September 20, 2006

1. Activities Related to Verification of Extremes in the United States via the National Climate Extremes Committee September 20, 2006 Jay H. Lawrimore Chief, Climate Monitoring Branch National Climatic Data Center (NCDC)

2. Overview • Background and Procedures of the NCEC • Existing Records • Four Record Investigations

3. Main Points To Be Made • An observation taken is not necessarily a record just because it was taken by an official observer • Review of national records is an excellent means for identifying broader observing / instrumentation problems • Assessments have been accomplished with and without travel to the observing site

4. National Climate Extremes Committee • Purpose • To assess the scientific merit of extreme meteorological/climatological events • To provide recommendation to NOAA management regarding the validity of related meteorological measurements • Also responsible for dissemination of public information and coordinating media inquiries • Established in 1997

5. National Climate Extremes Committee • Chaired by a representative from the NCDC • Typically the Chief of the Climate Monitoring Branch • Composed of additional representatives from the • National Weather Service • American Association of State Climatologists • Other members added on a case by case basis to provide expert analysis and consultation

6. National Climate Extremes Committee • Mandate restricted to national extreme values of several elements • Mandate does not include the reevaluation of existing extreme values for those listed • The list of elements may be expanded as additional element extremes are developed • Anecdotal and non-objective elements not included • E.g., short-duration rain rates

7. Event Team Members • Based on judgement of NCDC and the National Weather Service • Team assembled based on: • NCEC members • Personnel from site in question or the NWS COOP Program Manager • Others such as • State Climatologists, Regional Climate Center rep. • Others with specific technical and scientific expertise related to the event • Instrument Specialists, Snow Experts, etc.

8. Investigation Procedures • The measurement will be examined for compliance with established NWS guidelines and specifications • Team will assess • Observational procedures • Instrument exposure and operation • Reporting equipment maintenance and calibration • Documentation procedures

9. Poor Siting: Lamar, CO Photographs from Davey and Pielke, Sr. (2005)

10. Poor siting: Las Animas, CO Photographs from Davey and Pielke, Sr. (2005)

11. Proper Siting: Antequera, Spain Photograph courtesy of Tom Peterson

12. Conclusion of Investigation • Once investigating team has finalized its report the NCEC will • Provide a recommendation on the event to the Director of the NCDC, who will in turn determine the declaration • Document the findings • Provide a coordinated response to NOAA’s Public Affairs Office for the handling of media inquiries on the status of the investigation and validity of the report.

13. Things the NCEC Does Not Consider • Remotely sensed observations • Records that are not National in scope • Except those that relate to observational procedures/equipment issues that have the potential to impact national networks on a broad scale • Past records • Such as the 134F (56.7C) observation at Death Valley, California in 1913

14. Existing Records • Temperature • Maximum: 134F / 56.7C July 10, 1913 Greenland Ranch, California • Minimum: -80F / -62.2C January 23, 1971 Prospect Creek, Alaska • Max 24hr Change: 103F / 57.2C January 14-15, 1972 Loma, Montana

15. Existing Records • Snowfall • Maximum 24hr Snowfall: 75.8 in (192 cm) April 14-15, 1921 Silver Lake, Colorado • Maximum Seasonal Snowfall (July-June): 1140 in (2896 cm) 1998-1999 Mt. Baker Ski Area, Washington • Max Snow Depth: 451 in (1145 cm) March 11, 1911 Tamarack, California

16. Existing Records • Rainfall • Maximum 24 hour: 43 inches (109 cm) July 25-26, 1979 Alvin, Texas • Least Annual: 0.00 inches/0.00 cm 1929 Death Valley, California • Maximum Annual: 704.83 in (1790 cm) 1982 Kukui, Hawaii • Longest Dry Period: 767 days Oct 3, 1912-Nov 8,1914 Bagdad, California

17. Existing Records • Wind • Maximum Gust: 231 mph (103 m/s) April 12, 1934 Mt. Washington, NH • Hail (diameter/circumference) • Largest: 7“ / 18 3/4“ (17.8 cm / 47.6 cm) June 22, 2003 Aurora, NE • Heaviest: 1.67lb (0.76 kg) September 3, 1970 Coffeyville, KS

18. Existing Records • Pressure (mb/inches of Hg) • Lowest: 892.3/26.35 September 2, 1935 Matecumbe Key, FL • Highest: 1078.6/31.85 January 31, 1989 Northway, AK

19. Record Investigations • 24-hour Snowfall Record • Mantague, New York (Jan 11-12, 1997) • Seasonal Snowfall Record • Mt. Baker, Washington (July 1998 – June 1999) • Maximum 24-hour Temperature Change • Loma, Montana (Jan 14-15, 1972) • Largest Hail Stone • Aurora, Nebraska (June 22, 2003)

20. 24-hour Snowfall Record • Mantague, New York (Jan 11-12, 1997) • Reported to be 77 inch/195.6 cm (accumulation in 24 hrs) • Positive Results • New snowfall observing equipment and renewed adherence to NWS procedures and improved training • Negative Results • Observer quit

21. 24-hour Snowfall Record • Questions that arose when this event was reported by the media • Did a NWS field office have the authority to declare a new national record • Were proper procedures followed • Who would evaluate the event • There was no NCEC at the time • Ad hoc committee formed – 6 individuals • Travelled to site to view observing site, conduct interviews, and review procedures • Found that observer measurements followed local forecast office guidelines but NOT climatological guidelines

22. What was wrong? • Observer took 6 snowfall measurements in a 24-hour period on Jan 11-12 • 5 of them were within a 12-hour period to support NWS operations • The 6 measurements were summed to get a 24-hour total • Snow was very light and fluffy • NWS standards for climatological observations • No more than 4 Obs in 24 hours no more frequently than once every 6 hours • More frequent measurements taken by clearing the snow board tend to increase totals

23. 24-hour Snowfall Record • Conclusion of Committee • Improper observing techniques • New record discounted

24. Other Concerns Identified • Several cases of NWS stations taking hourly snow measurements and improperly adding these measurements to obtain 6-hour and 24-hour amounts • The availability and use of snow boards was sporadic or non-existent at numerous NWS locations • Some offices, where snow boards have not been utilized, have also been erroneously under measuring new snowfall by simply subtracting the old depth of snow on the ground from the new total snow depth to determine snowfall

25. Other Concerns Identified • Some climatological volunteer observers were not provided with the recently revised “NWS Snow Measurement Guidelines” • The lack of consistent adherence to standards can result in degraded data quality, inconsistent assessments, and the inability to accurately determine true variability and trends and rankings

26. Seasonal Snowfall Record • Mount Baker, Washington (July 1998-June 1999) • Reported to be new seasonal snowfall record of 1141 inches (2898 cm) • La Nina winter lived up to its reputation for storminess in the Pacific Northwest Snowbank at Mt. Baker Photo by David Zamechek

27. Seasonal Snowfall Record • Reasons for acceptance • Acceptable snowfall measurement methods • Once per day on a flat surface (seasonal total could have been higher) • Multiple sample depths averaged when drifting • Detailed record-keeping • Observers were knowledgeable and had 10-33 yrs exp. • Other corroborative evidence • Independent snow data from other sources • Eyewitness accounts • Unusual damage to trees and structures resulting from the crushing weight of the deep snow pack and avalanches.

28. Record 24-hour Temp Change • Loma, Montana (Jan 14-15, 1972) • -54F to 49F (103F) [-47C to 9C] • Eclipsed record set Jan 23-24, 1916 in Browning, Montana • Only record to be reviewed decades after the fact • Misunderstanding at the time that event could occur over 2 calendar days • No mechanism at the time to review such events • Local NWS Forecast Office requested review

29. Record 24-hour Temp Change • Arctic high (1048 mb), radiational cooling • Morning temperature on Jan 14 was -54F (47C) • High moved off to east • Chinook (downsloping westerly winds) • Bringing Pacific Maritime air down the mountains and into the Valley • Shortly after midnight, Jan 15, winds picked up to 30-40 mph • +34F (1C) near midnight • +45F (7C) by 6AM and 49F (9C) at 8AM

30. Largest Hailstone • Aurora, Nebraska • Diameter 7 in./17.8 cm • Circum: 18 ¾ in./47.6 cm • Problem: Hailstone was not preserved • Committee voted to accept measurements taken by NWS personnel from local field office

31. Main Points Made? • An observation taken is not necessarily a record just because it was taken by an official observer • Review of national records is an excellent means for identifying broader observing / instrumentation problems • Assessments have been accomplished with and without travel to the observing site

32. National Climate Extremes Committee on the Web http://www.ncdc.noaa.gov/oa/climate/monitoring/extremes/ncec.html