Mary D. Stampone Department of Geography New Hampshire State Climate Office University of New Hampshire Presentation to the New England - St. Lawrence Valley (NESTVAL) Geographical Society Annual Meeting. Reference: Stampone, M.D. (2010). New Hampshire Winter 2009/2010: Summary and Historical Context. New England - St. Lawrence Valley Geographical Society (NESTVAL), October 29 – 30, 2010, Storrs, CT.

1. New Hampshire
Winter of 2009/10:
Summary, Statistics and
Historical Perspective
NESTVAL
October 30, 2010
Mary D. Stampone
New Hampshire State Climatologist

2. El Niño Arrives – July 2009
July 1, 2009 sea surface temperature anomalies for the equatorial eastern Pacific.
(http://www.noaanews.noaa.gov/stories2009/20090709_elnino.html)
By early July 2009, sea surface temperatures along the
equatorial eastern Pacific reached 1°C above average
indicating the development of an El Niño.

3. El Niño Arrives – July 2009
Year
1975 1980 1985 1990 1995 2000 2005 2010
Warm (red) and cold (blue) episodes based on a threshold of +/- 0.5oC for the Oceanic Niño Index (ONI) [3 month running
mean of ERSST.v3b SST anomalies in the Niño 3.4 region (5oN-5oS, 120o-170oW)], based on the 1971-2000 base period.
(http://www.cpc.noaa.gov/products/analysis_monitoring/ensostuff/ensoyears.shtml)
ONI
A weak El Niño developed by early July 2009, strengthening to
a moderate to strong event by February 2010.

4. Typical El Niño influences on world weather patterns during December-January-February.
(http://www.ncdc.noaa.gov/paleo/ctl/images/warm.gif)
Influences on US Winter Weather
El Niño, or the warm phase of the El Niño-Southern Oscillation
(ENSO), can influence weather patterns across the continental US.

5. December-January-February (A) temperature anomalies and (B) frequency of
occurrence (%) for El Niñ0 events 1956 - 2005.
(http://www.cpc.noaa.gov/products/precip/CWlink/ENSO/composites/)
During an El Niño winter, the north Great Plains states tend to be
warmer and the southeastern US tends to be cooler than normal.
(A) (B)
Influences on US Winter Weather

6. December-January-February (A) precipitation anomalies and (B) frequency of
occurrence (%) for El Niñ0 events 1956 - 2005.
(http://www.cpc.noaa.gov/products/precip/CWlink/ENSO/composites/)
During an El Niño winter, the western US tends to be wetter and
the southeastern US tends to be cooler than normal.
(A) (B)
Influences on US Winter Weather

7. December-January-February (A) snowfall anomalies and (B) frequency of
occurrence (%) for El Niñ0 events 1956 - 2005.
(http://www.cpc.noaa.gov/products/precip/CWlink/ENSO/composites/)
During an El Niño winter, northern tier states tend to receive
below normal snowfall.
(A) (B)
Influences on US Winter Weather

8. December-January-February temperature distribution for (A) Northern (climate zone 01) and (B) southern (climate zone 02)
New Hampshire for El Niñ0 events 1956 – 2005.
(http://www.cpc.noaa.gov/products/precip/CWlink/ENSO/box_whiskers/plots/temp/temp.seas.djf.b50.e08.div.002.png)
However, El Niño is not a useful indicator for seasonal
forecasting in New England.
(A) (B)
Influences on US Winter Weather

9. December-January-February precipitation distribution for (A) Northern (climate zone 01) and (B) southern (climate zone 02)
New Hampshire for El Niñ0 events 1956 – 2005.
(http://www.cpc.noaa.gov/products/precip/CWlink/ENSO/box_whiskers/plots/temp/temp.seas.djf.b50.e08.div.002.png)
However, El Niño is not a useful indicator for seasonal
forecasting in New England.
(A) (B)
Influences on US Winter Weather

10. New England – Winter 2009/10
warmer than normal north.
New England (A) temperature (°F) and (B) precipitation departures for the winter of 2009/10.
(http://www.nrcc.cornell.edu/page_regional.html)
Overall, the New England winter of 2009/10 was …
wetter than normal south.

11. New Hampshire – Winter 2009/10
Average temperature, in degrees Fahrenheit, and total precipitation, in inches, for the winter
of 2009/10 and percent of normal (1971-2000).
(http://www.ncdc.noaa.gov/oa/climate/research/cag3/nh.html)
Winter began with near normal
temperatures during December of 2009
but temperatures warmed considerably
by the second week of January and
continued through February.
Temperature Precipitation
2010 % Normal 2010 % Normal
December 23.5 98 4.25 121
January 21.9 120 2.53 74
February 26.4 125 4.17 159
Winter 23.9 113 10.95 116
Winter began with above normal
precipitation (mostly snow) during
December of 2009 but January
remained dry with a mix of snow and
rain events throughout February.

12. Average daily meteorological winter (December-January-February) temperatures for New
Hampshire from 1971 through 2009.
(http://www.ncdc.noaa.gov/oa/climate/research/cag3/nh.html)
New Hampshire – Winter 2009/10
El Niño Years:
2009/10
2006/07
2004/05
2002/03
1997/98
1994/95
1991/92
1987/88
1986/87
1982/83
1977/76
1976/77
1972/73

13. Average daily meteorological winter (December-January-February) temperatures for New
Hampshire El Niño winters (1971-2010).
(http://www.ncdc.noaa.gov/oa/climate/research/cag3/nh.html)
New Hampshire – Winter 2009/10
El Niño Years:
2009/10
2006/07
2004/05
2002/03
1997/98
1994/95
1991/92
1987/88
1986/87
1982/83
1977/76
1976/77
1972/73
Temperature(°F)

14. Winter 2010/11 Outlook
Moderate to strong La Niña means equal chances for above
normal, normal, or below normal conditions for New England.

15. The New Hampshire State Climate Office (NHSCO) resides within the
Department of Geography at the University of New Hampshire.
The NHSCO is officially recognized by the American Association of
State Climatologists and the National Oceanic and Atmospheric
Administration (NOAA).
New Hampshire State Climate Office
Mary D. Stampone
State Climatologist