Observed inverted V soundings and downstream severe weather in New York and Pennsylvania

1. Observed inverted V soundings and downstream severe weather in New York and Pennsylvania Mike Evans NOAA/NWS Binghamton, NY Barry Lambert NOAA/NWS State College, Pa

2. Outline • Motivation • Methodology • Climatology of inverted V events • Major vs. minor events • Low CAPE major vs. High CAPE major events • Conclusion

3. Motivation – August 17, 2007

4. August 17, 2007 – upper air

5. August 17, 2007 - radar

6. Severe Reports • 24 wind damage reports • Damage was mostly trees down • Damage occurred from the Finger Lakes through northeast Pa • No extra staffing!

7. August 17, 2007 Albany – 00z, August 18 Buffalo – 00z, August 18

8. April 8, 2010

9. April 9, 2010 00z – upper air

10. April 8, 2010 - radar

11. April 8, 2010 - Severe reports • 13 wind damage reports • Damage was mostly trees down • Damage in southern New York through northeast Pa • No extra staffing!

12. April 8, 2010 - sounding

13. Methodology • Examine events from 2005-2010 • Major events – 20 or more reports in New York and Pennsylvania • Minor events – 1 to 4 reports in New York and Pennsylvania • Identify events that occurred with inverted V soundings based on a subjective examination of 12z soundings at PIT and BUF and examination of trajectory forecasts

14. Methodology / Climatology • 28 of 79 major events occurred with an upstream inverted V sounding (35 percent). • 38 of 140 minor events occurred with an upstream inverted V sounding (27 percent).

15. Inverted V criteria • Define a strict criteria for an inverted V sounding: - 925-800 hPa lapse rate at least 7.5 C/km - surface-800 hPa max Tdd greater than 7 C - 800-500 hPa min Tdd less than 4 C • Result – 9 major events, 14 minor events.

16. Major vs. Minor Events • 9 major events – 424 severe reports - 374 severe wind reports (88 percent) • 14 minor events – 30 severe reports - 22 severe wind reports (73 percent)

17. Major vs. Minor Events - charts

18. Major vs. Minor Events - Charts

19. Major vs. Minor Events - composites 500 mb heights – major events 500 mb heights – minor events Surface temperatures – major events Surface temperatures – minor events

20. Low CAPE vs. High CAPE major events - charts

21. Low CAPE vs. High CAPE major events - composites 500 mb heights – low CAPE majors 500 mb heights – high CAPE majors Surface temperatures – low CAPE majors Surface temperatures - high CAPE majors

22. Summary / Conclusion • Inverted V soundings found upstream from approximately 30 percent of major and minor severe weather events • Inverted V events are mostly severe wind producers • Results indicate that sounding and anomaly data can be used to identify major events • Forecasters should take special care to anticipate low CAPE major events