HYDROLOGIC OUTLOOK
Issue Date: 259 PM CST MON DEC 21 2009
Expiration: 530 AM CST TUE DEC 22 2009

...SIGNIFICANT RAINFALL AND SNOW MELT POSSIBLE WEDNESDAY AND THURSDAY...
AN UNSEASONABLY STRONG SURGE OF MOISTURE IS EXPECTED INTO THE
STATE ON WEDNESDAY AND THURSDAY. THIS IS FORECAST TO PUSH
TEMPERATURES ABOVE FREEZING BY WEDNESDAY AFTERNOON...PRIMARILY
ALONG AND SOUTH OF INTERSTATE 80. THEREFORE...RAIN IS THE PRIMARY
PRECIPITATION TYPE EXPECTED ACROSS THE SOUTHERN THIRD TO HALF OF
CENTRAL IOWA WEDNESDAY AFTERNOON INTO THURSDAY. BETWEEN THREE-
QUARTERS AND AN INCH AND A HALF OF RAIN IS FORECAST DURING THIS
TIME. IN ADDITION...THE SNOW ON THE GROUND CONTAINS AROUND AN INCH
TO INCH AND A HALF OF WATER. THE COMBINATION OF THE RAINFALL AND
SNOW MELT WILL LEAD TO LARGE AMOUNTS OF RUNOFF.
TEMPERATURES WILL BE THE BIG FACTOR IN THE EFFICIENCY OF THE
RUNOFF FROM SNOW MELT. SHOULD READING STAY JUST ABOVE
FREEZING...SNOW MELT WILL NOT BE AS QUICK AND RUNOFF WILL BE
MUTED. HOWEVER...SHOULD TEMPERATURES REACH 40 OR HIGHER...THEN
SNOW MELT WILL BE MUCH FASTER WITH A BIGGER RESPONSE IN RUNOFF.
AREA STREAMS AND RIVERS ACROSS THE SOUTHERN HALF OF IOWA WILL
LIKELY EXPERIENCE LARGE RISES DUE TO THE COMBINATION OF RAINFALL
AND SNOW MELT BY THURSDAY AND RIVER FLOODING MAY BECOME
PROBLEMATIC. BASINS WHICH APPEAR MOST LIKELY TO BE AFFECTED
INCLUDE THE CHARITON...LOWER DES MOINES...SOUTH SKUNK...CEDAR
CREEK...AND THE THOMPSON RIVERS ACROSS THE SOUTHERN HALF OF
CENTRAL IOWA.
$$
COGIL

HAZARDOUS WEATHER OUTLOOK
Issue Date: 656 PM CST MON DEC 21 2009
Expiration: 700 PM CST TUE DEC 22 2009

Expires:200912230100;;
FLUS43 KDMX 220055
HWODMX
HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE DES MOINES IA
655 PM CST MON DEC 21 2009
IAZ037>039-047>050-057>060-070-071-230100-
HARDIN-GRUNDY-BLACK HAWK-BOONE-STORY-MARSHALL-TAMA-AUDUBON-GUTHRIE-
DALLAS-POLK-CASS-ADAIR-
655 PM CST MON DEC 21 2009
THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL IOWA.
.DAY ONE...TONIGHT
SOME LIGHT SNOW WITH MINOR ACCUMULATION IS EXPECTED TONIGHT.
.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY
A MAJOR WINTER STORM WITH SIGNIFICANT SNOW AND ICE ACCUMULATIONS
WILL IMPACT THE AREA FROM WEDNESDAY THOUGH FRIDAY. A WINTER STORM
WATCH IS IN EFFECT FOR THE AREA. PLEASE REFER TO THE NATIONAL
WEATHER SERVICE WEBSITE AT WEATHER.GOV/DESMOINES FOR FURTHER
DETAILS.
.SPOTTER INFORMATION STATEMENT...
SPOTTER ACTIVATION WILL NOT BE NEEDED...BUT SNOWFALL AMOUNTS AND
REPORTS OF ADVERSE WINTER WEATHER ARE APPRECIATED AND ENCOURAGED.
$$

WINTER STORM WATCH
Issue Date: 344 PM CST MON DEC 21 2009
Expiration: 600 PM CST FRI DEC 25 2009

...MAJOR WINTER STORMS SET TO IMPACT PORTIONS OF IOWA WEDNESDAY
THROUGH FRIDAY...
.LOW PRESSURE WILL MOVE THROUGH IOWA TONIGHT BRINGING SNOW ACROSS
THE NORTHERN HALF OF THE STATE. A MUCH MORE INTENSE SYSTEM IS
FORECAST TO LIFT INTO THE MIDWEST ON WEDNESDAY AND MEANDER SLOWLY
NORTH INTO THURSDAY AND FRIDAY BRINGING SEVERE WINTER WEATHER
CONDITIONS TO PORTIONS OF CENTRAL IOWA.
IAZ023>025-033>039-044>050-057>060-070-071-220500-
/O.NEW.KDMX.WS.A.0007.091223T1200Z-091226T0000Z/
POCAHONTAS-HUMBOLDT-WRIGHT-SAC-CALHOUN-WEBSTER-HAMILTON-HARDIN-
GRUNDY-BLACK HAWK-CRAWFORD-CARROLL-GREENE-BOONE-STORY-MARSHALL-
TAMA-AUDUBON-GUTHRIE-DALLAS-POLK-CASS-ADAIR-
INCLUDING THE CITIES OF...POCAHONTAS...HUMBOLDT...CLARION...
SAC CITY...ROCKWELL CITY...FORT DODGE...WEBSTER CITY...ELDORA...
GRUNDY CENTER...WATERLOO...DENISON...CARROLL...JEFFERSON...
BOONE...AMES...MARSHALLTOWN...TOLEDO...AUDUBON...GUTHRIE CENTER...
ADEL...DES MOINES...ATLANTIC...GREENFIELD
344 PM CST MON DEC 21 2009
...WINTER STORM WATCH IN EFFECT FROM WEDNESDAY MORNING THROUGH
FRIDAY AFTERNOON...
THE NATIONAL WEATHER SERVICE IN DES MOINES HAS ISSUED A WINTER
STORM WATCH...WHICH IS IN EFFECT FROM WEDNESDAY MORNING THROUGH
FRIDAY AFTERNOON.
* TIMING...WEDNESDAY MORNING THROUGH LATE FRIDAY AFTERNOON.
* STORM TOTAL ICE ACCUMULATIONS...UP TO ONE QUARTER INCH FROM THE
HIGHWAY 30 TO HIGHWAY 20 CORRIDORS WITH LESSER AMOUNTS FARTHER
NORTH.
* STORM TOTAL SNOW ACCUMULATIONS...4 TO 6 INCHES ALONG THE
SOUTHERN EDGE OF THE WATCH AREA UP TO OVER A FOOT ALONG AND WEST
OF A CARROLL TO MASON CITY LINE.
* WINDS...EASTERLY WINDS AT 10 TO 20 MPH ON WEDNESDAY INTO
THURSDAY BECOMING NORTHERLY AT 20 TO 30 MPH WITH HIGHER GUSTS ON
FRIDAY.
* VISIBILITY...SNOW AREAS WILL SEE VISIBILITIES GENERALLY LESS
THAN ONE MILE FOR THE DURATION OF THE STORM WITH FREQUENT
VISIBILITIES OF ONE HALF TO ONE QUARTER OF A MILE IN THE HEAVIER
SNOWS. WITH INCREASING WINDS THURSDAY NIGHT AND FRIDAY...BLOWING
SNOW AND REDUCED VISIBILITIES ARE EXPECTED IN THE WATCH AREA.
* IMPACTS...TRAVEL WILL BECOME INCREASINGLY DIFFICULT IN THE WATCH
AREA ON WEDNESDAY AND CONTINUE TO BE DIFFICULT INTO THURSDAY AND
FRIDAY AS SNOW ACCUMULATES AND WINDS INCREASE. IN THE HEAVIEST
SNOW AREAS...TRAVEL MAY BECOME NEARLY IMPOSSIBLE DUE TO BLOWING
AND DRIFTING SNOW THURSDAY NIGHT INTO FRIDAY.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
A WINTER STORM WATCH MEANS THERE IS A POTENTIAL FOR SIGNIFICANT
SNOW...SLEET...OR ICE ACCUMULATIONS THAT MAY IMPACT TRAVEL.
CONTINUE TO MONITOR THE LATEST FORECASTS.
$$
COGIL