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)
Overview
• Background and Procedures of the NCEC
• Existing Records
• Four Record Investigations
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September 20, 2006
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
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September 20, 2006
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
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September 20, 2006
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
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September 20, 2006
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
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September 20, 2006
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.
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September 20, 2006
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
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September 20, 2006
Poor Siting: Lamar, CO
Photographs
Davey
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Team on Climatefrom
Monitoring
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September
20, 2006
and Pielke,
Sr. (2005)
Poor siting: Las Animas, CO
Photographs
Davey
CCl Expert
Team on Climatefrom
Monitoring
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September
20, 2006
and Pielke,
Sr. (2005)
Proper Siting: Antequera, Spain
11
Expert Team on Climate Monitoring
PhotographCCl
courtesy
of Tom Peterson
September 20, 2006
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.
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September 20, 2006
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
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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
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September 20, 2006
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
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September 20, 2006
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
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Existing Records
• Wind
– Maximum Gust: 231 mph (103 m/s)
12, 1934 Mt. Washington, NH
April
• 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
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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
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September 20, 2006
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)
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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
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September 20, 2006
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
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September 20, 2006
What was wrong?
• Observer took 6 snowfall measurements in a 24hour 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
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September 20, 2006
24-hour Snowfall Record
• Conclusion of Committee
– Improper observing techniques
– New record discounted
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September 20, 2006
Other Concerns Identified
• Several cases of NWS stations taking hourly
snow measurements and improperly adding
these measurements to obtain 6-hour and 24hour 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
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September 20, 2006
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
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September 20, 2006
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
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September 20, 2006
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.
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September 20, 2006
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
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September 20, 2006
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)
• Shortly after midnight, Jan
– Bringing Pacific Maritime
15, winds picked up to 3040 mph
air down the mountains
– +34F (1C) near midnight
and into the Valley
– +45F (7C) by 6AM and 49F
(9C) at 8AM
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September 20, 2006
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
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September 20, 2006
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
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September 20, 2006
National Climate Extremes
Committee on the Web
http://www.ncdc.noaa.gov/oa/climate/monitoring/extremes/ncec.html
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September 20, 2006