Transcript IvarsTalk.ppt

What
Destroyed
Ivar’s
Mukilteo
Landing
Restaurant?
Ivar’s Mukilteo Landing
Restaurant was destroyed by
large waves
October 28,
2003
The“rogue wave” theory
But what was the REAL cause?
• Rogue wave?
• Intense thunderstorm with
lightning?
• Surge of winds down the
Strait?
• Tsunami?
• Powerful Pacific Storm?
• Ferry wake?
The Answer:
A surge of westerly
winds down the
Strait of Juan De
Fuca
Or as some of us like to call it:
A STRAIT WIND SURGE
Early Visitors to the Region
Learned Quickly About the
Dangers of the Strait
Strait Dangers
• During the winter, with higher pressure
inland and a low center approaching the
coast, air can accelerate to the west
producing easterly powerful winds, reaching
60-80 mph near Tatoosh Island.
Basic idea: Air accelerates from
high to low pressure in a gap
between two mountain barriers
Some people called it “the
graveyard of the Pacific”
During the days of sail, 1830 1925, 137 major shipping
tragedies occurred in the
immediate vicinity of the entrance
to the Straits of Juan de Fuca
Think of the Strait As Being A
Big Muzzle
But sometimes, under the right
conditions, the muzzle can be
turned around, now being aimed
at the eastern Strait of Juan de
Fuca and the adjacent coast
Under these conditions, Whidbey
Island, Everett, and Mukilteo can be
hit by fierce winds of hurricane
force.
Ground zero of such Strait Surges
is Everett Harbor --the location of
the newest Navy carrier base on
the West Coast!
It has happened many times in
the past
December 17, 1990: The Elwha Surge
Washington State Ferry Elwha
The Elwha Surge
• Winds were particularly severe in Everett Harbor,
where some ship anemometers measured 70-80 mph
winds.
• The Washington State ferry Elwha was thrown against
the pier by increasing wave action, destroying a
wooden barrier and snapping off pilings.
• Subsequently, the ferry beat against a concrete pier
until the vessel’s car deck crumbled.
December 17, 1990
Seattle Times and The Snohomish County Daily Herald
The event was
so noteworthy
(141,000 lost
power!) that
the local utility
district even
published a
newspaper
about it.
On October 28,
2003 another
major Strait
Surge occurred
We call it “The
Ivar’s Storm”
To get a good Westerly Strait
Surge you need three ingredients
• A strong upper level trough of low pressure
with intense northwesterly winds aligned
down the Strait aloft. We had that.
• A strong front with a big pressure rise
behind it. We had that.
• Pressure falls between the Olympics and
Vancouver Island as the air sinks down
those barriers. We had that.
October 28, 2003 4 PM
Sea Level Pressure, 4 PM October 28, 2003
Winds Gusted to 50-70 mph in
and near the Strait for 6-9 hours
Computer models correctly forecast
the winds.
UW MM5 24-h forecast
The strong winds, even with a
limited fetch, where able to
produce the wave action that
destroyed the restaurant
Today, newly installed weather sensors allow
restaurant patrons to see when active weather
is affecting the location and can head to this
restaurant to experience it.
The End