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Top 5 Weather Events of 2011 across the North Country
Main 5 4 3 2 1

#5: Weather Event of 2011:April 26th-27th Flooding
On April 26th the combination of much above normal temperatures, record snow melt in the mountains, and several lines of showers and thunderstorms caused major flooding across northern New York into central and northern Vermont. Numerous roads from Essex County, New York to Essex County, Vermont were closed due to flooding, with several reports of bridges being washed away. The total damage caused by the flooding in Vermont was 6 million dollars, while figures in Essex County, New York were near 4.5 million dollars.
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Figure 31 shows a surface map on 26 April 2011 at 2100 UTC, along with a composite radar image. This clearly shows several areas of low pressure along a surface warm front, which was draped across the North Country, along with periods of showers and embedded thunderstorms.

Temperatures on the 26th and 27th were well into the 50s and 60s across the region, which helped in thunderstorm development and caused rapid snow melt in the mountains, leading to this widespread flooding event.
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Figure 32 shows the 24 hour storm total precipitation across northern New York into Vermont, with many areas receiving 1 to 3 inches of rainfall. The heaviest amounts were from the High Peaks of Essex County, New York into central Lamoille County, Vermont.
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Meanwhile, Figure 33 shows a 6 hour composite radar loop across the region, with numerous lines of showers with embedded thunderstorms impacting the North Country. The white crosses in figure 33 below indicate lightning, while the brighter oranges and reds show areas of moderate to heavy rainfall, with very high rainfall rates.
This heavy rainfall and abundant snowmelt caused widespread river flooding to occur with The Lamoille River at Johnson, Vermont recording its 4th highest level of 16.97 feet on the morning of April 27th. Figure 34 below shows the hydro-graph of the Lamoille River at Johnson, Vermont from April 25th through April 30th. The peak of 16.97 feet was above major flood stage and caused significant flooding, per figure 35 showing the Grand Union in Johnson, Vermont on April 27th.

Overall, snowmelt from an above normal snowpack and daytime high temperatures in the 50s and 60s, combined with very rainfall to produce a significant flood event across the region. Late in the day on the 26th into the early morning hours of the 27th thunderstorms repeatedly moved over the North Country, dumping additional heavy rainfall on already saturated soils and swollen rivers and streams. Flash flooding during the overnight hours late on the 26th quickly transitioned into river flooding by the morning of April 27.
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#4 >>>
Figure 31: Surface map with composite radar on 26 April 2011 at 2100 UTC.
Figure 32: 24 Hour storm total precipitation from 26 April at 1200 UTC until 27 April 2011 at 1200 UTC
Figure 33: Composite radar with lightning (white crosses) from 27 April at 00 UTC to 27 April 2011 at 06 UTC
Figure 34a: Lamoille River at Johnson river gage from 25 April to 30 April 2011
Figure 34b: River flooding in Johnson, Vermont on 27 April 2011.


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