Examining the Damaging New England Windstorm of 25-26

Examining the Damaging New
England Windstorm of 25-26
February 2010 as a Shapiro-Keyser
Stacie Hanes/NOAA NWS Gray ME
Jim Hayes/NOAA NWS Mount Holly NJ
12th Northeast Regional Operational
November 3-5, 2010
• Overview of the event
• Review of the structure and evolution of a
Norwegian and a Shapiro-Keyser cyclone
• Overview of the synoptic setup prior to the
damaging winds
• Use of observational and model data to
identify the structure of Shapiro-Keyser
Brief overview of the event
• East to northeast winds
gusted as high as 94 mph
during the late evening and
overnight of 25-26 Feb 2010
• The strongest gusts
occurred with the passage
of a surface trough
• Significant damage occurred
across southeast New
Hampshire and southwest
and central Maine
This wind event caused
the second largest number
of power outages ever in
New Hampshire
Brief overview of the event
• Three peak wind gusts
of over 90 MPH were
recorded during this
• Portland ME (PWM)
had its highest wind
gust ever recorded. It
may have been higher,
but the power failed at
the ASOS
The highest wind speeds occurred with surface trough
between 1100 PM and 200 AM across southeast New
Hampshire and southern Maine.
Destructive winds from the east or northeast are fairly
rare in northern New England, especially at night.
Was this the result of a warm front/occluded frontal
passage, or something else?
Norwegian Cyclone Model
Typically the strong winds occur in the warm sector in this
cyclone model or on the back side in the cold air
Norwegian Cyclone Model
This cyclone model
could account for
stronger winds reaching
the surface in the
“warm sector”, but the
low levels appear too
stable to allow turbulent
mixing in the “cool
This model does not
explain the destructive
winds on the cold side
of the warm/occluded
Shapiro-Keyser Model
Open wave (similar to the
Norwegian cyclone model
II. Frontal fracture (T bone frontal
III. Bent-back front – strong winds
on the cold side of the warm
IV. Warm seclusion – evaporative
cooling/descent can allow an
eye-like feature to develop.
Shapiro-Keyser model
• Typically develops as a marine cyclone
• Generally forms in large scale confluence and
a high zonal index flow
• Characterized by a strong warm front, weak
cold front and T bone frontal structure
So now that we have an idea of how
the storm should look…what did the
models show?
Models were fairly close concerning the
overall sequence of events. The 1200 UTC 25
Feb 2010 NAM model solution is examined.
1200 UTC 25 Feb 2010 NAM - 0600 UTC (left) and 0900 UTC (right)
1200 UTC 25 Feb 2010 NAM - 0000 UTC (left) and 0300 UTC (right)
1200 UTC 25 Feb 2010 NAM - 0600 UTC (left) and 0900 UTC (right)
Bottom line
• The NAM was
forecasting a highly
anomalous event for
northern New England
– Many forecast
parameters showed
departures of 4 to 5
standard deviations
– Main time frame was
0300 UTC to 0900 UTC
for the forecast area
Examining the Shapiro-Keyser
cyclone environment using
observational tools
0015z 26 Feb 2010 IR image – the cyclone
is the in bent-back front stage (Stage III)
0000 UTC 26 Feb 2010 GYX
observed sounding
The depth of the mixed
later is unusual for an
easterly flow at night
0255 UTC 26 FEB 2010
AMDAR descent
sounding at BOS
60 knot wind at
1210 ft.
0415z 26 Feb 2010 IR image – the cyclone
is the in warm seclusion stage (Stage IV)
• Damaging winds occurred in northern New England
during the late evening of 25 February 2010 and the early
morning of 26 February 2010
– Damage was caused by east to northeast winds during
an unusual time
– A few locations had maximum wind gusts over 90
• PWM had its high wind gust ever before the ASOS power
• The damaging winds occurred in the cold air ahead of the
warm front, which suggests a Shapiro-Keyser cyclone

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