Flood — Cumberland, Maine

2007-04-16 to 2007-04-18 · near Portland, Cumberland, Maine

Event narrative

Flooding and damages were countywide.

Wider weather episode

An area of low pressure over the southeastern United States on the morning of Sunday, April 15th, rapidly intensified as it slowly moved north to near New York City by the morning of Monday, April 16th. This intense low in combination with high pressure over eastern Canada produced Overview: An area of low pressure intensified rapidly as it moved slowly from the southeastern United States on the morning of Sunday, April 15th to near New York City by the morning of Monday, April 16th. The intense low over New York City in combination with high pressure over eastern Canada produced a very intense pressure gradient across the area which caused strong east to northeast winds to develop across the region. Over land, the strong winds downed numerous trees. The downed trees caused widespread power outages, especially near the coast, and numerous road closures. Over the marine areas, the strong winds caused a storm surge and large ocean waves of up to 30 feet to develop. The combination of astronomical high tides, storm surge, and large waves contributed to coastal flooding in coastal areas of the state and severe coastal erosion in areas south of Portland.

The storm also brought heavy rain to the region which, when combined with snow melt, produced widespread flooding across much of the region. The flooding of small rivers and streams was worst in southern and coastal areas and led to numerous road closures. In the mountains, the rain was preceded by heavy snow. Flooding was minor on most mainstem rivers, however, in southern Maine, the Presumpscot River reached near record levels.

The intense low drifted very slowly eastward from Monday morning through Friday morning as it gradually weakened. During this time, the pressure gradient slowly relaxed, the winds gradually diminished, and the seas slowly subsided. However, rain continued into Tuesday across the region and each high tide during the period brought a reoccurrence of coastal flooding and erosion to the area. Power outages persisted, and stream and river flooding continued across the region during this period. Many roads remained closed.

On Friday, April 20, high pressure built eastward from the Great Lakes ending the influence of the Atlantic storm.

Wind: The pressure gradient associated with the storm brought high winds to the region. The damage observed in the hardest hit areas was typical of wind gusts of 60 to 80 mph. While most observing sites reported winds below this range, topography, elevation, and exposure were likely factors in determining the amount of wind damage any location experienced. In addition, the heavy rain brought strong wind gusts to the ground level and contributed to the sporadic nature of the heaviest wind damage. In addition to the meteorological factors, damage from the wind was exacerbated because of the heavy rain that accompanied the wind and the soft, wet ground caused by the spring thaw.

The wind knocked over numerous trees and branches throughout the region and caused numerous and prolonged power outages throughout the region.

Coastal Flooding/Storm Surge/Waves: The coastal storm hit during a period of very high (and very low) astronomical tides. In addition to the astronomical tides, the prolonged period of strong northeast winds caused a prolonged storm surge along the coastline. Also during this period, the strong winds caused large and battering waves along the coast. The storm tides and large waves caused significant flooding and coastal erosion.

In Portland, flood level is 12 feet. During the storm, storm tides reached or exceeded the 12 foot flood level during 7 tidal cycles. In addition, due to the large waves, coastal erosion occurred throughout the week of April 15th to 20th when the Portland gauge was above or near the 12 foot flood level. Communication was lost with NOAA's Portland Weather Buoy shortly after 6 am Monday when it was reporting 31 foot seas.

Precipitation: Rain developed across the southern part of the state early Sunday afternoon, April 15th and spread northward. The rain became heavy during the afternoon and overnight. By Monday morning, 3 to 7 inches of rain had fallen in York County with rainfall amounts decreasing to 1 to 4 inches to the north and east. In the mountains of Maine, 2 to 7 inches of snow fell by Monday morning. Although the heaviest precipitation fell from Sunday afternoon into Monday afternoon, precipitation persisted into Tuesday. Rainfall in Southern Maine was near the 100 year recurrence interval at Sanford and Eliot.

Flooding: The heavy rain combined with snow melt to cause flooding of small rivers and streams in much of southern and central Maine. The worst flooding occurred on the smaller rivers in York County. Damage to infrastructure was severe (roads, bridges, waste water treatment plants, public buildings). Homes and businesses were also damaged. In York County, two people were killed when they attempted to cross a flooded road on foot and were swepted away. The crest on the Presumpscot River was just below the crest recorded during Hurricane Bob in August of 1991.

View location on OpenStreetMap → (43.6700, -70.2700)

Source: NOAA Storm Events Database, event_id 30071. Narrative written by the NWS forecast office that issued the report.