Spring Flood Potential Below Normal in all but Northern Maine
March 3, 2016
The Maine River Flow Advisory Commission has determined that there is a below average chance of flooding this spring in most parts of the state with a normal chance in northern areas that still contain a lot of ice and snow.
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.
Snow surveys conducted this week showed snowpack water content an average of 2 1/2 inches of water across the state, where there is snow. These levels put water content in the lowest 10% to 25% of the last 10 years throughout Maine.
Snow densities average around 30% across the state areas that have snow and are expected to increase over the next few weeks as above average temperatures are forecast. Snow survey maps are available at http://maine.gov/rfac/rfac_snow.shtml
The National Weather Service noted that for the next two weeks, temperatures are expected to be above average with normal rainfall amounts. A similar pattern is expected beyond this period for the next month.
River ice is below the normal range in most areas of the State due to stream flow that is above average due to the mild winter weather. The US Coast Guard has not received requests for breakouts this year, but has spent approximately 220 hours performing ice breaking primarily in the Penobscot River but also in the Kennebec to maintain proficiency. These rivers are currently clear but cutters are standing by if ice-breaking were to become necessary.
Reservoir storages in the headwaters of Maine's large rivers are being maintained greater than 20% above average to compensate for current ice and snow conditions due to our mild winter. River basin managers report that rain and snow melt can be adequately handled this spring.
The most important factor influencing flooding is rainfall, but any snowpack adds risk. When water in the snowpack is released suddenly, by rainfall and warm temperatures, runoff amounts are increased dramatically. Careful weather monitoring is particularly important at this time of year.
Significant ice in rivers and streams presents an additional risk that cannot be forecast. Ice can jam, and water behind the jam can rise several feet in just a few minutes as we saw in Augusta earlier this year. When an ice jam lets go, water levels downstream rise suddenly.
The annual meeting of the Commission represents the beginning of "flood season" in Maine, when all parties focus close attention to risk factors for flooding, and to temperature and precipitation forecasts. The following steps are recommended:
- Check your flood insurance coverage if your home or business is 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.
- If you live or work in a flood-prone area, pay close attention to conditions in the next several weeks. Be aware that any sudden warm-up or significant rainstorm in the late winter and early spring carries the risk of flooding.
- If you live along a river or stream, watch for signs of ice jams. Signs include ice piling up and appearing to block the channel, coupled with rising water levels behind the jam. Report any suspected ice jams to local officials or the National Weather Service.
Commission members will stay in close communication throughout the spring season. 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 3 meeting will be available online at http://www.maine.gov/rfac by close of business on March 4.