1. Upper-level Mesoscale Disturbances on the Periphery of Closed Anticyclones Thomas J. Galarneau, Jr. and Lance F. Bosart University at Albany, State University of New York Albany, NY 12222 USA Fourth Symposium on Southwest Hydrometeorology 21 September 2007 – Tucson, AZ

2. Motivation Warm season continental closed anticyclones (CAs) link weather and climate on intraseasonal time scales Warm season continental closed anticyclones (CAs) link weather and climate on intraseasonal time scales Can persist for most of 90-day warm season Can persist for most of 90-day warm season Surface temperature/rainfall anomalies with CAs can determine overall seasonal anomalies for a given region Surface temperature/rainfall anomalies with CAs can determine overall seasonal anomalies for a given region High-impact severe weather on CA periphery associated with mesoscale disturbances High-impact severe weather on CA periphery associated with mesoscale disturbances

3. Goals Examine the CA of July 1995 over the US Examine the CA of July 1995 over the US Impact on rainfall distribution Impact on rainfall distribution Behavior of mesoscale disturbances on periphery of CA and their role in MCS development Behavior of mesoscale disturbances on periphery of CA and their role in MCS development

4. Data and Methods 2.5  NCEP–NCAR Reanalysis 2.5  NCEP–NCAR Reanalysis 1.125  ECMWF Reanalysis (ERA-40) 1.125  ECMWF Reanalysis (ERA-40) 0.25  NCEP Unified Precipitation Dataset (UPD) 0.25  NCEP Unified Precipitation Dataset (UPD) University of Wyoming sounding archive University of Wyoming sounding archive National Lightning Detection Network (NLDN) National Lightning Detection Network (NLDN) Dynamic tropopause defined at 1.5 PVU surface Dynamic tropopause defined at 1.5 PVU surface

5. July 1995 CA over US

6. 11-15 Jul 1995 500 hPa HGHT 500 hPa Height (dam) Mean and Anomaly and Wind (m/s) 5–10 July 1995 11–15 July 1995 Height Anomaly Wind Fig. A1 from Galarneau et al. 2007 ridge building eastward progression 2.5  NCEP–NCAR Reanalysis

7. 5 6 7 8 9 10 11 12 131415 850 hPa 21  C Isotherm Continuity Map 0000 UTC 5–15 July 1995 Fig. A5 from Galarneau et al. 2007 2.5  NCEP–NCAR Reanalysis

8. 00Z/13 DT  (K) and wind (knots) NLDN CG lightning X X X MCS #1 PV tail mesoscale disturbance 1.125  ECMWF Reanalysis +/-+/-

9. 12Z/13 DT  (K) and wind (knots) X MCS #1 PV tail mesoscale disturbance X X X X X X X X 1.125  ECMWF Reanalysis +/-+/- NLDN CG lightning

10. 00Z/14 DT  (K) and wind (knots) X MCS #1 PV tail mesoscale disturbance X X X X X X X X 1.125  ECMWF Reanalysis +/-+/- NLDN CG lightning MCS #2

11. 12Z/14 DT  (K) and wind (knots) X MCS #2 PV tail mesoscale disturbance X X X X X X X X X X 1.125  ECMWF Reanalysis +/-+/- NLDN CG lightning

12. 00Z/15 DT  (K) and wind (knots) X MCS #3 PV tail mesoscale disturbance X X X X X X X X 1.125  ECMWF Reanalysis +/-+/- NLDN CG lightning

13. 12Z/15 DT  (K) and wind (knots) X MCS #3 PV tail mesoscale disturbance X X X X X X 1.125  ECMWF Reanalysis +/-+/- NLDN CG lightning

14. H L PV Tail Strong Jet mesoscale disturbance source region Schematic for 13–15 July 1995 DT flow X X X

15. CG Lightning 12–15 July 1995 12–1313–1414–15+/- NLDN

16. Storm Reports 12–15 July 1995 MCS #1 MCS #2 MCS #3 Reports associated with PV tail tornado wind hail + Generated using SeverePlot v2.5 Source: Storm Prediction Center tornado/wind reports near persistent trough

17. 850  e (K), 925–500 wind shear (knots), 850–500 lapse rate (K km -1 ) 00Z/13–15 July 1995 1.125  ECMWF Reanalysis

18. 850  e (K), 925–500 wind shear (knots), 850–500 lapse rate (K km -1 ) 00Z/13–15 July 1995 2300 J kg -1 00Z/13 1.125  ECMWF Reanalysis Univ. Wyoming

19. 850  e (K), 925–500 wind shear (knots), 850–500 lapse rate (K km -1 ) 00Z/13–15 July 1995 7000 J kg -1 00Z/13 1.125  ECMWF Reanalysis Univ. Wyoming

20. 850  e (K), 925–500 wind shear (knots), 850–500 lapse rate (K km -1 ) 00Z/13–15 July 1995 1800 J kg -1 00Z/14 1.125  ECMWF Reanalysis Univ. Wyoming

21. % Contribution of JJA to Yearly Precipitation 1948–2003 % UPD

22. % Contribution of 12–15 Jul to JJA Climo % UPD ~25% ~20–30%

23. Case Study Summary Downstream development led to ridge building over the Intermountain West Downstream development led to ridge building over the Intermountain West As CA moved eastward, convection formed on the periphery in association with mesoscale disturbances and a PV tail As CA moved eastward, convection formed on the periphery in association with mesoscale disturbances and a PV tail Serial severe MCSs formed on poleward side Serial severe MCSs formed on poleward side High CAPE, high shear environment High CAPE, high shear environment Scattered convection formed on equatorward side Scattered convection formed on equatorward side Moderate CAPE, low-moderate shear environment Moderate CAPE, low-moderate shear environment

24. Climate Implications Rainfall Rainfall MCSs on periphery contributed ~25% of climatological JJA precipitation MCSs on periphery contributed ~25% of climatological JJA precipitation Mesoscale disturbances can produce intense rain events and/or severe weather events Mesoscale disturbances can produce intense rain events and/or severe weather events Temperature Temperature Subset of CAs that build over Intermountain West, then move eastward can produce heat waves Subset of CAs that build over Intermountain West, then move eastward can produce heat waves Climatologically hot air over Intermountain West must be displaced to “anomalous” regions Climatologically hot air over Intermountain West must be displaced to “anomalous” regions

25. Postscript: Upper-level disturbances, PV tails, and tropical systems

26. DT  (K), wind (knots), and 925–850 hPa  (10 -5 s -1 ) 06Z/16

27. DT  (K), wind (knots), and 925–850 hPa  (10 -5 s -1 ) 12Z/16

28. DT  (K), wind (knots), and 925–850 hPa  (10 -5 s -1 ) 18Z/16

29. DT  (K), wind (knots), and 925–850 hPa  (10 -5 s -1 ) 00Z/17

30. DT  (K), wind (knots), and 925–850 hPa  (10 -5 s -1 ) 06Z/17

31. DT  (K), wind (knots), and 925–850 hPa  (10 -5 s -1 ) 12Z/17

32. DT  (K), wind (knots), and 925–850 hPa  (10 -5 s -1 ) 18Z/17

33. DT  (K), wind (knots), and 925–850 hPa  (10 -5 s -1 ) 00Z/18

34. DT  (K), wind (knots), and 925–850 hPa  (10 -5 s -1 ) 06Z/18

35. DT  (K), wind (knots), and 925–850 hPa  (10 -5 s -1 ) 12Z/18

36. DT  (K), wind (knots), and 925–850 hPa  (10 -5 s -1 ) 18Z/18

37. DT  (K), wind (knots), and 925–850 hPa  (10 -5 s -1 ) 00Z/19

38. DT  (K), wind (knots), and 925–850 hPa  (10 -5 s -1 ) 06Z/19

39. DT  (K), wind (knots), and 925–850 hPa  (10 -5 s -1 ) 12Z/19

40. DT  (K), wind (knots), and 925–850 hPa  (10 -5 s -1 ) 18Z/19 Low-level Vorticity center

41. DT  (K), wind (knots), and 925–850 hPa  (10 -5 s -1 ) 00Z/20 PV tail thinning and breaking Source: NCDC GIBBS GOES-12

42. DT  (K), wind (knots), and 925–850 hPa  (10 -5 s -1 ) 06Z/20

43. DT  (K), wind (knots), and 925–850 hPa  (10 -5 s -1 ) 12Z/20

44. DT  (K), wind (knots), and 925–850 hPa  (10 -5 s -1 ) 18Z/20

45. DT  (K), wind (knots), and 925–850 hPa  (10 -5 s -1 ) 00Z/21 Source: NCDC GIBBS GOES-12

46. DT  (K), wind (knots), and 925–850 hPa  (10 -5 s -1 ) 06Z/21 Jerry?

47. 1345Z/21 VIS

48. 1445Z/21 VIS

49. 1545Z/21 VIS

50. 1645Z/21 VIS

51. Source: http://www.coolwx.com/buoydata Source: http://www.rap.ucar.edu/weather/surface 17Z/21

52. ~40 knots at landfall TPC Forecast from 12Z/21 Source: http://cimss.ssec.wisc.edu/tropic2/

53. Source: http://euler.atmos.colostate.edu/%7Evigh/guidance/index.htm

54. Extra slides

55. July 2006 CA over US

56. 500 hPa mean  (dam; solid contours), anomaly  (dam; shaded), and wind (knots; standard barbs) 15–22 July 2006

57. 1.0  NCEP–GFS Analyses 00Z/16 DT  (K) and wind (knots) 380 J kg -1 1680 J kg -1 Univ. of Wyoming X X

58. 1.0  NCEP–GFS Analyses 12Z/16 DT  (K) and wind (knots) 1500 J kg -1 Univ. of Wyoming X X X X

59. 10000 16000 15000 14000 13000 12000 11000 Date/Time (UTC) Height MSL (m) NOAA Profiler Obs 12Z/14 DT  (K) and wind (knots) X

60. Lapse Rate Climatology 1973–2007 Summer (JJA) 1200 UTC soundings Conditions: > 8.5 K km -1 > 2500 m deep 850–400 hPa layer 100 200 100 300 500 700 200 100

61. February 2004 over Australia

62. 200 hPa Height and Anomaly (dam), and Wind (m/s) for 1–22 Feb 2004 2.5  NCEP–NCAR Reanalysis

63. 12Z/14 DT  (K) and wind (knots) IR X PV tail mesoscale disturbance 1.0  NCEP–GFS Analyses T1 T2

64. 12Z/17 DT  (K) and wind (knots) IR X PV tail mesoscale disturbance X X 1.0  NCEP–GFS Analyses X X T1 T2

65. Mean Resultant Gradient-level Wind for January Figure from Atkinson (1971) Monsoon trough Trade winds Monsoon flow Is there a significant contribution from DT disturbances on the equatorward side of continental anticyclones to climatological monsoon precipitation over northern Australia? Australia