Public Information Statement
Issued by NWS Denver/Boulder, CO

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NOUS45 KBOU 191640

1040 AM MDT WED OCT 19 2016

Widespread high winds visit Colorado during the winter.

Governor John Hickenlooper has proclaimed this week through October
22nd as Winter Weather Prepareness Week in Colorado.

The two main causes of high winds in Colorado during the cold season
are the air pressure difference between strong low pressure and cold
high pressure systems, and chinook winds developing across the Front
Range and other eastern mountain ranges.

A strong, cold high pressure system moving in from the north and
setting up to the west of the Rockies can generate a damaging wind
down the leeward slopes of the mountains, known as a bora. these
episodes feature widespread high winds from the west or northwest
into the adjacent plains at speeds which can exceed 100 mph. Much
more rare are those episodes when low pressure is across the
Rockies, and strong, cold high pressure is across the Great Plains.
The result is damaging winds from the east across the western slopes
of mountain ranges and adjacent valleys.

Mid and upper level winds over Colorado are much stronger in the
winter than in the warm season, because of the huge difference in
temperature from north to south across North America.  West winds,
under certain conditions, can bring warm, dry chinook winds
cascading down the slopes of the eastern mountains. These winds can
exceed 100 mph in extreme cases, bringing the potential for
widespread damage. Winds of 60 to near 100 mph will occur in and
near the foothills in areas such as Fort Collins, Boulder, Denver,
Colorado Springs, Canon City, Westcliffe, Walsenburg and Trinidad.
The areas around Boulder and Westcliffe are especially prone to
these extreme wind episodes.

Dangers from high winds include flying debris, reduced visibility
due to dust, damaged or destroyed structures, downed power lines,
and overturned vehicles.  The National Weather Service will issue a
High Wind Watch when there is around a 50 percent chance for high
winds to develop during the next day or two. When the threat becomes
more certain in a specific area, a High Wind Warning will be issued.
Cold strong winds can also bring dangerously low wind chill values,
prompting a wind chill advisory or wind chill warning.

If high winds are forecast for your area, you should bring
lightweight objects indoors, or tie them down outdoors, or move them
so they do not become dangerous missiles.  Any downed power lines
should not be approached. Instead call the utility company.
Stay clear from buildings under construction during high winds, as
they can easily collapse. Traveling on north south roads near the
mountains along the Front Range during a high wind episode can also
be dangerous.  If you drive a lightweight or high profile vehicle,
you may want to wait until the high winds die down.

Tom Magnuson
Warning Coordination Meteorologist
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