1. A Multi-Scale Analysis of the Perfect Storms of 1991 Jason M. Cordeira and Lance F. Bosart Department of Earth and Atmospheric Sciences, University at Albany, Albany, NY NROW VIII 1-2 November, 2006 cordeira@atmos.albany.edu Supported by: NSF Grant ATM-0304254

2. Perfect Storm Two (PS2) Perfect Storm One (PS1) Hurricane Grace (G) H H 1051 1044 A A A Z Z Z heavy snow cold coastal flooding and waves What were the Perfect Storms?

3. Large-scale regime transition associated with extreme weather phenomena. Large-scale regime transition associated with extreme weather phenomena. Perfect Storm One (PS1) Perfect Storm One (PS1) –Extratropical transition of Hurricane Grace. –Rapid deepening of PS1. –Tropical Transition. Perfect Storm Two (PS2) Perfect Storm Two (PS2) –Track and intensity. –Heavy snow and cold temperatures. Historical Impact… Historical Impact… Why Study the Perfect Storms?

4. Historical Impact: PS1 Coastal flooding and high winds from Canada to Puerto Rico. Coastal flooding and high winds from Canada to Puerto Rico. –67 kt at Chatham, MA. –55 kt at Blue Hill Observatory. –30 m waves SE of Nova Scotia. –8 m waves offshore MA.

5. 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. –Daily and monthly snowfall records. –Earliest temperature below 0 °F (-18 °C) in Minneapolis, MN. Historical Impact: PS2 Duluth Minneapolis

6. Large-scale flow regime Large-scale flow regime Synoptic overview Synoptic overview –250 hPa heights and winds –500 hPa heights and absolute vorticity –MSLP and 1000-500 hPa Thickness –Backward trajectories (Lagrangian) –Two cross sections of PS1 and PS2 »Theta, Potential Vorticity (PV), Omega, and Winds Results Results Future direction Future direction Outline

7. PS1 PS2 Large-scale flow regime lowest Oct. PNA index in 57 years largest Oct. positive to negative transition in 57 years

8. 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 Nov 500 hPa60 Day 01-Oct 30-Oct 30-Nov 01-Oct 30-Oct 30-Nov

9. 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 Nov 850 hPa 01-Oct 30-Oct 30-Nov 01-Oct 30-Oct 30-Nov

10. 250 hPa Heights/WindsSynoptic Overview G 29/12Z 1

11. 250 hPa Heights/WindsSynoptic Overview 30/00Z 1

12. 250 hPa Heights/WindsSynoptic Overview 30/12Z 1 2

13. 250 hPa Heights/WindsSynoptic Overview 31/00Z 1 2

14. 250 hPa Heights/WindsSynoptic Overview 31/12Z 1 2

15. 250 hPa Heights/WindsSynoptic Overview 01/00Z 1 2

16. 250 hPa Heights/WindsSynoptic Overview 01/12Z 1 2

17. 250 hPa Heights/WindsSynoptic Overview 02/00Z 1 2

18. 250 hPa Heights/WindsSynoptic Overview 02/12Z 1 2

19. 250 hPa Heights/WindsSynoptic Overview 03/00Z 2 1

20. Synoptic Overview G 29/12Z 1 12 16 20 24 28 32 500 hPa Heights & Absolute Vorticity

21. Synoptic Overview 30/00Z 1 12 16 20 24 28 32 500 hPa Heights & Absolute Vorticity

22. Synoptic Overview 30/12Z 1 2 12 16 20 24 28 32 500 hPa Heights & Absolute Vorticity

23. Synoptic Overview 31/00Z 1 2 12 16 20 24 28 32 500 hPa Heights & Absolute Vorticity

24. Synoptic Overview 31/12Z 1 2 12 16 20 24 28 32 500 hPa Heights & Absolute Vorticity

25. Synoptic Overview 01/00Z 1 2 12 16 20 24 28 32 500 hPa Heights & Absolute Vorticity

26. Synoptic Overview 01/12Z 1 2 12 16 20 24 28 32 500 hPa Heights & Absolute Vorticity

27. Synoptic Overview 02/00Z 1 2 12 16 20 24 28 32 500 hPa Heights & Absolute Vorticity

28. Synoptic Overview 02/12Z 1 2 12 16 20 24 28 32 500 hPa Heights & Absolute Vorticity

29. Synoptic Overview 03/00Z 2 12 16 20 24 28 32 500 hPa Heights & Absolute Vorticity 1

30. Synoptic Overview 29/12Z MSLP & 1000-500 hPa Thickness G 1

31. Synoptic Overview 30/00Z MSLP & 1000-500 hPa Thickness 1

32. Synoptic Overview 30/12Z MSLP & 1000-500 hPa Thickness 1

33. Synoptic Overview 31/00Z MSLP & 1000-500 hPa Thickness 1

34. Synoptic Overview 31/12Z MSLP & 1000-500 hPa Thickness 1 2

35. Synoptic Overview 01/00Z MSLP & 1000-500 hPa Thickness 1 2

36. Synoptic Overview 01/12Z MSLP & 1000-500 hPa Thickness 1 2

37. Synoptic Overview 02/00Z MSLP & 1000-500 hPa Thickness 1 2

38. Synoptic Overview 02/12Z MSLP & 1000-500 hPa Thickness 1 2

39. Synoptic Overview 03/00Z MSLP & 1000-500 hPa Thickness 1 2

40. Minimum Central Pressure (hPa) HG PS1 PS2 980 hPa 972 hPa 980 hPa 988 hPa

41. 144 h – Ending 29/12Z at 500 hPaBackward trajectories Z 500 A 900 A 300

42. 144 h – Ending 30/00Z at 300 hPaBackward trajectories Z 300 A 900

43. 144 h – Ending 02/00Z at 500 hPaBackward trajectories Z 500 A 900 A 300

44. 144 h – Ending 03/00Z at 500 hPaBackward trajectories Z 500 A 600 A 900

45. Cross-Sections: ω (dashed/μ s -1 ), PV (blue/PVU), θ (red/K), Wind (kts) 30/1200 UTC WE PS1 1 θ on the DT (2.0 PVU) μ s -1 PVUK

46. NWSE PS2 02/0000 UTC 2 θ on the DT (2.0 PVU) μ s -1 PVUK Cross-Sections: ω (dashed/μ s -1 ), PV (blue/PVU), θ (red/K), Wind (kts)

47. Downstream development produces trough that interacts with Hurricane Grace and aids in forming PS1. Downstream development produces trough that interacts with Hurricane Grace and aids in forming PS1. High pressure (1044 hPa) in SE Canada induces strong pressure gradient and strong winds. High pressure (1044 hPa) in SE Canada induces strong pressure gradient and strong winds. PS1 retrogrades and loops as upstream ridge folds over and reforms downstream in the North Atlantic. PS1 retrogrades and loops as upstream ridge folds over and reforms downstream in the North Atlantic. PS2 forms in W. Gulf of Mexico and tracks north with a deepening and negatively tilted trough. PS2 forms in W. Gulf of Mexico and tracks north with a deepening and negatively tilted trough. Strong high pressure (1051 hPa) behind PS2 ushers unseasonably cold temperatures. Strong high pressure (1051 hPa) behind PS2 ushers unseasonably cold temperatures. Synoptic Review

48. Synoptic Review (cont’d) Cross sections reveal relatively low DT (~500 hPa) with coupled regions of ascent/descent about the PV anomaly. Cross sections reveal relatively low DT (~500 hPa) with coupled regions of ascent/descent about the PV anomaly. PS2: Maximum ascent located above regions of low-level PV and low-level cold air in MN and WS. PS2: Maximum ascent located above regions of low-level PV and low-level cold air in MN and WS. What role did the cyclonic PV anomalies play in cyclogenesis? What role did the cyclonic PV anomalies play in cyclogenesis? –Hoskins 1985 suggests a positive feedback mechanism between an upper-level PV anomaly and a surface baroclinic zone that induces surface cyclogenesis.

49. Future Work Further detail into the potential vorticity perspective of the two Perfect Storms. Further detail into the potential vorticity perspective of the two Perfect Storms. Linking weather and intraseasonal climate with the Perfect Storms Linking weather and intraseasonal climate with the Perfect Storms –E.g. What role did two extratropical transitioning typhoons in the NW Pacific play in preconditioning the large-scale regime of the NH? More and not limited to… More and not limited to… –Detailed surface and satellite analyses (including marine observations!) –The role of oceanic heat fluxes –Etc. cordeira@atmos.albany.edu

50. Extras 

51. 29/12Z 1 G Theta/Winds on the DT (2.0 PVU)

52. 30/00Z 1 Theta/Winds on the DT (2.0 PVU)

53. 30/12Z 1 Theta/Winds on the DT (2.0 PVU)

54. 31/00Z 1 2 Theta/Winds on the DT (2.0 PVU)

55. 31/12Z 1 2 Theta/Winds on the DT (2.0 PVU)

56. 01/00Z 1 2 Theta/Winds on the DT (2.0 PVU)

57. 01/12Z 1 2 Theta/Winds on the DT (2.0 PVU)

58. 02/00Z 1 2 Theta/Winds on the DT (2.0 PVU)

59. 02/12Z 1 2 Theta/Winds on the DT (2.0 PVU)

60. 03/00Z 2 Theta/Winds on the DT (2.0 PVU)