND 12Z...BUT NOT OUT OF THE CWA
UNTIL 14-15Z THIS MORNING. MODELS ALSO SEEM TO DEPICT THIS MCS
WEAKENING IN THE NEXT FEW HOURS AS THE FEEDING INSTABILITY
CONTINUES TO WANE AND THE LOW LEVEL JET BEGINS TO WEAKEN AGAIN
THIS MORNING...SO THE END OF THIS MCS MAY HAPPEN EARLIER THAN 15Z.
HOWEVER...WITH THE HEAVIER RAINS ONLY JUST NOW GETTING TO SOME OF
THE MORE VULNERABLE CENTRAL AREAS OF THE CWA...HAVE ELECTED TO
EXTEND THE FLASH FLOOD WATCH UNTIL 15Z. SHOULD THE MCS WANE
EARLIER...THE WATCH CAN ALWAYS BE CANCELED EARLIER.

ONCE THE MCS EXITS THE AREA TO THE NORTHEAST THIS MORNING...EXPECT
THAT WE WILL BEGIN TO REGENERATE INSTABILITY ALONG AND SOUTH OF THE
FRONTAL BOUNDARY WHICH REMAINS DRAPED ACROSS THE CWA. THE SURFACE
LOW SLOWLY MOVES ACROSS THE SOUTHERN HALF OF THE CWA ALONG THE
BOUNDARY...WHICH WILL HAVE BEEN PULLED NORTH A LITTLE BY THE SURFACE
LOW.  THIS MORNINGS POPS BEHIND THE MCS SHOULD STILL BE
COOL...CLOUDY AND WITH SOME LINGERING SHOWERS.  HOWEVER...THE
BUILDING INSTABILITY WILL ALLOW NEW DEVELOPMENT THIS AFTERNOON AND
TONIGHT ALONG THE BOUNDARY.  ANOTHER NIGHT OF LIKELY POPS FOR AT
LEAST A PORTION OF THE CWA...THIS CASE ACROSS THE SOUTH.  TONIGHT
SHOULD BE MAINLY SOUTH...WITH MOST OF THE SEVERE WEATHER POTENTIAL
TO THE SOUTH OF THE CWA.  TODAYS MAX TEMPS TO BE SIMILAR TO
YESTERDAY WITH A SHARP GRADIENT FROM NORTH TO SOUTH...RANGING FROM
THE UPPER 60S TO MID 80S.

TONIGHT THE EVENING CONVECTION SHOULD EVENTUALLY SHIFT EAST...AND
SOME LINGERING SHOWERS AND EMBEDDED THUNDER TO BE THE MAIN FEATURE
OF THE OVERNIGHT...AND MAINLY OVER THE SOUTHERN HALF OF THE CWA.
THIS TO SLOWLY EXIT THE AREA TO THE EAST AFTER MIDNIGHT.  MORE COOL
TEMPS AND NORTH WINDS OVERNIGHT.  ..LE..

.LONG TERM...FRIDAY NIGHT THROUGH THURSDAY...
AFTER A RELATIVELY QUIET SATURDAY...THINGS GET INTERESTING AGAIN BY
LATE SUNDAY THROUGH WEDNESDAY.  THE UPPER LEVEL RIDGE SHIFTS EAST OF
THE FORECAST AREA...ALLOWING SOUTHWEST UPPER LEVEL FLOW TO PUSH
BANDS OF WARM AIR ADVECTION OUR WAY.  THE FIRST COMES IN SUNDAY
AFTERNOON AND NIGHT AS A WEAK SHORTWAVE AND WARM AIR ADVECTION WAVE
COMES OUT OF THE PLAINS IN THE SOUTHWEST FLOW.  THIS SHOULD AFFECT
MAINLY THE SOUTHWEST HALF OF THE AREA.  MONDAY AND MONDAY NIGHT THIS
WARM AIR ADVECTION ZONE PUSHES A LITTLE FARTHER NORTH...AND WE
SHOULD GET A LITTLE BETTER CHANCE FOR SHOWERS AND THUNDERSTORMS
THEN.

TUESDAY AND WEDNESDAY HAVE A FAIRLY SIGNIFICANT CHANCE OF RAIN AS A
STRONGER TROUGH AXIS PUSHES THROUGH THE AREA...TEMPORARILY SHOVING
THE RIDGE AXIS TO THE EAST.  HAVE KEPT POPS TO CHANCE CATEGORY FOR
NOW...BUT IF THIS PATTERN CONTINUES WILL ALLOW POPS TO RISE WITH
THIS FEATURE...ESPECIALLY TUESDAY NIGHT.  MODEL DIFFERENCES WITH THE
STRENGTH OF THE UPPER LEVEL FEATURE ARE ALSO CONTRIBUTING TO SOME
UNCERTAINTY.

THURSDAY THE UPPER LEVEL RIDGING PUSHES BACK INTO THE AREA AND QUIET
WEATHER SHOULD RETURN TO THE FORECAST AREA.
..LE..

&&

.AVIATION...
HIGHER BASED MVFR RAIN WITH EMBEDDED THUNDER WILL CONTINUE AT THE
CID AND DBQ TERMINALS THROUGH 15Z BEFORE MOVING OFF TO THE
NORTHEAST. THE MLI TERMINAL MAY BE IMPACTED BY HEAVY RAIN AND LOWER
MVFR TO IFR CIGS AND VSBYS THROUGH 15Z. A LOW PRESSURE CENTER NOW IN
FAR NORTHWEST MO WILL MIGRATE NORTHEASTWARD TOWARD THE QUAD CITIES
AND NORTHERN ILLINOIS THOUGH MIDDAY. LOW CLOUDS AND FOG REDUCING
VSBYS DOWN TO 2 MILES OR EVEN LESS WILL BE POSSIBLE AT THE BRL AND
MLI TERMINALS THROUGH LATE MORNING. AFTER THE SHOWERS AND STORMS
CLEAR...SOME IFR CIGS LEFT IN THEIR WAKE DURING MIDDAY ESPECIALLY AT
CID...DBQ AND MLI. MORE SHOWERS AND SOME STORMS POSSIBLE AT THE BRL
AND MLI TERMINALS FROM 3 PM THROUGH 8 PM THIS FRIDAY EVENING...
EXPECTING MAINLY MVFR CONDITIONS WITH THIS ACTIVITY AND HEAVIER
CONVECTION REMAINING TO THE SOUTH AND SOUTHEAST OF THE LOCAL AREA.
VARIABLE WINDS THIS MORNING WITH WAKE LOW GUSTS OVER 30 KTS FROM THE
EAST AND NORTHEAST AND THEN FROM THE APPROACHING LOW PRESSURE. ONCE
THE LOW PASS OFF TO THE EAST...WINDS WILL BECOME WEST-NORTHWEST 8-15
KTS THIS AFTERNOON AND ESPECIALLY DURING THE EVENING.     ..12..

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...FLASH FLOOD WATCH UNTIL 10 AM CDT THIS MORNING 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...FLASH FLOOD WATCH UNTIL 10 AM CDT THIS MORNING FOR BUREAU-
     CARROLL-HANCOCK-HENDERSON-HENRY IL-JO DAVIESS-MCDONOUGH-
     MERCER-PUTNAM-ROCK ISLAND-STEPHENSON-WARREN-WHITESIDE.

MO...FLASH FLOOD WATCH UNTIL 10 AM CDT THIS MORNING FOR CLARK-
     SCOTLAND.

&&

LE/12

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
425 AM CDT FRI JUN 10 2011

IAZ040>042-051>054-063>068-076>078-087>089-098-099-ILZ001-002-007-
009-015>018-024>026-034-035-MOZ009-010-110930-
BUCHANAN-DELAWARE-DUBUQUE-BENTON-LINN-JONES-JACKSON-IOWA-JOHNSON-
CEDAR-CLINTON-MUSCATINE-SCOTT-KEOKUK-WASHINGTON-LOUISA-JEFFERSON-
HENRY IA-DES MOINES-VAN BUREN-LEE-JO DAVIESS-STEPHENSON-CARROLL-
WHITESIDE-ROCK ISLAND-HENRY IL-BUREAU-PUTNAM-MERCER-HENDERSON-
WARREN-HANCOCK-MCDONOUGH-SCOTLAND-CLARK-
425 AM CDT FRI JUN 10 2011

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTH CENTRAL
ILLINOIS...NORTHWEST ILLINOIS...WEST CENTRAL ILLINOIS...EAST
CENTRAL IOWA...NORTHEAST IOWA...SOUTHEAST IOWA AND NORTHEAST
MISSOURI.

.DAY ONE...TODAY AND TONIGHT

A FLASH FLOOD WATCH REMAINS IN EFFECT FOR THE ENTIRE AREA THIS
MORNING.

THUNDERSTORMS WITH MODERATE TO HEAVY RAIN ARE MOVING ACROSS THE
AREA THIS MORNING...AND HAVE ALREADY CAUSED SOME FLASH FLOODING IN
SOME AREAS. ADDITIONAL FLASH FLOODING IS POSSIBLE THIS MORNING AS
THE STORMS CONTINUE TO MOVE THROUGH THE AREA.

MORE THUNDERSTORMS ARE EXPECTED TO DEVELOP THIS AFTERNOON AND
EVENING...MAINLY ALONG AND SOUTHEAST OF A LINE FROM FAIRFIELD
IOWA...TO STERLING ILLINOIS. A FEW OF THESE STORMS MAY PRODUCE
DAMAGING WINDS OR LARGE HAIL LATER THIS AFTERNOON OR THIS EVENING.
THE STORM PREDICTION CENTER HAS PLACED THIS AREA IN A SLIGHT RISK
FOR SEVERE STORMS TODAY AND TONIGHT.

RIVER FLOODING IS EXPECTED TO DEVELOP DUE TO THE RAINFALL THE PAST
FEW DAYS...ALONG WITH RAINFALL EXPECTED TONIGHT. PLEASE SEE THE LATEST
FLOOD STATEMENTS AND FLOOD WARNINGS FOR DETAILS.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

THUNDERSTORMS RETURN TO THE FORECAST BEGINNING SUNDAY...AND
CONTINUING THROUGH WEDNESDAY AS AN UPPER LEVEL DISTURBANCE MOVES
ACROSS THE MIDWEST. AT THIS TIME IT IS TOO SOON TO DETERMINE THE
RISK OF SEVERE WEATHER.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED THIS AFTERNOON AND
EVENING...MAINLY SOUTHEAST OF A LINE FROM FAIRFIELD IA TO STERLING
ILLINOIS.

LE

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PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
339 AM CDT FRI JUN 10 2011

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0330 AM     HEAVY RAIN       1 W WASHINGTON          41.30N 91.72W
06/10/2011  M1.25 INCH       WASHINGTON         IA   TRAINED SPOTTER

            RAINFALL AMOUNT FELL OVER THE PAST TWO HOURS.

&&

12

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
407 AM CDT FRI JUN 10 2011

IAZ054-065>068-078-089-ILZ007-009-015-016-024-101100-
CARROLL-CEDAR-CLINTON-DES
MOINES-HENRY-JACKSON-LOUISA-MERCER-MUSCATINE-ROCK
ISLAND-SCOTT-WHITESIDE-
407 AM CDT FRI JUN 10 2011

...LINE OF STRONG THUNDERSTORMS SWEEPING THROUGH THE AREA...

AT 402 AM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
STRONG THUNDERSTORMS ALONG A LINE EXTENDING FROM ATALISSA TO
WAPELLO...MOVING EAST TO NORTHEAST AT 40 MPH.

* THUNDERSTORMS WILL BE NEAR...
  MANNON...WILTON AND MUSCATINE AROUND 410 AM CDT...
  BENNETT AND ELIZA AROUND 415 AM CDT...
  MILLERSBURG...ILLINOIS CITY...FAIRPORT AND DURANT AROUND 420 AM
  CDT...
  WHEATLAND AROUND 425 AM CDT...

PEA SIZE HAIL...WINDS UP TO 45 MPH...VERY HEAVY RAIN...ARE EXPECTED
WITH THESE STORMS.

EXPECT PONDING OF WATER ON ROADS AND IN LOW-LYING AREAS.

LAT...LON 4218 9010 4150 9001 4107 9128 4164 9132
TIME...MOT...LOC 0905Z 239DEG 50KT 4163 9114 4124 9111

12

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
408 AM CDT FRI JUN 10 2011

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0405 AM     FLASH FLOOD      1 W WASHINGTON          41.30N 91.70W
06/10/2011                   WASHINGTON         IA   TRAINED SPOTTER

            3RD STREET COMPLETELY COVERED WITH 2 TO 3 INCHES OF
            WATER.

&&

TO

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
451 AM CDT FRI JUN 10 2011

IAZ066-068-ILZ007-009-015>017-024-101115-
BUREAU-CARROLL-CLINTON-HENRY-MERCER-ROCK ISLAND-SCOTT-WHITESIDE-
451 AM CDT FRI JUN 10 2011

...LINE OF STRONG THUNDERSTORMS MOVING EAST OF THE MISSISSIPPI
RIVER...

AT 444 AM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
STRONG THUNDERSTORMS ALONG A LINE EXTENDING FROM NORTHWEST OF
CLINTON IOWA...TO JUST EAST OF MUSCATINE MOVING EAST AT 45 MPH.

* THUNDERSTORMS WILL BE NEAR...
  OSBORN...CLEVELAND...ANDOVER AND CLINTON AROUND 455 AM CDT...
  FULTON...EAST CLINTON AND ALBANY AROUND 500 AM CDT...
  GENESEO...CAMBRIDGE AND GARDEN PLAIN AROUND 510 AM CDT...

PEA SIZE HAIL...WIND GUSTS UP TO 50 MPH...FREQUENT CLOUD TO GROUND
LIGHTNING...VERY HEAVY RAIN...ARE ALL EXPECTED WITH THESE STORMS.

EXPECT PONDING OF WATER ON ROADS AND IN LOW-LYING AREAS.

LAT...LON 4125 8942 4125 9052 4193 9052 4193 8963
      4159 8962 4159 8942
TIME...MOT...LOC 0948Z 261DEG 42KT 4185 9037 4122 9042

12