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MEMA Home > Programs> Communication> News > Flood Potential Remains High as Spring Drags Its Heels

Flood Potential Remains High as Spring Drags Its Heels

 

April 2, 2014

 

Spring flood potential remains high in much of the State, as snow and ice persist across the foothills, mountains and north, including the headwaters of Maine's major rivers.

The Maine River Flow Advisory Commission hosted a conference call today to review current hydrologic conditions. This was a follow-up to the Commission's meeting on March 6.

Snow Survey

The Maine Cooperative Snow Survey measured the snowpack at almost one hundred sites this week. Snowpack depth and water content increased in many areas after last week's storm.

There is 9 to 12 inches of water in the snow in a belt across the north central area of the state, encompassing the headwaters of most of Maine's major rivers. In Aroostook County, there are 6 to 10 inches of water in the snow. Water content held steady or increased over last week's measurements. Water content is in the upper 25% to upper 10% of historical values for the time of year.

Snow densities (the relative amount of water in the snow) ranged from .40 in a few locations in the south to less than .20 in the far north. The relative "dryness" of the snow in the north is very unusual for the time of year, with density readings 2 to 3 weeks behind where they would normally be at this time of year. (A snowpack with densities above 0.33 is considered "ripe". A ripe snowpack no longer has the ability to absorb rainfall and would tend to release water during a rain event.)

Snow surveys will be conducted weekly until all the snow is gone.

Stream Flow and Ice Conditions

Stream flows remain low for the time of year. Rivers and streams generally increase in early March as snowmelt begins. This year, this "turn" in stream flow levels has been delayed for at least two weeks in central to southern sections and is just now beginning to be seen in the these areas. Gradually increasing stream flows in the spring are a major factor in eroding ice cover gradually.

Ice jamming remains a concern in central and northern Maine, where rivers and tributaries still are carrying a significant ice cover. In some areas of the far north, this is as much of 1.5 to 2 feet of strong black ice.

NWS Caribou will be monitoring river ice from the ground this week, and overflights of the St. John River to assess ice conditions are being planned. Overflights this week of the Kennebec and Penobscot Rivers showed ice erosion beginning south of Bangor and Augusta. The US Coast Guard completed their mission of ice breaking from Bath to Gardiner on the Kennebec last week, which frees up a path in the lower river for ice coming from upstream.

Weather Outlook

According to the National Weather Service forecast offices in Gray and Caribou, weather conditions in the next two weeks may actually add to the water content in the headwaters and northern regions. Temperatures, though below normal, will be above freezing during the day, and cooler at night, which is desirable for melting snow and eroding ice gradually. However, two precipitation events are expected for Saturday and Monday into Tuesday, which will bring rain to the south and mixed precipitation farther north, likely adding to the water content in the snow.

Flood Potential

Flooding in Maine does not generally occur from snowmelt alone; rain is the primary factor. However, as spring progresses, the probability for major rainstorms and warm temperatures increases. The significant snowpack and river ice greatly add to the risk factors for flooding. Therefore, flood potential across the state remains high.

Both Weather Service offices issue Flood Potential Statements every two weeks during the spring. The next statements will be published this week.

The River Flow Advisory Commission will likely convene again later in April to assess conditions across the State.

 

 

Last update: 07/20/10