September 20, 2006

September 20, 2006

Jay H. Lawrimore

Chief, Climate Monitoring BranchNational Climatic Data Center (NCDC)

Activities Related to Verification of Extremes in the United States via the

National Climate Extremes Committee

CCl Expert Team on Climate Monitoring

September 20, 20062

Overview

• Background and Procedures of the NCEC

• Existing Records

• Four Record Investigations


September 20, 20063

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


September 20, 20064


• 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


September 20, 20065


• 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


September 20, 20066


• 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


September 20, 20067

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.


September 20, 20068

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


September 20, 20069

Poor Siting: Lamar, CO

Photographs from Daveyand Pielke, Sr. (2005)


September 20, 200610

Poor siting: Las Animas, CO

Photographs from Daveyand Pielke, Sr. (2005)



Proper Siting: Antequera, Spain

Photograph courtesy of Tom Peterson



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.



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



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



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



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



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



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



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)



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




• 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



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




• Conclusion of Committee– Improper observing techniques– New record discounted



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



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



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



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.



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



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



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



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



National Climate Extremes Committee on the Web

http://www.ncdc.noaa.gov/oa/climate/monitoring/extremes/ncec.html

Documents

September 20, 2006