Severe Thunderstorm Warning 123, NWS Quad Cities, IA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
257 PM CDT SUN JUL 9 2000

18Z SURFACE ANALYSIS HAS A SYNOPTIC LOW AT KMCK WITH A COLD FRONT
RUNNING INTO CENTRAL COLORADO. A STATIONARY FRONT RUNS NORTHEAST TO
KMHE AND THEN BECOMES A COLD FRONT RUNNING EAST NORTHEAST ACROSS
MINNESOTA AND NORTHERN WISCONSIN. ON THE MESOSCALE...MESO HIGHS WERE
NOTED NEAR KMCW AND A LITTLE EAST OF KIOW. A MESO COLD FRONT RUNS
ALONG A KFSD...KCIN...KEOK...KPIA...TO KARR VICINITY WITH ANOTHER
BOUNDARY BEHIND IT FROM KDSM TO KGBG. OTHER BOUNDARIES WERE ACROSS
WISCONSIN WITH SEVERAL TROFS FROM NEBRASKA INTO TEXAS. WATER VAPOR
AND PROFILER DATA HAS A SHORTWAVE MOVING THROUGH WESTERN IOWA WHICH
HELPED SUPPORT CONVECTION EARLIER TODAY. OTHER SHORTWAVES WERE NOTED
IN THE CENTRAL AND SOUTHERN PLAINS. A SIGNIFICANT SHORTWAVE WAS
MOVING OUT OF WYOMING INTO THE PLAINS. SATELLITE SHOW THINNING CI
DEBRIS ACROSS THE FORECAST AREA WITH SOME LOWER AC BELOW. CU WAS
DEVELOPING ALONG THE WESTERN EDGE OF THE MESO FRONT BETWEEN KFSD AND
KCNC. DVN 88D SHOWS REMNANTS OF MORNING CONVECTION AS A NARROW LINE
OVER CENTRAL ILLINOIS. MOISTURE ANALYSIS HAS 65 TO 70 DEW POINTS
OVER THE FORECAST AREA IN THE COLD POOL WHILE MID 70 DEW POINTS LIE
ON THE OTHER SIDE OF THE MESO FRONT.

PROBLEMS THIS PACKAGE ARE CLOUDS/TEMPS/PRECIP TIMING...AND POSSIBLE
NEED FOR HEADLINES.

12Z MODELS DID A FAIR JOB OF INITIALIZING THIS MORNING BUT NONE WERE
HANDLING THE MESOSCALE FEATURES AT ALL AT 18Z WHICH IS TO BE
EXPECTED. OVERALL THE AVN MAY BE THE WINNER EVER SO SLIGHTLY OVER
THE ETA. NGM NOT DOING VERY WELL BUT LATER IN ITS FORECAST CYCLE THE
POSITION OF THE SURFACE FRONT DOESN/T LOOK TOO BAD. THEREFORE WILL
GO WITH MAINLY THE ETA BUT ADJUSTED SOUTH AND WEST SLIGHTLY...AND
MIX IN A LITTLE OF THE AVN AND NGM.

MESOSCALE TO BE THE DRIVING FORCE FOR THIS PACKAGE AND ETA DOES GIVE
SOME HINTS. WEAK LLJ IN THE PLAINS TO STRENGTHEN TO 40-50 KNOTS
OVERNIGHT ALLOWING MCS/MCC TO DEVELOP IN THE MISSOURI VALLEY
SOMEWHERE BETWEEN KTQE AND KSFD. QG FORCING AND CONDENSATION
PRESSURE DEFICITS INDICATE A GENERAL EASTWARD MOVEMENT OVERNIGHT...
ROUGHLY ALONG THE H85 THERMAL GRADIENT. COMPLEX SHOULD TURN MORE
SOUTEHAST AND THEN SOUTH AS IT MOVES OVER THE FORECAST AREA LATE
TONIGHT/MONDAY MORNING. GOOD INFLOW AND HIGH PW/S TO ALLOW VERY
EFFICIENT RAINFALL PRODUCTION OVERNIGHT WITH HEAVY RAINFALL LIKELY.
SOILS OVER THE AREA ARE STILL QUITE MOIST WITH FFG VALUES 2.5 INCHES
OR LESS FOR THREE HOURS. POTENTIAL EXITS FOR 2-3 OR HIGHER AMOUNTS
OVERNIGHT INTO MONDAY SO WILL RAISE FLASH FLOOD WATCH FOR MOST OF
THE FORECAST AREA.

ON MONDAY...COLD POOL FROM MCS/MCC SYSTEM AND COLD FRONT MOVING SOUTH
TO KEEP TEMPERATURES BELOW GUIDANCE WITH PERIODS OF RAIN/TSRA FOR A
GOOD CHUNK OF THE DAY. BRIEF DRY PERIOD SHOULD BE SEEN BEFORE
ANOTHER SHORTWAVE INITIATES SOME MORE CONVECTION MONDAY NIGHT...
POSSIBLY INTO TUESDAY MORNING. COLD FRONT TO STALL JUST SOUTH OF THE
FORECAST AREA MONDAY NIGHT AND THEN BEGIN MOVING BACK NORTH AS A
WARM FRONT TUESDAY NIGHT. ANOTHER SHORTWAVE SHOULD INITIATE ANOTHER
MCS/MCC TUESDAY NIGHT IN THE PLAINS AND TRACK EASTWARD THROUGH IOWA
ALONG THE H85 GRADIENT. POTENTIAL EXITS HERE FOR ANOTHER ROUND OF
HEAVY RAIN AS WELL.

EXTENDED WISE...NOT MUCH TIME TO LOOK AT BUT LOOKS TO BE ACTIVE...
ESPECIALLY WEDNESDAY AND POSSIBLY THURSDAY WITH MORE CONVECTION.
FRIDAY FOR NOW APPEARS IT MAY BE THE BEST DAY WITH DRY CONDITIONS.

AS MENTIONED EARLIER...WILL GO BELOW GUIDANCE FOR ON MONDAY...AND
POSSIBLY FOR MUCH OF THE PERIOD.

COORDINATED WITH DSM...LSE...CHI...ILX...AND STL.

.DVN...FLASH FLOOD WATCH LATE TONIGHT AND MONDAY MORNING.
IAZ040>042-051>054-063>068-076>078-088-089
ILZ001-002-007-009-015>018-024>026-035

TI

N