River Flood Warning 105, NWS Quad Cities, IA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
300 PM CDT WED AUG 19 2009

.SYNOPSIS...
WARM FRONT LIFTED NORTH ACROSS ILLINOIS AND SOUTHERN IOWA THIS
AFTERNOON.  IN SPITE OF 1000-2000 J/KG CAPES...WIDESPREAD CLOUD
COVER LIMITED SEVERE THREAT. PRECIPITABLE WATERS 1.75 TO 2.25 INCHES
RESULTED IN HEAVY RAINFALL...OVER AN INCH IN 15 MINUTES IN PLACES.
ALOFT...LONG WAVE TROUGH OVER THE CENTRAL US...WITH A STRONG SHORT
WAVE EJECTING ONTO IA/MN THIS AFTERNOON AND ANOTHER JUST BEHIND IT
OVER THE DAKOTAS.  ASSOCIATED COLD FRONT EXTENDED FROM MANITOBA
THROUGH THE EASTERN DAKOTAS AND INTO NORTHWEST KS.

&&

.SHORT TERM...TONIGHT THROUGH THURSDAY...
WARM FRONT WILL CONTINUE TO MOVE THROUGH THE REGION THIS AFTERNOON
AND EVENING. FORECAST SOUNDINGS INDICATE A STRENGTHENING CAP IN THE
WARM SECTOR AND LAPS ANALYSIS SHOWS SIGNIFICANT STABILIZATION BEHIND
THE CURRENT CONVECTION.  THE MAIN EVENT LOOKS TO BE AFTER MIDNIGHT
WITH DEWPOINTS 70+...STRONG DYNAMICS WITH THE MAIN SHORT WAVE...AND
CONVERGENCE ALONG THE COLD FRONT. SOUNDINGS INDICATE STRONG WIND
FIELDS WITH 500 MB WINDS OF 60 KNOTS AND PRECIPITABLE WATERS 2-2.5
OVERNIGHT...SUGGESTING POTENTIAL FOR DAMAGING WINDS AND LOCALLY
HEAVY RAINFALL.

COLD FRONT CLEARS THE AREA BY 12Z THURSDAY.  POTENTIAL EXISTS FOR
BRIEF DRY SLOT THURSDAY MORNING BEFORE THE WRAP AROUND CLOUDS WORK
IN.

.LONG TERM...
STRONG SURFACE GRADIENT...COLD ADVECTION...CLOUD COVER... AND
SCATTERED SHOWERS WILL BRING A SOMEWHAT BLUSTERY FRIDAY WITH
FORECAST TEMPS NEAR RECORD COOL HIGHS. THROUGH THE END OF THE
WEEK...SURFACE LOW DEEPENS AND UPPER TROUGH SLOWLY DEEPENS...DIGS
AND EDGES EASTWARD. RIDGE AXIS DOES NOT SETTLE INTO THE AREA UNTIL
LATE IN THE WEEKEND.  NET RESULT FOR THE UPPER MISSISSIPPI VALLEY
WILL BE CONTINUED COLD ADVECTION AND COOL PATTERN THROUGH SUNDAY.

BY MONDAY NEXT WEEK...UPPER LOW CLEARS NEW ENGLAND AND UPPER PATTERN
IS DOMINATED BY  BUILDING RIDGE OVER THE CONUS.  SURFACE RIDGE IS
PROGGED TO SPAN THE OHIO VALLEY BY EARLY NEXT WEEK...CUTTING OFF THE
GULF....THEN FLATTEN TUESDAY INTO WEDNESDAY AS THE NEXT COLD FRONT
PUSHES INTO NORTHERN PARTS OF THE AREA.  WILL KEEP LOW POPS FOR
TUESDAY NIGHT INTO WEDNESDAY WITH THIS FRONT FOR NOW AND MONITOR
TIMING AND FORCING IN LATER FORECASTS.  ..33..

&&

.AVIATION...
MVFR CIGS THROUGH THE PERIOD WITH OCCASIONAL SHOWERS AND
THUNDERSTORMS.

&&

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

HAASE/33/HAASE

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1211 PM CDT WED AUG 19 2009

IAZ040>042-051>054-063>068-076>078-087>089-098-099-ILZ001-002-007-
009-015>018-024>026-034-035-MOZ009-010-201630-
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-
1211 PM CDT WED AUG 19 2009

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...THIS AFTERNOON AND TONIGHT

SHOWERS AND SCATTERED THUNDERSTORMS WILL MOVE THROUGH THE OUTLOOK
AREA THIS AFTERNOON AHEAD OF A WARM FRONT. SUPERCELLS ARE POSSIBLE
ALONG THE WARM FRONT...ESPECIALLY IN SOUTHEAST IOWA...WESTERN
ILLINOIS AND NORTHEAST MISSOURI. TORNADOES...DAMAGING WINDS AND
LARGE HAIL ARE POSSIBLE.

THE ATMOSPHERE WILL BECOME EVEN MORE UNSTABLE TONIGHT AS THE WARM
FRONT LIFTS TO THE NORTHEAST OF THE OUTLOOK AREA. STRONG TO SEVERE
THUNDERSTORMS CAN BE EXPECTED TONIGHT...MAINLY AFTER 10 PM. THE MAIN
THREAT FROM THESE STORMS WILL BE DAMAGING WINDS IN EXCESS OF 60 MPH.
STRONG DYNAMICS AND A STRONG COLD FRONT WILL BE ADVANCING FROM THE
WEST WHICH SHOULD TRIGGER NUMEROUS THUNDERSTORMS. LOCALLY HEAVY
RAINFALL OF AT LEAST 1 TO 2 INCHES IS ALSO LIKELY.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

THUNDERSTORMS WILL LINGER INTO THURSDAY MORNING EAST OF THE
MISSISSIPPI RIVER BUT SEVERE WEATHER IS NOT EXPECTED.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED THIS AFTERNOON AND AGAIN LATE THIS
EVENING AND OVERNIGHT.

HAASE