Public Information Statement
Issued by NWS Binghamton, NY

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Public Information Statement
National Weather Service Binghamton NY
800 AM EST AM EST Thu Nov 9 2017

...This week is 2017 Winter Weather Awareness Week for
Pennsylvania...

The National Weather Service will feature a different educational
topic each day this week. Today`s topic is Flooding and Ice Jams.

One of our deadliest winter weather hazards is flooding.

In the state of Pennsylvania one usually associates snow, ice,
and bitter cold with winter. But sometimes nature throws a
curve at us with unseasonably warm temperatures, and heavy rain.

A number of different factors work together to produce floods
in winter.

When unseasonable warmth comes to the region it will often
melt much, if not all of the snow on the ground especially in the
lower elevations. The melting snow can saturate the ground and also
swell the rivers. If the combination of unseasonably warm
temperatures, heavy rain, and snow melt occurs, rivers may
rise above their banks producing floods.

Some of our worst winter floods are created by an intense low
pressure system that tracks from the Ohio valley northeast, down the
Saint Lawrence Valley in Canada. These storms bring a lot of warm
and moist air into the region from the Gulf of Mexico and the
Atlantic.

Flooding during the winter months can also be caused by ice
jams. When river flows increase, water levels rise. Ice is less
dense than water, thus ice floats. When enough pressure is applied
by the river below, the ice will break. Ice typically breaks into
slabs and floats downstream. When the ice interacts with an
obstruction such as a bridge, bend in the river, island, or a wide
shallow area, the ice will often pile up into an ice jam. The ice jam
then prevents water from freely flowing, and forces the water to
rise, creating a flood. Ice jams can form any time during the winter
season.

Flooding on roads and poor drainage areas can also occur when
mounds of plowed snow and ice block grates and storm drains.
Standing water can cause dangerous black ice if it freezes.

The last topic of this week will be covered tomorrow:

Friday: National Weather Service Winter Products.

Additional information will be disseminated by social media
platforms: Facebook at, http://www.facebook.com/nwsbinghamton and
Twitter at, http://www.twitter.com/nwsbinghamton

Please join us by using the following hashtags:
#Winterprep, #Winter, and #AreYouReady.

For additional information on Pennsylvania Winter Weather
Awareness Week:

http://weather.gov/bgm/wwaw

You can also contact Dave Nicosia at, david.nicosia@noaa.gov,
for additional information about 2017 Pennsylvania Winter Weather
Awareness Week.

$$

David Nicosia
Warning Coordination Meteorologist
National Weather Service Binghamton, NY




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