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Spring Flood Potential Less in the South, Near Normal in the North
March 1, 2012
AUGUSTA, MAINE — With below-normal snowpack in western and southern Maine and lesser river ice than is normal, flood potential in southern Maine is below normal for the time of year. In northern areas, however, risk factors are in the normal range. The Maine River Flow Advisory Commission, meeting today in Augusta, reviewed information on current hydrologic conditions across the state, as well as short-term weather forecasts.
Robert Lent, District Chief of the USGS Maine Water Science Center and co-chair of the Commission noted that with today’s snow storm bringing multiple inches of snow to central and southern sections, next week’s snow survey, for example, will look much different.
In addition, the National Weather Service is forecasting a fast-track rain event for the weekend, followed by cold temperatures for the start of the week. By mid-week, however, much of Maine may experience above normal temperatures, possibly for a week or more.
“Today’s conditions are a snapshot for today. Today’s storm, and the predicted warm-up show how changeable the flood potential can be, week to week and day to day, “Lent said.
The most important factor influencing flooding is rainfall. Significant rain can cause flooding even though other risk factors (snowpack, river ice and stream flows) are normal or below for the time of year.
Everyone should stay aware of current forecasts, according to Rob McAleer, Director of the Maine Emergency Management Agency, and co-chair of the Commission. “This has been a strange fall and winter, in terms of snowfall and temperature. But one rainstorm at the wrong time could still cause flooding.” McAleer noted that this year is the 25th anniversary of the flood of 1987. In that year, the snowpack was not out of the ordinary, but copious rainfall caused record catastrophic flooding.
McAleer said it is most important to check your flood insurance coverage if you live or have a business in a flood-prone area. “Most home and business owner’s policies do not cover flood damages. And there is 30-day waiting period before a new policy goes into effect,” he said. “The time to check your insurance is now.”
Snowpack water content ranged from 5 to 7 inches in far northern Maine, to just 1 to 2 inched in southern and coastal sections. Currently, the snowpack in the north is quite dry, and can absorb some amount of rainfall. These levels put water content in lowest 25% of recorded data across much of the state compared to historical averages, with a swath from Bangor west to the mountains in the lowest 10% of historic averages. However, far northern Maine water content is in the normal range. Maine Cooperative Snow Survey maps are available at http://www.maine.gov/rfac/rfac_snow.shtml
River ice is well below normal in southern Maine, but closer to normal for the time of year in the north. Rivers in the extreme southern part of the State have little to no ice. The US Coast Guard is working with the USGS to assess the need to break ice in the lower Kennebec River, downstream from Gardiner. A decision will be made in the next few days whether ice-breaking will be needed; if so, a schedule will be announced.
Stream flows likewise are normal for the time of year. Rain from Hurricane Irene brought flows sharply up in last August. However, since then streams have come back to near normal flows everywhere in the state. Reservoir storages in the headwaters of Maine’s large rivers are being drawn down to prepare for spring rains and runoff. River basin managers report that they are on track to achieve their drawdown targets.
Commission members will stay in close communication throughout the spring season, and will meet again if conditions warrant. Snow surveys will be conducted each week from now until the snow cover is gone.
The River Flow Advisory Commission meets annually in late winter to share information, examine potential for spring flooding and to renew operational protocols. The Commission is composed of state, federal and industry representatives with an interest in hydrologic issues. The full report of the March 1 meeting will be available on the Internet at http://www.maine.gov/rfac