Severe Thunderstorm Warning 8, NWS Quad Cities, IA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
245 PM CDT WED APR 19 2000

PLENTY TO LOOK AT TODAY.  WELCOME PRECIP THAT MOVED THROUGH
OVERNIGHT AND EARLY THIS MORNING HAS EXITED INTO NORTHERN ILLINOIS
AND SOUTHERN WISCONSIN.  IMPRESSIVE UPPER LOW HAS MOVED INTO
SOUTH-CENTRAL SOUTH DAKOTA THIS AFTERNOON.  AT THE SURFACE...THE
LOW  IN SOUTHEASTERN SOUTH DAKOTA HAS OCCLUDED AND THE NEW LOW HAS
DEVELOPED IN NORTH-CENTRAL MISSOURI AND SOUTH-CENTRAL IOWA.  WARM
FRONT EXTENDS SOUTHEASTWARD INTO EAST-CENTRAL MISSOURI  WITH A
DRYLINE SOUTHWESTWARD INTO SOUTH-CENTRAL KANSAS.
CLOUDS-DRIZZLE-GRUNGE HAVE KEPT TEMPS IN CHECK ACROSS NORTHERN PART
OF CWFA.  BREAKS IN CLOUDS NOW DEVELOPING ACROSS SOUTHERN COUNTIES
SHOULD PROVIDE JUST ENOUGH HEATING TO DESTABILIZE THE LOWER
LAYERS...THEN AS THE UPPER LOW APPROACHES THE CAP SHOULD WEAKEN
ENOUGH FOR THUNDER TO MOVE IN EARLY THIS EVENING.  REFERENCE THE SPC
DAY 1 OUTLOOK FOR A DETAILED DISCUSSION OF THE REGIONAL THREAT.

WILL KEEP MENTION OF SEVERE FOR THIS EVENING.  STORMS SHOULD BE
MOVING AT 40 TO 50 KTS AGAIN TONIGHT...SO WOULD NOT EXPECT A THREAT
OF FLASH FLOODING.  AREAS TO WATCH ARE NORTHWESTERNMOST COUNTIES
WHERE RAINFALL THIS MORNING EXCEEDED AN INCH IN SPOTS.

MODELS IN GENERAL AGREEMENT ON THE EVOLUTION OF THE UPPER LOW BUT
HAVE SOME DISCREPANCIES ON THE MOVEMENT OF THE SURFACE FEATURES.  AT
THIS POINT PREFER THE ETA SOLUTION WHICH DEFINES THE SURFACE LOW A
LITTLE MORE CLEARLY AT 00Z.

GIVEN THE STRENGTH OF THE SYSTEM...WOULD EXPECT A SIGNIFICANT CLOUD
SHIELD TO BLANKET THE AREA THURSDAY SO TEMPS WILL STRUGGLE TO CLIMB
OUT OF THE 50S.  EXPECT NGM IS TOO OPTIMISTIC CLEARING THINGS OUT
THURSDAY NIGHT SO WILL UNDERCUT GUIDANCE TEMPS FRIDAY BY TWO CATS OR
MORE AND HANG ON TO THE CLOUDS.

ON THE BRIGHT SIDE...THE WEEKEND LOOKS NICE WITH TEMPS WARMING BACK
INTO THE 70S AND LOTS OF SUN FOR EASTER EGG HUNTS.

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

33

IAZ040>042-051>054-063>068-076>078-087>089-098-099-ILZ001-002-007-009-
015>018-024>026-034-035-MOZ009-010-200300-

SIGNIFICANT WEATHER OUTLOOK...CORRECTED TYPO
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
612 PM CDT WED APR 19 2000

...POTENTIAL FOR A FEW SEVERE THUNDERSTORMS LATE THIS EVENING...MAINLY
ALONG AND SOUTH OF HIGHWAY 34...

AT 6 PM...LOW PRESSURE WAS CENTERED OVER SOUTHERN SOUTH DAKOTA WITH
A WARM FRONT DRAPED ACROSS IOWA AND ILLINOIS FROM ROUGHLY IOWA CITY TO
THE QUAD CITIES TO NEAR KEWANEE. A DRYLINE REMAINS NEARLY STATIONARY
FROM SOUTH CENTRAL IOWA THROUGH NORTHWEST MISSOURI INTO EASTERN KANSAS.

SHOWERS AND THUNDERSTORMS WHICH DEVELOPED OVER MISSOURI HAVE MOVED
QUICKLY INTO CENTRAL ILLINOIS. A LAYER OF WARM AIR ALOFT...ALSO KNOWN
AS A CAP...HAS PREVENTED CONVECTION FROM BLOSSOMING ALONG THE DRYLINE.
HOWEVER...COOL AIR ALOFT FROM AN APPROACHING UPPER LEVEL DISTURBANCE
WILL AID IN ERODING THE CAP WITH THUNDERSTORM DEVELOPMENT EXPECTED BY
10 PM OVER WESTERN MISSOURI AND PORTIONS OF EASTERN KANSAS. THESE
THUNDERSTORMS WILL LIKELY MOVE EAST INTO NORTHEAST MISSOURI...SOUTHEAST
IOWA AND WEST CENTRAL ILLINOIS AROUND MIDNIGHT AND CONTINUE THROUGH THE
OVERNIGHT. THE MAIN THREAT FROM THE THUNDERSTORMS WILL BE HEAVY RAIN...
SMALL HAIL AND GUSTY WINDS. A FEW THUNDERSTORMS MAY PRODUCE LARGE
HAIL AND DAMAGING WINDS ALONG AND SOUTH OF A MOUNT PLEASANT TO MONMOUTH
LINE.

EMERGENCY MANAGERS AND SPOTTERS OVER SOUTHEAST IOWA...NORTHEAST MISSOURI
AND WEST CENTRAL ILLINOIS SHOULD MONITOR LATER STATEMENTS AND SHORT TERM
FORECASTS. SPOTTER ACTIVATION MAY BE NEEDED LATE THIS EVENING SOUTH OF
INTERSTATE 80.

MCCLURE

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1058 PM CDT WED APR 19 2000

TIME(CDT)  .....CITY LOCATION..... STATE  ...EVENT/REMARKS...
           ....COUNTY LOCATION....

0829 PM    2 N GARRISON              IA   1.5 INCH HAIL
04/19/00   BENTON                         REPORTED BY LAW
                                          ENFORCEMENT OFFICIAL.

0915 PM    3 NE HAZLETON             IA   .88 INCH HAIL
04/19/00   BUCHANAN                       REPORTED BY LAW
                                          ENFORCEMENT OFFICIAL.

0930 PM    INDEPENDENCE              IA   WIND DAMAGE WITH .50 INCH HAIL
04/19/00   BUCHANAN                       REPOBRTED BY STORM SPOTTER