Severe Thunderstorm Warning 107, NWS Quad Cities, IA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
350 PM CDT SUN JUL 6 2003

SPOTTY STRONG CONVECTION ON GOING ALONG AND EAST OF THE MS RIVER
LATE THIS AFTERNOON IN ASSOCIATION WITH MCV OVER CENTRAL WI. NICE
OUTFLOW SHOWING UP FROM KAWG EAST TO KMLI ON 88D IMAGERY WITH
VISIBLE SAT IMAGE SHOWING BOUNDARY AS FAR WEST AS
KDMX.  19Z LAPS ANALYSIS SHOWING AIR SOUTH OF BOUNDARY QUITE
UNSTABLE WITH CAPES AROUND 4000J/KG COURTESY OF LOW TO MID 70
DEWPOINTS AND TEMPS AROUND 90.  SURFACE OBS ALSO SHOWING GOOD FLOW
INTO THE BOUNDARY WITH SSW WINDS AROUND 15 KTS AND GUSTS AROUND
20KTS.  ALSO OF INTEREST IS THE BAND OF CU FROM SOUTHEAST INTO
NORTHWEST IOWA.  SO FAR NOT MUCH INDICATION OF ANY HAPPENING IN THIS
VICINITY. HOWEVER CU IS IN A  REGION OF  LOW LEVEL MOISTURE
CONVERGENCE AND WAA.  BEST 3HR PRESS FALL LOCATED OVER CENTRAL AND
NW IOWA AT 19Z. WILL HAVE TO WATCH THIS CU FIELD FOR DEVELOPMENT
THOUGH THE EVENING HOURS.  MID LEVEL S/W MOVING THROUGH SOUTH
CENTRAL CANADA THIS AFTERNOON NOT PRODUCING MUCH IN THE WAY OF TSRA
SO FAR.

RATHER MESSY FORECAST THROUGH MID WEEK WITH BOUNDARIES REMAINING IN
THE AREA THROUGH THE PERIOD AND IMPULSES MOVING ALONG SOUTHERN
PERIPHERY OF STRONGER MID LEVEL FLOW.  AS A RESULT WILL HAVE ALMOST
CONTINOUS CHANCE POPS FOR TSRA THROUGH MID WEEK.  FOR TONIGHT...TWO
AREAS OF CONCERN.  ONE IS THE CU FIELD FROM SOUTHEAST INTO NORTHWEST
IOWA...THEN THE CONVECTIVE COMPLEX EXPECTED TO DEVELOP OVER THE
NORTHERN PLAINS AND DIVE SOUTHEAST INTO THE MS VALLEY LATE TONIGHT.
EXPECT TO SEE SOME TSRA DEVELOPMENT ALONG THE CU FIELD BY MID
EVENING.  DUE TO THE EXTREME INSTABILITY OVER SOUTHERN HALF OF
IOWA...IF CONVECTION TAKES OFF IT SHOULD GO QUICKLY TO SEVERE.  ALSO
WITH AMPLE MOISTURE (KILX 18Z SOUNDING HAD PWS OF 1.6) LOCALLY HEAVY
RAINS WILL BE POSSIBLE. LATER TONIGHT...COMPLEX EXPECTED TO MOVE OUT
OF NRN PLAINS AND ACROSS THE NERN HALF OF THE CWA. BECAUSE OF THESE
TWO ISSUES...WILL INCLUDE SEVERE WORDING FOR MUCH OF CWA TONIGHT.
THERE STILL SHOULD BE SOME ONGOING CONVECTION IN THE EAST MONDAY
MORNING. SURFACE BOUNDARY PROGGED TO SETTLE IN OVER CENTRAL/SOUTHERN
IOWA BY MONDAY AFTERNOON AND REMAIN THERE THRU TUESDAY MORNING.
THUS HAVE KEPT HIGHEST POPS NORTH OF THE BOUNDARY OVER NORTHERN HALF
OF CWA.  MODELS SUGGEST THAT BOUNDARY MAY BE FORCED FUTHER SOUTH
TUESDAY AND HAVE BACKED OFF POPS ACROSS THE NORTH TUESDAY EVENING.
GFS/ETA SUGGEST THAT SURFACE WAVE WILL DEVELOP ALONG THE BOUNDARY
TUESDAY NIGHT OVER THE NORTHERN PLAINS AND DROP SOUTHEAST THU
SOUTHERN  CWA WEDNESDAY NIGHT. IF THIS SCENARIO VERIFIES...WE SHOULD
SEE ANOTHER ROUND OF SIGNIFICANT SEVERE WX AND HEAVY RAINS.  LATER
SHIFTS WILL HAVE TO MONITOR FOR POSSIBLE FFA.

THURSDAY THROUGH SUNDAY
LONG RANGE MODELS ARE IN DECENT AGREEMENT THAT BOUNDARY WILL BE
FORCED WELL SOUTH OF CWA IN RESPONSE TO RIDGE BUILDING OVER WESTERN
U.S.  WILL GO WITH DRY FORECAST UNTIL SUNDAY WHEN GFS DRIVES ANOTHER
FRONT THROUGH THE REGION.

.DVN...
IA...NONE.
IL...NONE.
MO...NONE.

DLF

IAZ040>042-051>054-063>068-076>078-087>089-098-099-ILZ001-002-007-
009-015>018-024>026-034-035-MOZ009-010-071000-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
425 PM CDT SUN JUL 6 2003

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

.DAY ONE...EVENING AND OVERNIGHT...

AS WIDELY SCATTERED SHOWERS AND THUNDERSTORMS EXIT THE AREA TO THE
EAST THIS AFTERNOON...ATTENTION THEN TURNS TO THE WEST AND SOUTH.
A WEAK BOUNDARY DRAPED ACROSS CENTRAL AND SOUTHERN IOWA THIS
AFTERNOON MAY BECOME THE FOCUS FOR MORE SCATTERED THUNDERSTORM
DEVELOPMENT THIS EVENING. VERY WARM AND MOIST AIR CONTINUES TO
POOL INTO THIS FEATURE ON THE NOSE OF A SOUTHWEST BREEZE OVER
SOUTHERN IOWA. THUNDERSTORMS MAY DEVELOP IN THE VICINITY OF THE
BOUNDARY OVER THE NEXT FEW HOURS...AND AFFECT AREAS ALONG AND SOUTH
OF A LINE FROM MARENGO...TO MUSCATINE...AND TO MONMOUTH. IF ANY
STORMS DO DEVELOP THIS EVENING...THEY WILL FEED ON THE VERY MOIST AND
UNSTABLE AIR AND MAY REACH SEVERE LEVELS. THE HIGHEST RISKS WILL BE
FOR DAMAGING WINDS OF UP TO 65 MPH AND LARGE HAIL UP TO THE SIZE OF
QUARTERS. THE STORMS WILL ALSO BE CAPABLE OF PRODUCING LOCALLY VERY
HEAVY RAINFALL AT RATES OF 1 TO 2 INCHES AN HOUR. IF STORMS DEVELOP
AND AFFECT PORTIONS OF SOUTHEAST IOWA...WHICH WAS HARD HIT BY HEAVY
RAINFALL SATURDAY EVENING...FLASH FLOODING PROBLEMS COULD ARISE
QUICKLY. THIS INCLUDES THE KEOSAUQUA...DONNELLSON...AND KEOKUK AREAS
IN FAR SOUTHEAST IOWA...AND THE KAHOKA AREA IN FAR NORTHEAST
MISSOURI.

AFTER THE EVENING THUNDERSTORM POTENTIAL...ANOTHER THREAT IN THE FORM
OF A SEVERE THUNDERSTORM COMPLEX MAY AFFECT PORTIONS OF THE AREA LATE
TONIGHT AND EARLY MONDAY MORNING. THUNDERSTORMS DEVELOPING THIS
EVENING ACROSS NORTHERN AND CENTRAL MINNESOTA...AND INTO SOUTH
DAKOTA...MAY LOOK TO FORM INTO A LARGE SYSTEM OF STORMS AND
PROPAGATE TOWARD NORTHEAST IOWA AFTER MIDNIGHT. THESE STORMS COULD
FORM INTO A BIG BOWING COMPLEX THAT MAY SWEEP ACROSS AREAS ALONG AND
NORTH OF THE INTERSTATE 80 CORRIDOR FROM 3 AM TO 7 AM. IF THIS LARGE
BOW ECHO MATERIALIZES AND MAKES IT DOWN INTO THE LOCAL AREA...
STRAIGHT LINE WINDS OF 60 TO 70 MPH MAY BE PRODUCED BY IT. LATEST
INDICATIONS SUGGEST THAT THE WIND THREAT MAY AFFECT THE DUBUQUE AND
CEDAR RAPIDS AREAS BY AROUND 3 AM. STAY TUNED FOR LATER UPDATES AND
FORECASTS CONCERNING THIS LATE NIGHT STORM POTENTIAL.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY...

ANOTHER ROUND OF STRONG TO SEVERE STORMS IS ANTICIPATED MONDAY NIGHT
AS A COMPLEX OF THUNDERSTORMS DROPS OUT OF SOUTHWEST MINNESOTA...
THROUGH THE MID MISSISSIPPI RIVER VALLEY.  THE GREATEST POTENTIAL FOR
SEVERE STORMS WILL BE NORTH OF INTERSTATE 80 WITH THE GREATEST RISK
OF SEVERE WEATHER IN THE FORM OF DAMAGING WINDS AND ISOLATED
TORNADOES.

THUNDERSTORMS WILL CONTINUE TO THREATEN THE REGION TUESDAY THROUGH
WEDNESDAY...AS A FRONTAL BOUNDARY STALLS ACROSS SOUTHERN IOWA AND
NORTHERN MISSOURI.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS POSSIBLE THIS EVENING AREA WIDE...THEN LIKELY
LATE TONIGHT ALONG AND NORTH OF INTERSTATE 80. SPOTTER ACTIVATION MAY
ALSO BE NEEDED AGAIN MONDAY AND TUESDAY NIGHT.

&&

MORE INFORMATION MAY BE OBTAINED AT THE FOLLOWING URL:
HTTP://WWW.CRH.NOAA.GOV/DVN

DLF/12