Hydrometeorological Discussion
Issued by NWS North Central River Forecast Center

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AGUS73 KMSR 241712
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HYDROMETEOROLOGICAL FORECAST DISCUSSION
NWS NORTH CENTRAL RIVER FORECAST CENTER TWIN CITIES/CHANHASSEN MN
1115 AM CST MON NOV 24 2014

...PRECIPITATION...

DURING THE PAST 24-HOURS...A LARGE AREA OF PRECIPITATION FELL OVER
MUCH OF THE NCRFC REGION. THE PRECIPITATION WAS GENERALLY IN THE
FORM OF RAIN...BUT SOME ISOLATE SNOWFALL WAS REPORTED AS
COOLER TEMPERATURES MOVED IN DURING THE OVERNIGHT HOURS. THE
HEAVIEST  BAND OF  LIQUID TOTALS OF 1 - 2 PLUS INCHES FELL IN
SOUTHEAST IOWA...MISSOURI...ILLINOIS...INDIANA...SOUTHERN
WISCONSIN AND MUCH OF MICHIGAN. IN A LINE FROM SOUTHWESTERN IOWA
TO THE UPPER PENINSULA OF MICHIGAN... LIQUID TOTALS RANGED FROM 0.25
TO 0.50 INCHES.

DURING THE NEXT 24-HOURS...RAIN..SNOW...AND RAIN TURNING TO SNOW
IS FORECAST FOR WISCONSIN...MICHIGAN...NORTHERN ILLINOIS AND
NORTHERN INDIANA. LIQUID TOTALS  0.25 TO 0.75 IS POSSIBLE OVER
THIS REGION.


...HYDROLOGIC CONDITIONS...

MINOR FLOODING IS FORECAST FOR A FEW SITES IN NORTHERN INDIANA AND
LOWER MICHIGAN AS A RESULT OF WEEKEND RAINS AND SNOWMELT.

THIS HAS BEEN A CHALLENGING EVENT TO FORECAST FOR A NUMBER OF
REASONS..

   - PRECIPITATION GAGE QUALITY CONTROL

     QUALITY CONTROL OF TIPPING BUCKET PRECIPITATION GAGES HAS
     BEEN DIFFICULT BECAUSE WARM TEMPERATURES HAVE MELTED SNOW
     THAT ACCUMULATED IN THEM.

     OTHER GAGES HAVE BEEN COVERED
     AND REPORTED ZEROS.  IN EITHER CASE.. THEY DO NOT REPRESENT
     THE AMOUNT OF RAIN THAT FELL.

   - RIVER ICE

     MANY RIVERS WERE ELEVATED COMING INTO THIS WEEKEND DUE TO
     FREEZE-UP ICE JAMS. IT IS DIFFICULT TO DETERMINE THE
     EFFECTS OF THAT ICE ON THE RATING CURVE DURING THE RISE.

     WE HAVE ALSO SEEN SOME RIVER GAGES SPIKE UP AS BREAK-UP
     ICE JAMS FORM AND RELEASE.  WE MUST BE CAREFUL NOT TO ROUTE
     THAT SPIKE DOWNSTREAM BECAUSE IT IS NOT A TRUE
     REPRESENTATION OF THE FLOW HYDROGRAPH.

   - COLD TEMPERATURE FORECAST

     AIR TEMPERATURES ARE FORECAST TO DROP SIGNIFICANTLY DURING
     THE NEXT FEW DAYS.  THE SUB-FREEZING TEMPERTURES MAY FREEZE
     RUNOFF EN ROUTE TO THE RIVERS CAUSING RIVER LEVELS TO DROP
     MORE QUICKLY THAN EXPECTED.

     CONVERSELY.. AT LOCATIONS PRONE TO FREEZE-UP ICE JAMS..
     RIVER LEVELS MAY RISE HIGHER THAN EXPECTED AS THE COLD
     TEMPERTURES AND RELATIVELY HIGH STREAMFLOWS CAN COMBINE TO
     FORM FREEZE-UP ICE JAMS.


FOR ADDITIONAL AND MORE IN-DEPTH INFORMATION CONCERNING RIVER
FORECASTS...PRECIPITATION AND ALL HYDROMETEOROLOGICAL INFORMATION
IN THE NCRFC AREA OF RESPONSIBILITY...PLEASE REFER TO THE NCRFC
WEB PAGE AT:     HTTP://WWW.WEATHER.GOV/NCRFC

EMERGENCY CALL BACK LIST: RJW .. SDB .. BAC .. JCH

IF NO RESPONSE FROM THIS LIST... CALL THE DOH...SCH OR HIC.


$$

...JCH/BAC...





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