Severe Thunderstorm Warning 37, NWS Quad Cities, IA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
305 PM CDT WED MAY 8 2002

...SEVERE POTENTIAL FOR ONE MORE NIGHT...

AFTERNOON CONVECTION JUST NOW TAKING OFF IN EASTERN KS INTO CENTRAL
MO IN WARM SECTOR OF LOW OVER SOUTH CENTRAL KS. SURFACE ANALYSIS
SHOWED COLD FRONT EXTENDING NORTH TO SECOND WEAKER LOW AT 18Z N OF
OMA WITH MAIN WARM SYNOPTIC WARM FRONT SE TO W CENTRAL IL. MUCH OF
DVN CWFA HAS HAD FULL SUNSHINE TODAY WITH CAP IN PLACE. LAPS SB
CAPES AT 18Z IN 2K TO 3K J/KG RANGE IN CENTRAL IA AND PORTIONS OF SE
IA. VISIBLE SATELLITE SHOWS TRIPLE POINT OVER SW IA MOVING NE AND
WITH 3MB PRESSURE FALLS CENTERED OVER N CENTRAL IA AND SIMILAR
MAGNITUE RISES OVER E CENTRAL NEB...THE LOW AND THIS FEATURE SHOULD
CONTINUE NE THROUGH LATE AFTERNOON. PER SPC DISCUSSION...LOW LEVEL
SHEAR AND INSTABILITY WILL BE FAVORABLE FOR FEW SUPERCELLS IN FAR SW
LATE AFTERNOON INTO EVENING...THEN THREAT TURNS INTO LINEAR STORMS
WELL AHEAD OF FRONT IN EVENING WITH DAMAGING WIND MAIN THREAT.
UPSTREAM CONVECTION ALONG NUMEROUS MESOSCALE BOUNDARIES IN MO AND
EASTERN KS MAY AGAIN LIMIT CONVECTION INITIALLY. HOWEVER...WITH
WIDESPREAD SUNSHINE AND CONSIDERABLY MORE IMPRESSIVE UPPER
DIVERGENCE AND LOW TO MID LEVEL FORCING TONIGHT...THUNDERSTORMS AND
SEVERE POTENTIAL LOOKS MUCH MORE FAVORABLE THAN PAST COUPLE NIGHTS.

MODELS ARE SIMILAR WITH H5 LOW MOVING ACROSS MT THIS AFTERNOON AND
NORTH OF CWFA ON THURSDAY. SOME DIFFERENCES APPEAR IN SURFACE
PRESSURE FEATURES...WITH META HAVING BEST HANDLE WITH DOUBLE LOW
STRUCTURE AT 18Z AND THUS FAVORED MODEL FOR SHORT TERM. ALL HAVE
SIMILAR TIMING OF FROPA THAT IS A LITTLE LATER THAN PREVIOUS RUNS.
FOLLOWING META...FRONT PASSES MISS RIVER AT 06Z. BIGGEST SEVERE
THREAT WILL BE TO WEST...WITH SOME DAMAGING WIND POSSIBLE WITH
ORGANIZED SQUALL LINE AFTER MIDNIGHT IN NW IL.

HAVE LET FLOOD WATCH THAT WAS OUT FOR SOUTH TODAY EXPIRE SINCE
FLOODING POTENTIAL NOW SIGNIFICANTLY REDUCED. SINCE HEAVY RAINS
FAILED TO MATERIALIZE LAST TWO NIGHTS AND GROUND IN SOUTH HAS HAD
TIME TO DRY. DESPITE POTENTALLY HEAVY RAINFALL IN STORMS TONIGHT DUE
TO ABUNDANT MOISTURE...RELATIVELY FAST MOVEMENT WOULD LIMIT TOTALS
TO RANGE AROUND .75 TO 1.2 AT BEST. MOST THREATENED WILL BE FAR SE
IA ZONES AND ADJACENT MO AND IL ZONES WHERE 1 HOUR FFG FROM .9 TO
1.1 AND WILL HAVE TO MONITOR IF CELLS AHEAD OF FRONT BEGIN TO TRAIN.

KEPT LIKELY POPS ZONES TONIGHT...WITH SEVERE WORDING ALL ZONES AND
INCLUDING HAIL MAINLY IN SE IA ZONES FOR EVENING. LOOKS NOW LIKE
MOST OF BACK EDGE RAIN WILL END BY SUNRISE AND REDUCED EARLY FRIDAY
POPS TO 30 PERCENT AND THEN ONLY IN NW IL ZONES. BREEZY AND COOL
MAIN MESSAGE FOR THURSDAY AND WITH AMOUNT OF COLD AIR WRAPPING
AROUND AND FORECAST H85 TEMPERATURES OF -2 TO AROUND +1...WILL
UNDERCUT GUIDANCE AND STAY IN 50S FOR HIGHS. W-NW WINDS WILL BE IN
WINDY CRITERIA. MAINLY FOLLOWED AVN FRIDAY AND BEYOND AS IT HAS BEEN
FAIRLY CONSISTENT WITH SIGNIFICANT RAINFALL SATURDAY AND SUNDAY WITH
NEXT SERIES OF H5 WAVES MOVING ALONG BAROCLINIC ZONE THAT REDEVELOPS
ACROSS IA AND NORTHERN IL. RAISED SATURDAY TO LIKELY WORDING...BUT
KEPT CHANCE FOR SUNDAY THROUGH SUNDAY NIGHT BEFORE MAIN H5 LONGWAVE
TROUGH MOVES THROUGH. IN EXTENDED...NW FLOW AND LOW LEVEL RIDGING
DOMINATES MON AND TUE. MRF CONTINUING TREND OF RAIN CHANCES FOR
THURSDAY WITH NEXT FRONTAL PASSAGE AND BROUGHT IN CHANCE FOR
AFTERNOON SHOWERS.

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

DLS