Sunday, March 13, 2011

Flooding update from National Weather Service

The National Weather Service in Chanhassen issued it’s latest Hydrologic Outlook for the rivers of Minnesota.  It expects flood watches and warnings to be issued by mid-week with snow melt and forecasted precipitation over the next couple weeks.  This is a sign that flood season is upon us, and for over the next month or so, will be a major story across the Upper Midwest.

HYDROLOGIC OUTLOOK NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 549 PM CDT SUN MAR 13 2011

...WARM TEMPERATURES THIS WEEK ARE EXPECTED TO INCREASE MELTING AND POTENTIALLY LEAD TO RIVER FLOODING AS EARLY AS NEXT WEEKEND...

A CHANGE IN THE WEATHER PATTERN WILL BRING WARMER TEMPERATURES TO CENTRAL AND SOUTHERN MINNESOTA AS WELL AS WEST CENTRAL WISCONSIN TUESDAY AND ESPECIALLY INTO WEDNESDAY AND THURSDAY. TEMPERATURES WILL BE IN THE LOWER AND MID 40S ON TUESDAY AND IN THE UPPER 40S AND LOWER 50S ON WEDNESDAY AND THURSDAY. HIGHS ON FRIDAY WILL BE COOLER...BUT STILL IN THE MID 30S IN WEST CENTRAL MINNESOTA TO THE LOWER AND MID 40S IN SOUTH CENTRAL MINNESOTA AND INTO WEST CENTRAL WISCONSIN.

LOWS WEDNESDAY MORNING ARE EXPECTED TO BE IN THE MID TO UPPER 20S WHICH WILL HELP SLOW THE MELTING PROCESS FROM TUESDAY. BUT FOR OVERNIGHT WEDNESDAY NIGHT AND INTO THURSDAY MORNING...TEMPERATURES ARE NOT EXPECTED TO DROP BELOW FREEZING ACROSS SOUTH CENTRAL AND EAST CENTRAL MINNESOTA. PARTS OF WEST CENTRAL WISCONSIN WILL ONLY DROP TO AROUND 40 DEGREES. LOWS FRIDAY MORNING WILL RANGE FROM THE MID 20S IN CENTRAL MINNESOTA TO THE LOWER 30S IN SOUTH CENTRAL MINNESOTA. LOWS IN WEST CENTRAL WISCONSIN WILL DROP INTO THE UPPER 20S. HENCE THE MELTING PROCESS WILL CONTINUE FROM WEDNESDAY THROUGH THURSDAY NIGHT. SO A GOOD 36 HOURS OF STRAIGHT MELTING IS LIKELY.

WE ARE ALSO LOOKING AT A COUPLE OF CHANCES OF LIGHT RAIN IN THE NEXT 7 TO 10 DAYS. THE FIRST CHANCE WILL BE ON TUESDAY. AT THIS TIME THE SYSTEM DOES NOT TAP INTO THE GULF OF MEXICO FOR A MOISTURE SOURCE...SO PRECIPITATION AMOUNTS WILL BE LIGHT AND AROUND A TENTH OF AN INCH OR LESS. ANOTHER SYSTEM WILL MOVE ACROSS THE AREA ON THURSDAY. AS WITH THE TUESDAY SYSTEM PRECIPITATION AMOUNTS ALSO LOOK LIGHT. WE ARE WATCHING ANOTHER STRONGER STORM SYSTEM FOR LATE NEXT WEEKEND AND INTO PART OF NEXT WEEK. THIS ONE MAY BE ABLE TO TAP INTO THE GULF OF MEXICO. THIS SYSTEM IS STILL AT LEAST 7 DAYS OUT IN THE FORECAST SO PATTERNS MAY CHANGE BUT IT IS WORTH WATCHING FOR A RAIN EVENT.

THE WARMING TEMPERATURES FOR THE MIDDLE PART OF THE WEEK ARE EXPECTED TO BEGIN MELTING THE SNOW. AT THIS POINT...WE ARE EXPECTING RISES IN THE MAIN STEM RIVERS BEGINNING...INTO THE LATER PART OF THE WEEK. HOW WARM WE ACTUALLY GET DURING THE DAY...AND HOW WARM WE REMAIN OVERNIGHT AS WELL AS OUR MOISTURE LEVELS AND WINDS...WILL BE THE MAIN DRIVERS FOR THE MELT.

AT THIS POINT WE COULD SEE SIGNIFICANT RISES ESPECIALLY FOR THE COTTONWOOD...REDWOOD...MINNESOTA...CROW AND MISSISSIPPI FOR ST PAUL AND DOWNSTREAM...AND THE ST CROIX RIVER BASINS OVER THE NEXT FIVE TO TEN DAYS. FOR THESE RIVER BASINS...WE COULD POSSIBLY SEE FLOOD STAGE LEVELS AS EARLY AS NEXT WEEKEND.

FOR THE LONG PRAIRE...SAUK...THE MISSISSIPPI RIVER FOR MINNEAPOLIS AND UPSTREAM...EAU CLAIRE AND CHIPPEWA RIVER IN WISCONSIN BASINS...WE ARE LOOKING FOR RISES BUT AT THIS POINT INDICATIONS ARE THAT THEY WILL REMAIN BELOW FLOOD STAGE FOR THE NEXT WEEK.

AS CONFIDENCE INCREASES ON THE MELT AND IMPACTS ON THE RIVERS...RIVER FLOOD WATCHES AND...OR WARNINGS WILL LIKELY BE ISSUED BY WEDNESDAY.

PLEASE REFERENCE THE NWS TWIN CITIES RIVER WEBSITE AT WWW.WATER.WEATHER.GOV/AHPS2/INDEX.PHP?WFO=MPX

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