The Impacts of the Strong Subtropical Ridge of 2010Kevin S. Lipton, Meteorologist, NWS Albany NYRichard H. Grumm, SOO, NWS State College PAJason Krekeler, Meteorologist Intern, NWS State

College PA

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 2010persistent subtropical ridge over U.S.dictated heat-heavy rain-dry conditions

Methods DataJapanese 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.

NOAA – Warmest July on record (Land)

Worldwide land surface temperature was 1.03° C (1.85° F) above the 20 th century average of 14.3° C(57.8° F)

Summer of 2010 - Temps

Temperature Anomalies Standardized Temp Anomalies

Summer of 2010 - Precip

Precip Anomalies Standardized Precip Anomalies

BIRMINGHAM AL JACKSON MS

MOBILE AL TUPELO MS

LITTLE ROCK AR RALEIGH NC

PINE BLUFF AR WILMINGTON NC

BRIDGEPORT CT GREENSBORO NC

WASHINGTON REAGAN DC SALISBURY NH

DOVER DE ATLANTIC CITY NJ

WILMINGTON DE ISLIP NY

MIAMI FL NYC CENTRAL PARK NY

TALLAHASSEE FL CINCINNATI OH

SAVANNAH GA MT. POCONO PA

ATHENS GA PHILADELPHIA PA

INDIANAPOLIS IN PROVIDENCE RI

LOUISVILLE KY COLUMBIA SC

PADUCAH KY CHARLESTON SC

LAKE CHARLES LA CHATTANOOGA TN

BATON ROUGE LA GATLINBURG TN

BALTIMORE MD ROANOKE VA

SALISBURY MD RICHMOND VA

PORTLAND ME NORFOLK VA

Warmest Summer on Record at:

Summer 2010 (June-Aug)

Standardized Anomalies from the Japanese 25-year Reanalysis (JRA25) Data.

June 2010

July 2010

August 2010

July 2010 Mean August 2010 Mean

Differences from July to AugustMean 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.

July vs. August 2010 Precip Anomalies

Images created using NWS AHPS (Advanced Hydrologic Prediction Service) webpageat water.weather.gov/precip.

Heat Episode 3 – 7 July 2010

Using JRA25 Data

Heat Episode 3-7 July 2010 cont’d

Record Maxes 3–7 July 2010

Image courtesy of LongRangeWeather/Harris-Mann Climatologyat www.extremeweatherrecords.com

Heat Episode 17-25 July 2010

Using JRA25 Data

Record Maxes 17 – 25 July 2010

Image courtesy of LongRangeWeather/Harris-Mann Climatologyat www.extremeweatherrecords.com

Heat Episode 29 Aug – 2 Sep 2010

Using JRA25 Data

Record Maxes 29 Aug – 2 Sep 10

Image courtesy of LongRangeWeather/Harris-Mann Climatologyat www.extremeweatherrecords.com

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.

Summary

Persistent Subtropical Ridge over U.S. - Summer 2010heat eastern U.S.dry southern and eastern U.S.wet west and north of ridgesystem retrograded in August

Patterns and anomalies consistent with previous research

Ridge was relatively well predicted

Acknowledgements…

Co-Authors: Richard Grumm, Scientific Operational Officer,

and Jason Krekeler, NWS Intern – NWS State

College, PA

Neil Stuart, Lead Forecaster, NWS Albany, NY

ReferencesLipton, 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.]