1. The Madden-Julian Oscillation and extreme precipitation in the contiguous United States Charles Jones Leila Carvalho 1, Jon Gottschalk 2, Wayne Higgins 2 1 University of California, Santa Barbara 2 Climate Prediction Center (CPC/NCEP)

2. 2 Outline  Motivation:  Extreme precipitation (CONUS, winter)  Madden-Julian Oscillation (MJO)  Forecast skill of extreme Precipitation  Relative value of deterministic forecasts  Spatiotemporal variations in extreme Precipitation in the CONUS and the MJO

3. 3 Extreme precipitation USA

4. Extreme precipitation Winter storm Heavy snow Snowpack Spring/summer water

5. o Most important mode of tropical intraseasonal variations o Time scales of 30 to 60 days o Anomalies propagate eastward along the tropical belt; phase speeds ~ 5 m s -1 o strong interaction with clouds, rain, surface winds and large-scale circulation The Madden-Julian Oscillation 5

6. 6 Anomalous upper level circulation (200-hPa) Enhanced Convection in the western Pacific Coupled Forced Rossby-Kelvin wave response Rossby waves - + - + Midlatitude wave train Kelvin wave - + Madden-Julian Oscillation (MJO) Life Cycle

7. 7 7 Barlow et al. (2005) Jones et al. (2004) Mo and Higgins (1998) Higgins et al (2000) Jones (2000) Bond and Vecchi (2003) Jones et al. (2004) Carvalho et al. (2004) Liebmann et al. (2004) Jones et al. (2004) Wheeler and Hendon (2004) Jones et al. (2004) Jones et al. (2004) Jones, C., D. E. Waliser, K. M. Lau, and W. Stern, 2004: Global occurrences of extreme precipitation events and the Madden-Julian Oscillation: observations and predictability. J. Climate, 17, 4575-4589. NH winter The MJO and Extreme Precipitation: Observations

8. 8 Madden-Julian Oscillation (MJO): influence on forecast skill and subseasonal predictability MJO o Waliser, D. E., K. M. Lau, W. Stern, and C. Jones, 2003: Potential predictability of the Madden-Julian Oscillation. Bull. American Meteo. Soc., 33-50. o Jones, C., D. E. Waliser, K. M. Lau, and W. Stern, 2004: Global occurrences of extreme precipitation events and the Madden-Julian Oscillation: observations and predictability. J. Climate, 17, 4575-4589. o Jones, C., D. E. Waliser, K. M. Lau, and W. Stern, 2004: The Madden-Julian Oscillation and its Impact on Northern Hemisphere Weather Predictability. Mon. Wea. Rev., 132, 1462-1471.

9. 9 Data and Methodology Definition of extreme precipitation  Observations: daily gridded precipitation over the contiguous United States, 1 Nov-31 Mar, 1981-2008.  Model:  NCEP CFS model: CMIP run (30 yrs)  NCEP CFS reforecasts (version 1)  Two levels of extreme precipitation: daily total exceeds the 75 th and 90 th percentiles of monthly pdf. Madden-Julian Oscillation (MJO): influence on forecast skill of extreme precipitation Jones, C., J. Gottschalck, L. M. V. Carvalho, and W. Higgins, 2010: Influence of the Madden-Julian Oscillation on forecasts of extreme precipitation in the contiguous United States. Monthly Weather Review (In press).

10. 10 NCEP CFS Model Reforecasts (v1) CFS Reforecasts IC 9-mo forecasts IC o 15 initial conditions per month o Forecasts out to 270 days (CFS seasonal forecast calibration) o Analyzed: forecasts out to 4 weeks For each forecast: o Remove mean model bias in precipitation field o Forecasts of extremes when precipitation exceeds adjusted 75 th or 90 th percentiles o Adjustment: ratios between observations and CFS CMIP run percentiles Analyzed deterministic and probabilistic forecast skill

11. 11  NCEP/NCAR reanalysis: U200, U850 intraseasonal anomalies  combined EOF  Phase diagram from PC1/PC2  MJO event has amplitude > 0.9  Phase rotates anti-clockwise  70 MJO events during 1 Nov-31 Mar, 1981-2008 (phases ~Wheeler and Hendon 2004) Enhanced convection

12. 12 Non-Probabilistic Forecasts: yes/no YESNO YESab NOcd Observations Forecast 2x2 Contingency Table n= a+b+c+d forecasts a c b d

13. 13 o Two samples: active MJO versus inactive (null) o Verification on MJO phases (≠ than MJO state in ICs) o Statistical significance: comparison of scores in active MJO with scores from resampled inactive cases Deterministic forecasts

14. 14 lead times (days) Forecast skill during active MJO 90 th percentile precipitation extreme Mean Heidke skill scores (HSS) over gridpoints that are significant at 5% level relative to inactive MJO conditions Min Max lead times (days) Min Max

15. YESNO YESab NOcd Event occurs Action taken Decision maker L= loss if event occurs and no action taken C= cost if action taken L 0 C C Jones, C., L. M. V. Carvalho, J. Gottschalck and W. Higgins, 2010: The Madden-Julian Oscillation and the relative value of deterministic forecasts of extreme precipitation in the contiguous United States. J. Climate (in press)

16. 16 Cost/loss ratio decision model Where V is value and: o  = user’s cost/loss ratio (C/L) o s = climatological base rate of the event (90 th extreme) o H = hit rate o F = false alarm rate When  = s potential forecast value Caveats: simple model, user’s actions expressed numerically, assume users are risk neutral-only concerned with long-term average expense Evaluated here with deterministic forecasts

17. 17 MJO

18. 18 Spatiotemporal variations in extreme precipitation in the contiguous United States and the Madden-Julian Oscillation Charles Jones and Leila M. V. Carvalho Spatiotemporal variations in extreme precipitation in the contiguous United States and the Madden-Julian Oscillation Charles Jones and Leila M. V. Carvalho Objective: develop a probabilistic approach to spatiotemporal variations in extreme precipitation in the CONUS during and relationships with the MJO Data and Methodology  Data: NCEP CPC Unified gridded precipitation, 0.5  lat/lon, 1 Nov – 31 Mar 1979-2010  Definition of extreme precipitation: daily average exceeds 90 th percentile of monthly pdf.

19. 19 Example of extreme precipitation

20. 20

21. 21 Contiguous Region of Extreme Precipitation (CREP) CREP: regions of spatially connected gridpoints in which daily precipitation exceed the 90 th percentile Properties: mean precipitation, area, orientation, elongation, frequency of occurrence during active MJO and inactive days Probabilities of CREPs occurrence given status of MJO, anomalies in geopotential height at 500-hPa

22. 22 Counts of CREPS during active MJO (top) and quiescent days (bottom). Counts were assigned to centers of each CREP during 1 November-31 March, 1979-2010. Total number of CREPs: 5600. Percentages of CREPS during active and inactive MJO days are indicated in parenthesis in each panel. Maximum number of counts are indicated on the left corner of each panel.

23. 23 Spatial and size distributions of CREPs during active MJO days. Circles indicate locations of centers of CREPs in each MJO phase; phases are shown on the bottom right corner of each panel. Sizes of circles represent areas (km 2 ); scale shown at the bottom. Total number of CREPs: 3869. Percentages of CREPs in each MJO phase are shown on the bottom left of each panel.

24. 24 January 1995 case study Dates MJO phases Centers of negative H500 anomalies CREPs Distances from center of H500 in which there is a probability Pb of occurring one or more CREPs

25. cost/loss ratio (C/L) Value of forecasts of extreme precipitation cost/loss ratio (C/L) Curves show value of forecasts averaged on 1-3, 5-7, 9-11 and 12-14 days lead times. Value MJO Phase 8 MJO Phase 1 Null

26. 26 Schematic representation of eastward propagation of tropical convective anomalies associated with the Madden-Julian Oscillation, changes in the Jet Stream and precipitation events in the Pacific Northwest. Tropical-Extratropical Interaction associated with Madden-Julian Oscillation