HYDROLOGIC OUTLOOK
Warning Issue Date: 601 AM CST TUE DEC 22 2009
SIGNIFICANT RAINFALL AND SNOW MELT POSSIBLE WEDNESDAY AND
THURSDAY...
A LARGE SWATH OF MOISTURE IS FORECAST TO PUSH INTO THE STATE
THROUGH THURSDAY...ALONG WITH TEMPERATURES ABOVE FREEZING. LOOK
FOR RAIN TO DEVELOP...GENERALLY ALONG AND SOUTH OF INTERSTATE
80...BY WEDNESDAY MORNING AND IS FORECAST TO CONTINUE THROUGH
THURSDAY. THERE WILL BE PERIODS OF FREEZING RAIN IN SOME AREAS
ALONG THE CORRIDOR OF INTERSTATE 80 DURING THE MORNING HOURS
WEDNESDAY BEFORE SWITCHING TO ALL RAIN BY WEDNESDAY AFTERNOON.
RAINFALL AMOUNTS OF THREE-QUARTERS OF AN INCH TO AN INCH AND A
HALF ARE ANTICIPATED WITH THIS SYSTEM BY THURSDAY. IN
ADDITION...THE CURRENT SNOW PACK CONTAINS AROUND ONE INCH TO AN
INCH AND A HALF OF LIQUID EQUIVALENT...LEADING TO THE POTENTIAL
FOR SIGNIFICANT RUNOFF FROM RAINFALL AND SNOW MELT.
HIGH TEMPERATURES ARE EXPECTED TO BE IN THE MIDDLE TO UPPER 30S
ACROSS CENTRAL TO SOUTHERN...WITH TEMPERATURES ANTICIPATED TO
REMAIN STEADY OR SLOWLY RISING INTO THE LOWER 40S DURING THE
OVERNIGHT HOURS WEDNESDAY INTO THURSDAY. AS A RESULT...A PROLONG
PERIOD OF TEMPERATURES ABOVE FREEZING WILL RESULT IN A SIGNIFICANT
AMOUNT OF SNOW MELT DURING THE TIME FRAME.
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.
$$
PODRAZIK/COGIL
WINTER STORM WATCH
Warning Issue Date: 723 AM CST TUE DEC 22 2009
...WINTER STORM WATCH REMAINS IN EFFECT FROM WEDNESDAY MORNING
THROUGH FRIDAY AFTERNOON...
A WINTER STORM WATCH REMAINS IN EFFECT FROM WEDNESDAY MORNING
THROUGH FRIDAY AFTERNOON.
* TIMING...ALTHOUGH FREEZING DRIZZLE MAY OCCUR LATER TODAY AND
TONIGHT...THE MOST SIGNIFICANT IMPACTS WITH THIS STORM SHOULD
OCCUR WEDNESDAY MORNING THROUGH LATE FRIDAY AFTERNOON.
* STORM TOTAL ICE ACCUMULATIONS...ICING OF UP TO ONE QUARTER OF
AN INCH IS EXPECTED FROM THE HIGHWAY 30 TO HIGHWAY 20
CORRIDORS THROUGH THURSDAY WITH LESSER AMOUNTS EITHER SIDE OF
THOSE AREAS.
* STORM TOTAL SNOW ACCUMULATIONS...THE PRECIPITATION SHOULD
BECOME PRIMARILY SNOW LATE THURSDAY WITH TOTAL ACCUMULATIONS
FROM 2 TO 4 INCHES FROM ATLANTIC...DES MOINES AND GRINNELL...
UP TO OVER A FOOT ALONG AND WEST OF A DENISON...TO FORT
DODGE...TO MASON CITY LINE.
* WINDS...BRISK EAST WINDS OF 15 TO 25 MPH WILL BE IN PLACE
THROUGH MUCH OF WEDNESDAY AND THURSDAY BEFORE INCREASING EVEN
FURTHER BY FRIDAY. WINDS BY THAT TIME MAY BE SUSTAINED AT 25 TO
35 MPH WITH GUSTS EVEN HIGHER.
* VISIBILITY...DURING THE PERIODS OF HEAVY SNOW THURSDAY INTO
FRIDAY...VISIBILITIES WILL GENERALLY BE LESS THAN ONE MILE AND
EVEN DOWN TO A QUARTER MILE DURING THE HEAVIEST SNOWS. WITH
INCREASING WINDS AND SNOW COINCIDENT BY FRIDAY...BLOWING SNOW
AND GREATLY REDUCED VISIBILITIES NEAR BLIZZARD CONDITIONS ARE
EXPECTED BY THAT TIME.
* IMPACTS...TRAVEL WILL BECOME INCREASINGLY DIFFICULT IN THE
WATCH AREA ON WEDNESDAY DURING THE WINTRY MIX OF PRECIPITATION
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.
$$
SMALL
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