2021 ORNL Mixing Height Average Std Dev By Local Daylight Time By Local Daylight Time and Season January 580.1 318.1 Hour Annual Std Dev Winter Avg Spring Avg Summer Avg Fall Avg February 595.1 330.0 1 422.0 202.5 485.3 469.9 380.9 352.6 March 659.0 472.5 2 434.3 226.6 490.8 509.7 384.8 352.1 April 868.7 705.7 3 424.4 188.1 504.6 462.7 385.5 345.7 May 849.8 797.1 4 409.4 161.0 481.0 423.9 377.1 356.5 June 820.7 767.5 5 388.9 181.7 481.8 400.1 351.2 323.7 July 1105.9 1228.2 6 369.3 160.9 438.6 403.2 329.8 306.6 August 958.0 1229.5 7 378.9 175.4 420.8 409.9 352.6 332.5 September 699.1 656.0 8 392.2 205.8 475.8 404.3 341.6 349.0 October 599.2 488.9 9 436.5 238.6 478.8 455.1 418.3 394.2 November 523.6 370.8 10 665.8 564.4 518.4 743.8 821.2 575.5 December 573.2 344.8 11 1017.8 767.1 535.8 1121.1 1452.2 912.2 12 1226.0 865.0 653.2 1258.5 1843.8 1111.8 Annual 737.4 13 1333.0 914.9 728.8 1373.8 2064.6 1149.8 Max 7538.0 14 1437.1 894.0 796.9 1491.6 2213.5 1230.3 Min 110.0 15 1538.0 1001.3 882.6 1510.8 2453.3 1288.2 Std Dev 736.7 16 1579.6 1006.0 917.6 1604.0 2462.1 1317.5 17 1516.7 1033.3 830.9 1592.2 2392.5 1233.2 18 1095.0 1014.8 603.4 1363.8 1823.5 572.9 19 500.0 426.8 563.6 673.5 416.5 346.0 20 439.8 310.9 516.2 524.1 368.5 321.2 21 436.1 283.2 553.3 471.4 375.4 351.0 22 413.1 229.8 515.3 441.0 373.3 324.1 23 419.4 231.6 523.8 421.5 379.8 354.0 24 425.4 230.0 519.9 469.9 361.5 351.6 2021 Synoptic Pressure Gradient 500-mb Pressure Height ORNL-NAM Boundary Layer Wind (kts) ORNL-NAM Boundary Layer Wind (kts) mb/km Average Std Dev Average Std Dev 850-mb Average Std Dev 925-mb Average Std Dev January 0.012 0.007 January 559.2 9.7 January 22.0 11.6 January 15.7 8.2 February 0.015 0.008 February 561.9 9.0 February 22.5 13.0 February 14.6 9.2 March 0.012 0.007 March 571.0 7.0 March 21.3 12.3 March 16.0 8.1 April 0.010 0.007 April 567.6 8.1 April 17.2 9.9 April 13.5 7.6 May 0.009 0.006 May 578.3 8.8 May 14.8 10.6 May 12.5 7.9 June 0.006 0.004 June 585.5 3.9 June 12.7 6.9 June 9.9 5.9 July 0.005 0.003 July 589.0 3.0 July 12.0 7.4 July 10.6 6.7 August 0.004 0.004 August 589.3 3.9 August 10.0 7.1 August 9.0 5.6 September 0.006 0.005 September 585.2 4.9 September 11.7 6.9 September 9.8 5.5 October 0.008 0.006 October 578.5 9.5 October 16.4 8.7 October 11.9 7.7 November 0.010 0.007 November 570.4 7.9 November 19.0 8.7 November 13.8 8.4 December 0.012 0.008 December 572.7 6.3 December 24.6 14.0 December 19.7 10.8 Annual 0.009 0.007 Annual 575.8 12.1 Annual 17.0 11.1 Annual 13.1 8.3