Horel and Wallace, Monthly Weather Review, 1981.

1. The Downstream Influence of Organized Tropical Convection, Tropical Cyclones, and the Extratropical Transition of Tropical Cyclones over the Western PacificPatrick HarrNaval Postgraduate School L H L H L Nitta, JMSJ, 1987 Horel and Wallace, Monthly Weather Review, 1981.

2. Theme:Impacts as a Function of Scale and Season Global scale, slowly varying (intraseasonal) Madden-Julian Oscillation (MJO) seasonal: higher amplitude during northern winter and transition seasons Regional scale (seasonal, intraseasonal) Monsoon systems, equatorial waves seasonal: transition seasons summer hemisphere Synoptic Scale Equatorial waves, tropical cyclones, extratropical transition events seasonal: summer, transition seasons

3. Issues of Scale and Season • Madden-Julian Oscillation (Madden and Julian 1994, MJO) • Seasonal variability such that the strongest signal occurs during the Northern Hemisphere Winter. • Impacts due Rossby-wave response to regions of anomalous increased and decreased convection(divergent flow). • Heavy Precipitation events over western North America (Reynolds 2005) • “Pineapple Express” • Northern Summer impacts on tropical cyclones (especially in the eastern North Pacific (Maloney and Hartmann 2001) • Northern Summer impact on the North American Monsoon (Higgins and Shi 2001, Mo 2000). http://www.cpc.ncep.noaa.gov

4. Impacts during the winter of 2005: Southern California Rain Event http://www.wrh.noaa.gov/cnrfc

5. Feb 10-20, 2005 OLR anomalies http://www.cdc.noaa.gov http://www.bom.gov.au/bmrc/clfor/cfstaff/matw/maproom/OLR_modes

6. FEB 10-20, 2005 200 hPa Velocity Potential Anomalies 200 hPa Zonal Wind Anomalies 200 hPa height Anomalies Combination of events that lead to a circulation pattern that resulted in a deep trough over the eastern North Pacific http://www.cdc.noaa.gov

7. Feb 10-20, 2005 OLR anomalies http://weather.unisys.com/hurricane http://www.cdc.noaa.gov Enhanced convection over the central Pacific, which was associated with the eastward extension of the MJO and Rossby response toward North America, was also related to a major outbreak of tropical cyclone activity. Cyclone Meena 03-07 Feb 2005 Cyclone Olaf 13-20 Feb 2005 Cyclone Nancy 13-16 Feb 2005

8. PREDICTABILITY IMPACTS • Where can THORPEX help? • Role(s) of existing and proposed observations for definition of initial conditions. • -data assimilation issues • -special observations (i.e., satellite observations) • phasing with midlatitudes • Sensitivities to initial conditions and their propagation throughout the forecast cycle • Capitalize on the low-frequency variability of the MJO GFS 500 hPa Height Standard Deviation (measure of forecast difficulty, confidence, projected skill?) +120 h Increase in a “plume” of high standard deviation over the eastern North Pacific that is associated with the large-scale wave train. Reduced standard deviations exist over the Eastern Hemisphere +120 h

9. Although the MJO has far-reaching impacts, it exhibits a large amount of temporal and spatial variability. Other, smaller-scale factors such as equatorial Rossby waves can also cause far-reaching impacts during seasons when the MJO may be non-existent. 2001 2002 http://www.bom.gov.au/bmrc/clfor/cfstaff/matw/maproom/OLR_modes

10. Regional influences during the northern Summer season • Western North Pacific Monsoon/ Mei-yu: • Teleconnection with precipitation over the northern plains of North America (i.e., Wang et al. 2001, Lau and Weng 2000, Nitta 1987) (Wang et al. 2001)

11. 1200 UTC 07 Oct 2002

12. OLR Anomalies 200 hPa Height Anomalies http://www.cdc.noaa.gov Minnesota state area averaged precipitation anomalies June Oct 2002 http://www.cdc.noaa.gov/cgi-bin/Timeseries/timeseries1.pl

13. Minnesota Flood: 9-11 June 2002 From Dave Parsons

14. Wisc./Chi. flood event associated with the previous wave packet Mei-Yu convection Wisc/Chi. flood Mn flood

15. Pacific-Japan Teleconnection Patterns (Nitta 1987, Murakami and Matsumoto 1994, Wakabayashi and Kawamura 2004) • Associated with the western North Pacific summer monsoon • Also associated with anomalous sea-surface temperatures over the • Philippine Sea. • Impact summer pattern over Japan Regression maps of the 500 hPa streamfunction with the Pacific-Japan pattern for (a) June-August period, (b) June, (c), July, and (d) August a) JJA b) June d) Aug c) July Wakabayashi and Kawamura (2004)

16. IMPACTS OF EXTRATROPICAL TRANSITION EVENTS: TY Tokage, October 2004, Damage in Japan and to U.S. Navy ships in Japan.

17. http://oregonstate.edu/~readw/October1962.html

18. 0000 UTC 10 Oct 62 TY Emma TY Freda http://agora.ex.nii.ac.jp/digital-typhoon/ Large-scale wave train associated with the digging trough behind the extratropical transition of Emma and building ridge ahead of the extratropical transition of Emma contributed to the trough over the eastern North Pacific and the movement of the ex-Freda cyclone into the Pacific Northwest. http://www.cdc.noaa.gov Emma Ex-Freda 250 hPa height anomaly 9-13 Oct 1962

19. Maemi Isabel Isabel Maemi Fabian Newsweek, 03 July 2000 Source: NCEP/EMC model verification web page Impacts on Forecasting The movement of a tropical cyclone into the midlatitudes often induces a large downstream Rossby-wave like response. These large-amplitude circulation features are often mis-positioned, which contributes to errors in the forecast timing and interaction between the decaying tropical cyclone and the midlatitude circulation into which it is moving.

20. Impacts on Predictability A “plume” of increased std. dev. propagates downstream of the extratropical transition forecast position. Local maxima occur in the base of each successive trough of the ET-induced wave train. Largest variability exists over North America. • Where can THORPEX help? • Period of enhanced observations and impact assessment that concentrates on the warm-season, warm pool region to include the western North Pacific monsoon, TCs, and ET. • -phasing with the midlatitudes • -data assimilation impacts • Application to teleconnection-based high-impact weather events via OSSEs, etc. • Sensitivities to initial conditions and their propagation throughout the forecast cycle • Capitalize on the components of low-frequency variability TY Tokage ET Time TY Tokage http://agora.ex.nii.ac.jp/digital-typhoon/

21. Predictability Issues • There is little skill in predicting the onset of a MJO event • If it is recognized that an MJO event is present, then the predictability issue revolves around the response to the anomalous tropical conditions • Strength of response • Persistence of response • Phasing of response with midlatitude waves • Downstream extent of the response • Many monsoon variations occur at time scales that are longer than the synoptic time scale. Can this low-frequency variability be utilized to increase predictability associated with warm season precipitation? • There is a need to reduce the variability associated with the downstream response to the extratropical transition of tropical cyclones.