Severe Thunderstorm Warning 150, NWS Quad Cities, IA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1100 AM CDT MON SEP 11 2000

...WILL DO AN 18Z SOUNDING...

JUST SENT UPDATE TO ZONES.  MOST SIGNIFICANT ADJUSTMENTS WAS TO REMOVE
LATE WORDING FOR THIS AFTERNOON NORTHERN HALF OF CWA FOR
THUNDERSTORMS.  LOOKS LIKE MORNING THUNDERSTORMS NORTH OF I80 WILL
LINGER INTO THE AFTERNOON.  THUNDERSTORMS ARE OCCURRING JUST EAST OF
STRONG CAP IN AREA OF SURFACE AND 850 MOISTURE CONVERGENCE.  WAS A
LITTLE CONCERNED THAT SEVERE WEATHER POTENTIAL MIGHT SET IN QUICKER
THAN EXPECTED WITH TSRA/CU DEVELOPING SW INTO NW MO THIS MORNING.
HOWEVER TSRA IS NOT SUSTAINING ITSELF APPARENTLY DUE TO STRONG CAP
INDICATED ON LAPS.   CONTINUED THE LATE WORDING FOR SEVERE POTENTIAL
THINKING THAT VERY UNSTABLE AIRMASS WILL HAVE TO WAIT FOR FRONT TO
NEAR BEFORE SEVERE TSRA DEVELOP.  LITTLE CONCERNED ABOUT MAX TEMPS THIS
AFTERNOON  WITH STRONG MIXING...WAA AND COMPRESSIONAL HEATING.  HELD
ONTO MID 90S MOST AREAS FOR NOW AND BUMPED UP TEMPS A NOTCH NORTHWEST.
WILL HAVE TO KEEP AN EYE ON TEMPS SOUTH AND WEST THOUGH FOR FURTHER
UPDATES.

.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-MOZ009-010-120930-

SIGNIFICANT WEATHER OUTLOOK
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1159 AM CDT MON SEP 11 2000

...SEVERE WEATHER LOOKING LIKELY THIS AFTERNOON/EVENING...

A STRONG...EARLY AUTUMN COLD FRONT WILL MOVE ACROSS THE AREA THIS
EVENING. THE FRONT WILL FIRE A LINE OF THUNDERSTORMS BY MID AFTERNOON
ACROSS CENTRAL IOWA WHICH WILL MOVE EAST OVER EASTERN IOWA AND THEN INTO
NORTHWESTERN ILLINOIS BETWEEN LATE THIS AFTERNOON AND MIDNIGHT TONIGHT.
SOUTHWEST WINDS WILL INCREASE TO 20 TO 30 MPH BY AFTERNOON AHEAD OF THE
FRONT TO CREATE WINDY CONDITIONS. TEMPERATURES WILL RISE WELL INTO THE
90S BY MID AFTERNOON WITH POSSIBLY NEAR RECORD HIGHS.

A SQUALL LINE IS EXPECTED TO DEVELOP ACROSS CENTRAL IOWA THIS AFTERNOON
AND MOVE EAST INTO EASTERN IOWA...NORTHWEST ILLINOIS...AND FAR
NORTHEAST MISSOURI. THE MAIN THREAT WITH THE SQUALL LINE SHOULD BE
DAMAGING WINDS OF 60 MPH OR HIGHER AND HAIL UP TO THE SIZE OF GOLF
BALLS. HOWEVER ISOLATED TORNADOES CANNOT BE RULED OUT WITH THE SQUALL
LINE.

A BIGGER CONCERN IS FOR THE POTENTIAL DEVELOPMENT OF SUPERCELL
THUNDERSTORMS AHEAD OF THE SQUALL LINE. THE EXTREMELY UNSTABLE
ATMOSPHERE COMBINED WITH SUFFICIENT WIND SHEAR MAY RESULT IN THE
DEVELOPMENT OF TORNADIC SUPERCELLS.

AT THIS TIME...THE ENTIRE AREA HAS THE RISK FOR SEVERE WEATHER BETWEEN
3 PM AND 10 PM...WITH THE MOST LIKELY TIME OF INITIAL DEVELOPMENT
BETWEEN 4 AND 5 PM. AREAS ALONG AND NORTH OF INTERSTATE 80 MAY
EXPERIENCE MORE SIGNIFICANT AND WIDESPREAD SEVERE WEATHER. ADDITIONALLY
...ISOLATED SEVERE STORMS CAN BE EXPECTED NORTH OF HIGHWAY 30 THROUGH
OUT THE AFTERNOON.

SPOTTER ACTIVATION WILL BE NEEDED LATER THIS AFTERNOON AND INTO THE
EVENING HOURS.