A Multi-Scale Analysis of the Perfect Storms of 1991

A Multi-Scale Analysis A Multi-Scale Analysis of the of the Perfect StormsPerfect Storms

of 1991of 1991

Jason M. Cordeira and Lance F. BosartJason M. Cordeira and Lance F. BosartDepartment of Earth and Atmospheric Sciences, University at Albany, Albany, NYDepartment of Earth and Atmospheric Sciences, University at Albany, Albany, NY

NROW VIII 1-2 November, 2006

[email protected]

Supported by:NSF Grant ATM-0304254

Perfect Storm Two

(PS2)

Perfect Storm One

(PS1)

Hurricane Grace (G)

HH1051

1044

A

AA

Z

Z

Z

heavy snowcold

coas

tal f

lood

ing

and

wav

es

What were the Perfect Storms?

Large-scale regime transition associated with extreme Large-scale regime transition associated with extreme weather phenomena.weather phenomena.

Perfect Storm One (PS1)Perfect Storm One (PS1)– Extratropical transition of Hurricane Grace.Extratropical transition of Hurricane Grace.– Rapid deepening of PS1.Rapid deepening of PS1.– Tropical Transition.Tropical Transition.

Perfect Storm Two (PS2)Perfect Storm Two (PS2)– Track and intensity.Track and intensity.– Heavy snow and cold temperatures.Heavy snow and cold temperatures.

Historical Impact…Historical Impact…

Why Study the Perfect Storms?

Historical Impact: PS1 Coastal flooding and high winds from Canada to Puerto Coastal flooding and high winds from Canada to Puerto

Rico.Rico.– 67 kt at Chatham, MA. 67 kt at Chatham, MA. – 55 kt at Blue Hill Observatory.55 kt at Blue Hill Observatory.– 30 m waves SE of Nova Scotia. 30 m waves SE of Nova Scotia. – 8 m waves offshore MA.8 m waves offshore MA.

State record: 93.7 cm of snow in Duluth, MN.State record: 93.7 cm of snow in Duluth, MN. Other records:Other records:

– Earliest 20.0 cm snowfall.Earliest 20.0 cm snowfall.

– Daily and monthly snowfall records.Daily and monthly snowfall records.

– Earliest temperature below 0 Earliest temperature below 0 °F (-18 °C)°F (-18 °C)in Minneapolis, MN. in Minneapolis, MN.

Historical Impact: PS2

Duluth

Minneapolis

Large-scale flow regimeLarge-scale flow regime Synoptic overviewSynoptic overview

– 250 hPa heights and winds250 hPa heights and winds

– 500 hPa heights and absolute vorticity500 hPa heights and absolute vorticity

– MSLP and 1000-500 hPa ThicknessMSLP and 1000-500 hPa Thickness

– Backward trajectories (Lagrangian)Backward trajectories (Lagrangian)

– Two cross sections of PS1 and PS2Two cross sections of PS1 and PS2» Theta, Potential Vorticity (PV), Omega, and WindsTheta, Potential Vorticity (PV), Omega, and Winds

ResultsResults Future directionFuture direction

Outline

PS1PS2

Large-scale flow regime

lowest Oct. PNA index in 57 years

largest Oct. positive to negative transition in 57 years

Images provided by the NOAA/ESRL Physical Sciences Division, Boulder Colorado from their Web site at http://www.cdc.noaa.gov/.

01-Oct to 30 Nov01-Oct to 30 Nov 500 hPa60 Day

01-Oct

30-Oct

30-Nov

01-Oct

30-Oct

30-Nov

Images provided by the NOAA/ESRL Physical Sciences Division, Boulder Colorado from their Web site at http://www.cdc.noaa.gov/.

01-Oct to 30 Nov01-Oct to 30 Nov 850 hPa

01-Oct

30-Oct

30-Nov

01-Oct

30-Oct

30-Nov

250 hPa Heights/Winds Synoptic Overview

G

29/12Z

1


30/00Z

1


30/12Z

12


31/00Z

1

2


31/12Z

12


01/00Z

12


01/12Z

12


02/00Z

12


02/12Z

12


03/00Z

2 1

Synoptic Overview

G

29/12Z

1

12 16 20 24 28 32

500 hPa Heights & Absolute Vorticity

Synoptic Overview

30/00Z

1

12 16 20 24 28 32


Synoptic Overview

30/12Z

12

12 16 20 24 28 32


Synoptic Overview

31/00Z

1

2

12 16 20 24 28 32


Synoptic Overview

31/12Z

12

12 16 20 24 28 32


Synoptic Overview

01/00Z

12

12 16 20 24 28 32


Synoptic Overview

01/12Z

12

12 16 20 24 28 32


Synoptic Overview

02/00Z

12

12 16 20 24 28 32


Synoptic Overview

02/12Z

12

12 16 20 24 28 32


Synoptic Overview

03/00Z

2

12 16 20 24 28 32


1

Synoptic Overview

29/12Z

MSLP & 1000-500 hPa Thickness

G

1

Synoptic Overview

30/00Z


1

Synoptic Overview

30/12Z


1

Synoptic Overview

31/00Z


1

Synoptic Overview

31/12Z


1

2

Synoptic Overview

01/00Z


12

Synoptic Overview

01/12Z


12

Synoptic Overview

02/00Z


1

2

Synoptic Overview

02/12Z


12

Synoptic Overview

03/00Z


12

Minimum Central Pressure (hPa)

HG

PS1

PS2

980 hPa

972 hPa

980 hPa

988 hPa

144 h – Ending 29/12Z at 500 hPaBackward trajectories

Z500

A900

A300


Z300

A900


Z500

A900

A300


Z500

A600A900

Cross-Sections: ω (dashed/μ s-1), PV(blue/PVU), θ (red/K), Wind (kts)

30/1200 UTC

W E

PS1

1

θ on the DT (2.0 PVU)

μ s-1 PVU K

NW SE

PS202/0000 UTC

2

θ on the DT (2.0 PVU)

μ s-1 PVU K

Cross-Sections: ω (dashed/μ s-1), PV(blue/PVU), θ (red/K), Wind (kts)

Downstream development produces trough that interacts Downstream development produces trough that interacts with Hurricane Grace and aids in forming PS1.with Hurricane Grace and aids in forming PS1.

High pressure (1044 hPa) in SE Canada induces strong High pressure (1044 hPa) in SE Canada induces strong pressure gradient and strong winds.pressure gradient and strong winds.

PS1 retrogrades and loops as upstream ridge folds over PS1 retrogrades and loops as upstream ridge folds over and reforms downstream in the North Atlantic.and reforms downstream in the North Atlantic.

PS2 forms in W. Gulf of Mexico and tracks north with a PS2 forms in W. Gulf of Mexico and tracks north with a deepening and negatively tilted trough.deepening and negatively tilted trough.

Strong high pressure (1051 hPa) behind PS2 ushers Strong high pressure (1051 hPa) behind PS2 ushers unseasonably cold temperatures.unseasonably cold temperatures.

Synoptic Review

Synoptic Review (cont’d)

Cross sections reveal relatively low DT (~500 Cross sections reveal relatively low DT (~500 hPa) with coupled regions of ascent/descent about hPa) with coupled regions of ascent/descent about the PV anomaly.the PV anomaly.

PS2: Maximum ascent located above regions of PS2: Maximum ascent located above regions of low-level PV and low-level cold air in MN and low-level PV and low-level cold air in MN and WS.WS.

What role did the cyclonic PV anomalies play in What role did the cyclonic PV anomalies play in cyclogenesis?cyclogenesis?– Hoskins 1985 suggests a positive feedback mechanism Hoskins 1985 suggests a positive feedback mechanism

between an upper-level PV anomaly and a surface between an upper-level PV anomaly and a surface baroclinic zone that induces surface cyclogenesis.baroclinic zone that induces surface cyclogenesis.

Future Work

Further detail into the potential vorticity perspective Further detail into the potential vorticity perspective of the two Perfect Storms.of the two Perfect Storms.

Linking weather and intraseasonal climate with the Linking weather and intraseasonal climate with the Perfect Storms Perfect Storms – E.g. What role did two extratropical transitioning E.g. What role did two extratropical transitioning

typhoons in the NW Pacific play in preconditioning the typhoons in the NW Pacific play in preconditioning the large-scale regime of the NH?large-scale regime of the NH?

More and not limited to…More and not limited to…– Detailed surface and satellite analyses (including marine Detailed surface and satellite analyses (including marine

observations!)observations!)– The role of oceanic heat fluxesThe role of oceanic heat fluxes– Etc.Etc.

[email protected]

Extras

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Theta/Winds on the DT (2.0 PVU)

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A Multi-Scale Analysis of the Perfect Storms of 1991

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