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Recurving Typhoons as Precursors to an Early Season Arctic Outbreak over the Continental U.S. Heather M. Archambault, Lance F. Bosart, and Daniel Keyser.

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Presentation on theme: "Recurving Typhoons as Precursors to an Early Season Arctic Outbreak over the Continental U.S. Heather M. Archambault, Lance F. Bosart, and Daniel Keyser."— Presentation transcript:

1 Recurving Typhoons as Precursors to an Early Season Arctic Outbreak over the Continental U.S. Heather M. Archambault, Lance F. Bosart, and Daniel Keyser Dept. of Earth and Atmospheric Sciences University at Albany, State University of New York Super Typhoon Oscar, 15 Sep 1995 (Source: NCDC website) NROW IX Wednesday, 7 November 2007 NSF Grant ATM

2 Motivation for Arctic Outbreak Case Study Document mechanisms linking continental U.S. Arctic outbreak to recurving western North Pacific typhoons (TYs) more than 100° longitude upstream Relate surface anticyclone associated with Arctic outbreak to surface anticyclone climatological study (Doody 2007)

3 Overview Impacts of the 20–22 September 1995 Arctic outbreak: Caused the earliest freeze on record in Chicago, IL Broke more than 120 U.S. daily record lows Cut short the growing season across much of the U.S. Plains Surface Temp. < 0°C, Week of 17–23 Sep 1995

4 18–22 Sep 1995: Extreme Temperatures 5-d mean 925-hPa temp. (contoured every 2°C) 5-d mean 925-hPa temp. anomaly (contoured every 2°C) 5-d mean 925-hPa temp. anomalies exceed  8°C over central and northern Plains, and +14°C over northern Alaska and Arctic Ocean

5 Presentation Outline Data sources Key Arctic outbreak mechanisms 1.W. Pacific TY recurvature and ridge amplification 2.Pacific–North American downstream development 3.Western North American blocking 4.North American surface anticyclogenesis Summary and conclusions

6 Data Sources 2.5° ECMWF ERA-40 reanalysis (sea level pressure (SLP) fields only) 1.125° ECMWF ERA-40 reanalysis 2.5° NCEP–NCAR reanalysis 925-hPa temperature and temperature anomaly plots –Constructed at NOAA Earth System Research Laboratory/Physical Science Division website (http://www.cdc.noaa.gov/Composites/Day/)http://www.cdc.noaa.gov/Composites/Day/ Japan Meteorological Agency best track plots –Obtained from Digital Typhoon website (http://agora.ex.nii.ac.jp/digital-typhoon/)http://agora.ex.nii.ac.jp/digital-typhoon/

7 1: TY Recurvature and Ridge Amplification Three typhoons recurve in the West Pacific within a 7-d period (16–22 Sep 1995) (Klein et al. 2000): –Super Typhoon (STY) Oscar (16 Sep) –TY Polly (19 Sep) –STY Ryan (22 Sep) Outflow from two of the three recurving TYs (STY Oscar and TY Polly) results in upper-level ridge amplification and jet intensification over the western Pacific (15–20 Sep)

8 STY Oscar (12–19 Sep 1995) Key: Tropical Depression Weak Tropical Storm Strong Tropical Storm Typhoon Extratropical Cyclone Japan Meteorological Agency Best Track Plot Large circles delineate 0000 and 1200 UTC Small circles delineate 0300, 0600, 0900, 1500, and 2100 UTC

9 STY Oscar (12–19 Sep 1995) Key: Tropical Depression Weak Tropical Storm Strong Tropical Storm Typhoon Extratropical Cyclone At 30°N, 1200 UTC 16 Sep Japan Meteorological Agency Best Track Plot 300-hPa vel. potential (contoured every 2  10 6 m 2 s  1 ), irrotational wind (plotted starting at 10 kt) 925-hPa rel. vorticity (shaded starting at 5  10  5 s  1 ) Large circles delineate 0000 and 1200 UTC Small circles delineate 0300, 0600, 0900, 1500, and 2100 UTC

10 At 30°N, 1200 UTC 20 Sep TY Polly (14–23 Sep 1995) Key: Tropical Depression Weak Tropical Storm Strong Tropical Storm Typhoon Extratropical Cyclone Japan Meteorological Agency Best Track Plot 300-hPa vel. potential (contoured every 2  10 6 m 2 s  1 ), irrotational wind (plotted starting at 10 kt) 925-hPa rel. vorticity (shaded starting at 5  10  5 s  1 ) Large circles delineate 0000 and 1200 UTC Small circles delineate 0300, 0600, 0900, 1500, and 2100 UTC

11 At 30°N, 1200 UTC 23 Sep STY Ryan (15–25 Sep 1995) Key: Tropical Depression Weak Tropical Storm Strong Tropical Storm Typhoon Extratropical Cyclone Japan Meteorological Agency Best Track Plot 300-hPa vel. potential (contoured every 2  10 6 m 2 s  1 ), irrotational wind (plotted starting at 10 kt) 925-hPa rel. vorticity (shaded starting at 5  10  5 s  1 ) Large circles delineate 0000 and 1200 UTC Small circles delineate 0300, 0600, 0900, 1500, and 2100 UTC

12 3-d Mean Plot: 12–14 Sep 1995 Circulation Before TY Recurvature Events Oscar Polly 300-hPa streamfunction (thick lines every 10  10 6 m 2 s  1 ) and nondivergent wind speed (shaded every 5 m s  1 starting at 35 m s  1 ); SLP (thin lines every 4 hPa)

13 3-d Mean Plot: 15–17 Sep 1995 Circulation During STY Oscar Recurvature Ryan Oscar Polly 300-hPa streamfunction (thick lines every 10  10 6 m 2 s  1 ) and nondivergent wind speed (shaded every 5 m s  1 starting at 35 m s  1 ); SLP (thin lines every 4 hPa)

14 3-d Mean Plot: 18–20 Sep 1995 Circulation During TY Polly Recurvature Ryan Oscar Polly 300-hPa streamfunction (thick lines every 10  10 6 m 2 s  1 ) and nondivergent wind speed (shaded every 5 m s  1 starting at 35 m s  1 ); SLP (thin lines every 4 hPa)

15 2: Downstream Development Upper-level ridge amplification results in downstream development across Pacific Ocean and North America (16–22 Sep)

16 1200 UTC 16 Sep hPa streamfunction (contoured every 10  10 6 m 2 s  1 ), nondivergent wind (plotted in kt), and meridional nondivergent wind speed (shaded every 10 m s  1 according to color bar)

17 1200 UTC 18 Sep hPa streamfunction (contoured every 10  10 6 m 2 s  1 ), nondivergent wind (plotted in kt), and meridional nondivergent wind speed (shaded every 10 m s  1 according to color bar)

18 1200 UTC 20 Sep hPa streamfunction (contoured every 10  10 6 m 2 s  1 ), nondivergent wind (plotted in kt), and meridional nondivergent wind speed (shaded every 10 m s  1 according to color bar)

19 1200 UTC 22 Sep hPa streamfunction (contoured every 10  10 6 m 2 s  1 ), nondivergent wind (plotted in kt), and meridional nondivergent wind speed (shaded every 10 m s  1 according to color bar)

20 3: Western North American Blocking Western North American omega blocking occurs in response to downstream development Cyclogenesis events in the Gulf of Alaska initiate block onset, maintenance, and “folding over” (anticyclonic wave breaking) ( 16–22 Sep)

21 1200 UTC 16 Sep –500-hPa thickness (dashed every 6 dam), 300-hPa wind speed (shaded every 5 m s  1 starting at 45 m s  1, and sea level pressure (solid contours every 4 hPa)

22 1200 UTC 17 Sep –500-hPa thickness (dashed every 6 dam), 300-hPa wind speed (shaded every 5 m s  1 starting at 45 m s  1, and sea level pressure (solid contours every 4 hPa)

23 1200 UTC 18 Sep –500-hPa thickness (dashed every 6 dam), 300-hPa wind speed (shaded every 5 m s  1 starting at 45 m s  1, and sea level pressure (solid contours every 4 hPa)

24 1200 UTC 19 Sep –500-hPa thickness (dashed every 6 dam), 300-hPa wind speed (shaded every 5 m s  1 starting at 45 m s  1, and sea level pressure (solid contours every 4 hPa)

25 1200 UTC 20 Sep –500-hPa thickness (dashed every 6 dam), 300-hPa wind speed (shaded every 5 m s  1 starting at 45 m s  1, and sea level pressure (solid contours every 4 hPa)

26 1200 UTC 21 Sep –500-hPa thickness (dashed every 6 dam), 300-hPa wind speed (shaded every 5 m s  1 starting at 45 m s  1, and sea level pressure (solid contours every 4 hPa)

27 1200 UTC 22 Sep –500-hPa thickness (dashed every 6 dam), 300-hPa wind speed (shaded every 5 m s  1 starting at 45 m s  1, and sea level pressure (solid contours every 4 hPa)

28 Anticyclonic wave breaking results in surface anticyclogenesis over central Canada and initial equatorward movement along the Rockies (18– 23 Sep) Strength and movement of surface anticyclone is associated with advection of anticyclonic geostrophic relative vorticity by the thermal wind (Sutcliffe–Trenberth approximation of quasigeostrophic forcing for vertical motion; Trenberth 1978) 4: North American Surface Anticyclogenesis

29 0000 UTC 18 Sep 1995 H 1000–500-hPa thickness (dashed every 6 dam), 700-hPa geo. relative vorticity (shaded every 3  10  5 s  1 starting at +/  3  10  5 s  1 ), and SLP (solid contours every 4 hPa)

30 0600 UTC 18 Sep 1995 H 1000–500-hPa thickness (dashed every 6 dam), 700-hPa geo. relative vorticity (shaded every 3  10  5 s  1 starting at +/  3  10  5 s  1 ), and SLP (solid contours every 4 hPa)

31 1200 UTC 18 Sep 1995 H 1000–500-hPa thickness (dashed every 6 dam), 700-hPa geo. relative vorticity (shaded every 3  10  5 s  1 starting at +/  3  10  5 s  1 ), and SLP (solid contours every 4 hPa)

32 1800 UTC 18 Sep 1995 H 1000–500-hPa thickness (dashed every 6 dam), 700-hPa geo. relative vorticity (shaded every 3  10  5 s  1 starting at +/  3  10  5 s  1 ), and SLP (solid contours every 4 hPa)

33 0000 UTC 19 Sep 1995 H 1000–500-hPa thickness (dashed every 6 dam), 700-hPa geo. relative vorticity (shaded every 3  10  5 s  1 starting at +/  3  10  5 s  1 ), and SLP (solid contours every 4 hPa)

34 0600 UTC 19 Sep 1995 H H 1000–500-hPa thickness (dashed every 6 dam), 700-hPa geo. relative vorticity (shaded every 3  10  5 s  1 starting at +/  3  10  5 s  1 ), and SLP (solid contours every 4 hPa)

35 1200 UTC 19 Sep 1995 H H 1000–500-hPa thickness (dashed every 6 dam), 700-hPa geo. relative vorticity (shaded every 3  10  5 s  1 starting at +/  3  10  5 s  1 ), and SLP (solid contours every 4 hPa)

36 1800 UTC 19 Sep 1995 H 1000–500-hPa thickness (dashed every 6 dam), 700-hPa geo. relative vorticity (shaded every 3  10  5 s  1 starting at +/  3  10  5 s  1 ), and SLP (solid contours every 4 hPa)

37 0000 UTC 20 Sep 1995 H 1000–500-hPa thickness (dashed every 6 dam), 700-hPa geo. relative vorticity (shaded every 3  10  5 s  1 starting at +/  3  10  5 s  1 ), and SLP (solid contours every 4 hPa)

38 0600 UTC 20 Sep 1995 H 1000–500-hPa thickness (dashed every 6 dam), 700-hPa geo. relative vorticity (shaded every 3  10  5 s  1 starting at +/  3  10  5 s  1 ), and SLP (solid contours every 4 hPa)

39 1200 UTC 20 Sep 1995 H 1000–500-hPa thickness (dashed every 6 dam), 700-hPa geo. relative vorticity (shaded every 3  10  5 s  1 starting at +/  3  10  5 s  1 ), and SLP (solid contours every 4 hPa)

40 1800 UTC 20 Sep 1995 H 1000–500-hPa thickness (dashed every 6 dam), 700-hPa geo. relative vorticity (shaded every 3  10  5 s  1 starting at +/  3  10  5 s  1 ), and SLP (solid contours every 4 hPa)

41 0000 UTC 21 Sep 1995 H 1000–500-hPa thickness (dashed every 6 dam), 700-hPa geo. relative vorticity (shaded every 3  10  5 s  1 starting at +/  3  10  5 s  1 ), and SLP (solid contours every 4 hPa)

42 0600 UTC 21 Sep 1995 H 1000–500-hPa thickness (dashed every 6 dam), 700-hPa geo. relative vorticity (shaded every 3  10  5 s  1 starting at +/  3  10  5 s  1 ), and SLP (solid contours every 4 hPa)

43 1200 UTC 21 Sep 1995 H 1000–500-hPa thickness (dashed every 6 dam), 700-hPa geo. relative vorticity (shaded every 3  10  5 s  1 starting at +/  3  10  5 s  1 ), and SLP (solid contours every 4 hPa)

44 1800 UTC 21 Sep 1995 H 1000–500-hPa thickness (dashed every 6 dam), 700-hPa geo. relative vorticity (shaded every 3  10  5 s  1 starting at +/  3  10  5 s  1 ), and SLP (solid contours every 4 hPa)

45 0000 UTC 22 Sep 1995 H 1000–500-hPa thickness (dashed every 6 dam), 700-hPa geo. relative vorticity (shaded every 3  10  5 s  1 starting at +/  3  10  5 s  1 ), and SLP (solid contours every 4 hPa)

46 0600 UTC 22 Sep 1995 H 1000–500-hPa thickness (dashed every 6 dam), 700-hPa geo. relative vorticity (shaded every 3  10  5 s  1 starting at +/  3  10  5 s  1 ), and SLP (solid contours every 4 hPa)

47 1200 UTC 22 Sep 1995 H 1000–500-hPa thickness (dashed every 6 dam), 700-hPa geo. relative vorticity (shaded every 3  10  5 s  1 starting at +/  3  10  5 s  1 ), and SLP (solid contours every 4 hPa)

48 1800 UTC 22 Sep 1995 H H 1000–500-hPa thickness (dashed every 6 dam), 700-hPa geo. relative vorticity (shaded every 3  10  5 s  1 starting at +/  3  10  5 s  1 ), and SLP (solid contours every 4 hPa)

49 0000 UTC 23 Sep 1995 H H 1000–500-hPa thickness (dashed every 6 dam), 700-hPa geo. relative vorticity (shaded every 3  10  5 s  1 starting at +/  3  10  5 s  1 ), and SLP (solid contours every 4 hPa)

50 Arctic Outbreak: A Rare Anticyclone Event Anticyclone associated with Arctic outbreak accounts for all SLP values ≥ 1035 hPa east of Rockies in 45-yr Sep climatology (Doody 2007)  At least a 1-in-45-yr event Count of ERA ° Reanalysis SLP ≥ 1035 hPa (4x daily, Sep 1958–2002) Image adapted from Doody (2007)

51 TY Recurvature Ridge Amplification 16  20 Sep 1995 Mechanisms Leading to Arctic Outbreak

52 Downstream Development Persistent Cyclogenesis 17  22 Sep 1995 Mechanisms Leading to Arctic Outbreak

53 Anticyclonic Wave Breaking Anticyclogenesis 18  22 Sep 1995 Mechanisms Leading to Arctic Outbreak

54 TY Recurvature Ridge Amplification Downstream Development Persistent Cyclogenesis Anticyclonic Wave Breaking Anticyclogenesis 16  23 Sep 1995 Mechanisms Leading to Arctic Outbreak

55 Conclusions 20  22 September 1995 continental U.S. Arctic outbreak is directly linked to recurving western Pacific typhoons via downstream development Surface anticyclone associated with Arctic outbreak is strongest September event in 2.5° ERA-40 dataset (1958  2002) Arctic outbreak characteristics are generally similar to characteristics of other documented cases (e.g., upstream omega block, surface anticyclogenesis, precursor cold surge, mountain range channeling) Apparent first documented case of an Arctic outbreak directly linked to upstream recurving tropical cyclones


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