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The Impacts of the Strong Subtropical Ridge of 2010

The Impacts of the Strong Subtropical Ridge of 2010. Kevin S. Lipton, Meteorologist, NWS Albany NY Richard H. Grumm , SOO, NWS State College PA Jason Krekeler , Meteorologist Intern, NWS State College PA. Introduction. Mid-latitude heat waves (Lipton et al. 2005)

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The Impacts of the Strong Subtropical Ridge of 2010

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  1. The Impacts of the Strong Subtropical Ridge of 2010 Kevin S. Lipton, Meteorologist, NWS Albany NY Richard H. Grumm, SOO, NWS State College PA Jason Krekeler, Meteorologist Intern, NWS State College PA

  2. Introduction • Mid-latitude heat waves (Lipton et al. 2005) • Above normal heights (500 hPa) • above normal 700 & 850 hPa temps  • moisture surge over west flank of ridge • Heat event of Summer 2010 • persistent subtropical ridge over U.S. • dictated heat-heavy rain-dry conditions

  3. Methods Data • Japanese 25-year Reanalysis (JRA25) used for most images. • 1.25° x 1.25° grids. • Climate Mean and Standard Deviations used to compute standardized anomalies were from NCEP/NCAR Re-analysis (1980-2010). • 2.5° x 2.5° • GrADS used in producing images. • NCEP GFS also used (35 km grid) but not shown. • Led to finer details for PW values/anomalies • High PW surge underestimated by reanalysis data as much as 5 to 15 mm when averaged over a month, with similar differences noted when comparing daily images.

  4. NOAA – Warmest July on record (Land) Worldwide land surface temperature was 1.03° C (1.85° F) above the 20th century average of 14.3° C (57.8° F)

  5. Summer of 2010 - Temps Temperature Anomalies Standardized Temp Anomalies

  6. Summer of 2010 - Precip Precip Anomalies Standardized Precip Anomalies

  7. Warmest Summer on Record at:

  8. Summer 2010 (June-Aug) Standardized Anomalies from the Japanese 25-year Reanalysis (JRA25) Data.

  9. June 2010

  10. July 2010

  11. August 2010

  12. July 2010 Mean August 2010 Mean

  13. Differences from July to August • Mean 500 hPa Ridge shifted westward by August. This allowed for frequency of heavy rain episodes and MCS’s across central U.S. to diminish in August. • 850 hPa Temperature Anomalies of +0.5 to +1.0 SD in July shifted further south and west during August, remaining mainly southwest of the megalopolis. • Enhanced upper level jet across northern Plains during July shifted slightly west into northern Rockies during August. Also – enhanced upper level jet developed across Bahamas and Florida during August.

  14. July vs. August 2010 Precip Anomalies Images created using NWS AHPS (Advanced Hydrologic Prediction Service) webpage at water.weather.gov/precip.

  15. Heat Episode 3 – 7 July 2010 Using JRA25 Data

  16. Heat Episode 3-7 July 2010 cont’d

  17. Record Maxes 3–7 July 2010 Image courtesy of LongRangeWeather/Harris-Mann Climatology at www.extremeweatherrecords.com

  18. Heat Episode 17-25 July 2010 Using JRA25 Data

  19. Record Maxes 17 – 25 July 2010 Image courtesy of LongRangeWeather/Harris-Mann Climatology at www.extremeweatherrecords.com

  20. Heat Episode 29 Aug – 2 Sep 2010 Using JRA25 Data

  21. Record Maxes 29 Aug – 2 Sep 10 Image courtesy of LongRangeWeather/Harris-Mann Climatology at www.extremeweatherrecords.com

  22. Characteristics/Differences – 3 Heat Episodes • All 3 Heat Episodes displayed similar characteristics with past eastern U.S. Heat Events: • 500 hPa Anomalies of at least +1 to +2 SD. • 850 hPa Temperatures of +1 to +2 SD. • 5940 m closed contour in mean with 17-25 JULY and 29 Aug – 02 Sep. • Juxtaposition of 850 and 700 hPa Anomalies (Not shown). • Some slight differences: • For 3 – 7 July 2010, no 5940 m closed contour in mean • Did show up in daily values initialized with GFS. • PWAT surge on N/W side of heat affected region/ridge less prominent, especially for 17-25 July and 29 Aug-02 Sep Events. • JRA25 and NCEP/NCAR Reanalysis may have been too course as much higher values shown in GFS.

  23. Summary • Persistent Subtropical Ridge over U.S. - Summer 2010 • heat eastern U.S. • dry southern and eastern U.S. • wet west and north of ridge • system retrograded in August • Patterns and anomalies consistent with previous research • Ridge was relatively well predicted

  24. Acknowledgements… • Co-Authors: • Richard Grumm, Scientific Operational Officer, and • Jason Krekeler, NWS Intern – NWS State College, PA • Neil Stuart, Lead Forecaster, NWS Albany, NY

  25. References • Lipton, K., R.H. Grumm, R. Holmes, P. Knight, and J. Ross, 2005: Forecasting heat waves using climatic anomalies. 21st Conf. on Weather Analysis and Forecasting/17th Conf. on Numerical Weather Prediction, Washington, D.C., Amer. Meteor. Soc., P1.60. [Available online at http://ams.confex.com/ams/pdfpapers/94498.pdf.]

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