HYDROLOGIC OUTLOOK
Warning Issue Date: 529 AM CST WED DEC 23 2009
FLOODING RESULTING FROM SIGNIFICANT RAINFALL...ALONG WITH
SNOW MELT AND ICE JAMS...POSSIBLE WEDNESDAY AND THURSDAY...
A PRODIGIOUS LOW PRESSURE SYSTEM WILL BRING THE POSSIBILITY OF
FLOODING TO CENTRAL AND ESPECIALLY SOUTHERN IOWA THROUGH THURSDAY
EVENING. PRECIPITATION TYPE WILL BE A MAJOR DRIVING FORCE IN THE
FLOODING THREAT. AREAS OF FREEZING RAIN AND DRIZZLE ARE POSSIBLE
TODAY AND TONIGHT OVER CENTRAL PORTIONS OF THE AREA...WITH
GENERALLY RAIN AND ISOLATED THUNDERSTORMS EXPECTED OVER FAR
SOUTHERN IOWA. RAINFALL AMOUNTS OF A HALF INCH TO NEARLY TWO
INCHES ARE ANTICIPATED THROUGH THURSDAY NIGHT.
THE COMBINATION OF ABOVE FREEZING TEMPERATURES...ALONG WITH
SEASONALLY MODERATE TO HEAVY RAINFALL...WILL LEAD TO A POTENTIALLY
SIGNIFICANT AMOUNT OF SNOW MELT AND RUNOFF INTO AREA STREAMS.
LOCALIZED FLOODING MAY ALSO OCCUR IN OTHER AREAS...SUCH AS URBAN
AREAS...WHERE THE DRAINAGE SYSTEMS MAY BE IMPAIRED DUE TO SNOW AND
ICE CLOGGED INTAKES.
ANOTHER CONCERN IS BREAK UP ICE JAMS ON AREA RIVERS. ESTIMATED RIVER
ICE DEPTHS RANGE FROM 2 INCHES IN SOUTHEAST IOWA...TO 6 INCHES IN
CENTRAL IOWA. THE RUNOFF WILL LIKELY BE ENOUGH TO BREAK UP THE ICE
ESPECIALLY AS ONE MOVES SOUTHWARD. SINCE THE RIVER ICE IS
RELATIVELY THIN...THOUGH...ONLY MINOR...LOCALIZED PROBLEMS DUE TO
ICE JAMS ARE EXPECTED.
RIVERS MOST LIKELY TO BE AFFECTED INCLUDE THE CHARITON...DES
MOINES RIVER FROM DES MOINES DOWNSTREAM...AS WELL AS THE SOUTH
SKUNK...CEDAR CREEK...AND THE THOMPSON RIVERS. OTHER SMALLER
STREAMS AND CREEKS MAY ALSO BE AFFECTED.
KEEP CURRENT ON THE LATEST FORECASTS...INCLUDING POSSIBLE WATCHES
AND WARNINGS.
$$
PODRAZIK/ZOGG
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