Flooding in Illinois, February 24, 2001

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
245 AM CST SAT FEB 24 2001

SIMPLY PUT...MODELS INITIALIZED POORLY. FEATURES NOT CAPTURED AND LARGE
MASS FIELD ERRORS MEANS USE OUTPUT WITH CAUTION. RAW DATA THROUGH 06Z
WOULD SUGGEST THE UPPER LEVEL SYSTEM OVER THE ROCKIES IS STRONGER THAN
WHAT THE MODELS INDICATE. ONLY THING MODELS AGREE ON IS THAT SYSTEM
WILL STRENGTHEN DURING THE DAY WITH LLJ OF 70+ KNOTS. CURRENT
ISENTROPIC LIFT GENERATING FZRA OVER NORTHERN HALF CWA. CONTINUED WAA
RAISING TEMPERATURES...ALBEIT SLOWLY AND THUS WILL ALLOW PRECIP TO
CHANGE TO LIQUID FORM. PLENTY OF INSTABILITY ALOFT TO BRING THREAT OF
TSRA DEVELOPMENT OVER SOUTH HALF OR SOUTHEAST THIRD OF CWA TODAY INTO
EARLY EVENING. RUC PROBABLY BEST OF ANY MODELS SINCE IT CAN CORRECT
ERRORS IN THE MASS FIELD WHEN RUN EACH HOUR. BASED ON THAT...RUC
SUGGESTS A POSSIBLE BREAK/DECREASE IN PRECIP DURING THE DAY SATURDAY.
CURRENT NATIONAL RADAR TRENDS SUGGEST THIS IS PLAUSIBLE. OTHER MODELS
VARY IN SOLUTIONS SUGGESTING DRY SLOT TO MOVE OVER THE AREA LATE
TODAY/TONIGHT WHILE OTHERS DO NOT.

GOING ON THE ASSUMPTION THAT THE 12 HR FORECAST OF THE 24/06Z RUC IS
CORRECT...EXTRAPOLATION OF DRY PUNCH WOULD PLACE IT JUST EAST OF THE
CWA TONIGHT. THIS WOULD THEN LEAVE MUCH IF NOT ALL CWA IN DEFORMATION
ZONE AND ASSOCIATED PRECIP. FORECAST SOUNDINGS INDICATE CAA STARTING
TONIGHT WOULD ALLOW PRECIP TO CHANGE FROM RA TO SN FROM WEST TO EAST
OVERNIGHT. AREAS ALONG/EAST MISSISSIPPI MAY HOLD OFF UNTIL SUNDAY AM
BEFORE CHANGE OVER STARTS.

SEE NO REASON TO DROP ICE STORM WARNING OVER NORTH THIRD OF CWA FOR
MORNING HOURS. FLOOD WATCH ANOTHER STORY. MODELS NOT GENERATING AS
MUCH QPF AS FROM EARLIER RUNS. THIS LIKELY DUE TO THE POOR
INITIALIZATION. DUE TO UNCERTAINTIES...WILL KEEP CURRENT FLOOD WATCH
IN PLACE FOR TODAY/TONIGHT.

COORDINATED WITH LSE...DSM...CHI.

.DVN...FLOOD WATCH ENTIRE CWA TODAY AND TONIGHT.
IA...ICE STORM WARNING THIS MORNING.
IAZ040>042-051>054
IL...ICE STORM WARNING THIS MORNING.
ILZ001-002-007
MO...NONE.

SCHULTZ

IAZ040>042-051>054-063>068-076>078-087>089-098-099-ILZ001-002-007-009-
015>018-024>026-034-035-MOZ009-010-251100-

SIGNIFICANT WEATHER OUTLOOK
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
500 AM CST SAT FEB 24 2001

...VERY ACTIVE WEATHER...

A POWERFUL STORM SYSTEM WILL AFFECT THE REGION TODAY AND TONIGHT
BRINGING A VARIETY OF WEATHER. A STRONG LOW LEVEL JET OF WAS
TRANSPORTING LARGE AMOUNTS OF WARM...MOIST AIR NORTH FROM THE GULF OF
MEXICO. THIS IS EVIDENT BY DEW POINTS IN THE 40S ACROSS KANSAS.

STRONG ISENTROPIC LIFT FROM THE LOW LEVEL JET WILL CONTINUE TO PRODUCE
FREEZING RAIN THIS MORNING...NORTH OF A LINE FROM MARENGO TO STERLING
WITH ICE ACCUMULATIONS UP TO ONE HALF INCH. THE FREEZING RAIN WILL
CHANGE TO ALL RAIN LATE THIS MORNING AS THE WARMER AIR BECOMES DEEPER.

RAIN...HEAVY AT TIMES CAN BE EXPECTED ACROSS EASTERN IOWA...NORTHWEST
ILLINOIS...AND FAR NORTHEAST MISSOURI TODAY AND TONIGHT. THUNDERSTORMS
ARE EXPECTED...ESPECIALLY THIS AFTERNOON AND EVENING SOUTH OF INTERSTATE
80. STRONG STORMS ARE POSSIBLE SOUTH OF AN OTTUMWA TO GALVA LINE. THE
MAIN THREAT FROM THESE STORMS WOULD BE STRONG WINDS. ADDITIONALLY...THE
RAIN COMBINED WITH THE WARM AIR MAY PRODUCE WIDESPREAD DENSE FOG NORTH
OF AN OSKALOOSA TO ROCKFORD LINE.

WIDESPREAD RAINFALL OF 1 TO 2 INCHES...WITH LOCALLY HIGHER AMOUNTS...
ARE EXPECTED BY SUNRISE SUNDAY. A BRIEF BREAK OF UP TO 4 HOURS IN THE
RAIN IS EXPECTED LATE THIS MORNING OR AFTERNOON.

IF THE HEAVY RAIN DEVELOPS...ALL MISSISSIPPI RIVER TRIBUTARIES ACROSS
EASTERN IOWA...NORTHWEST ILLINOIS...AND FAR NORTHEAST MISSOURI WOULD
POTENTIALLY BE IMPACTED BY FLOODING LATE THIS WEEKEND AND INTO NEXT
WEEK. THE MAIN STEM MISSISSIPPI WOULD EXPERIENCE SOME RISES AS WELL.

COLDER AIR BEING PULLED INTO THE REGION TONIGHT AND SUNDAY WILL CHANGE
THE RAIN OVER TO SNOW. SOME ACCUMULATION IS POSSIBLE TONIGHT WEST OF
THE MISSISSIPPI. THE EXACT AMOUNT IS DEPENDENT ON HOW FAST THE COLD AIR
ARRIVES. CURRENT INFORMATION SUGGESTS AN INCH OR TWO.

EMERGENCY MANAGERS AND HIGHWAY DEPARTMENTS SHOULD LISTEN TO LATER
FORECASTS AS RAIN AND SNOW THREATS BECOME BETTER DEFINED. SPOTTER
ACTIVATION IS NOT ANTICIPATED.

SCHULTZ

LOCAL STORM REPORT
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
800 AM CST SAT FEB 24 2001

...ICE ACCUMULATION THROUGH 7AM CST...

COUNTY              STATE    ACCUMULATION
---------           ------   ------------
CARROLL               IL          1
JO DAVIES             IL       1/4-1/2
STEPHENSON            IL       1/4-1/2
WHITESIDE             IL       1/8-1/4
BENTON                IA       1/4-1/2
BUCHANAN              IA       1/8-1/4
CEDAR                 IA       1/8-1/4
CLINTON               IA       1/8-1/4
DUBUQUE               IA       1/8-1/4
JONES                 IA       1/8-1/4
SCOTT                 IA       1/8-1/4

ICE ON ROADWAYS CONTINUES TO MELT ACROSS THE AREA AS OF
8 AM. TRAVEL CONDITIONS WILL IMPROVE THROUGH THE DURATION
OF THE MORNING HOURS.

A SPECIAL THANKS GOES OUT TO THE LAW ENFORCEMENT AGENCIES
WHICH CONTRIBUTED TO THIS REPORT THIS MORNING.

ERVIN