How in the hell do you explain this:
Winter in Big Cities of the East Ranked Among the Coldest Since 1950 -
HIGH LATITUDE BLOCKING AND RECORD SNOWCOVER A KEY TO THIS WINTER
Written March 10, 2003
by Joe D'Aleo
Chief WSI/INTELLICAST Meteorologist
In our winter outlook in the fall we showed why the oceans were in a mode, which favored enhanced high latitude blocking, which would make this El Nino colder than the ones we were used to in recent decades.
The degree of high latitude blocking is measured by two climate indices, the North Atlantic and Arctic Oscillations. In recent stories, we showed how the negative mode of both modes favored colder and often snowier than normal conditions in the eastern United States and Europe, even in El Nino winters. The indices were at or near the most negative values observed since 1950 especially during the early winter from October to December.
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| October to December Arctic Oscillation values were the most negative since 1950. This high latitude blocking helped generate large polar and arctic air masses that helped build deep snowcover and make the winter very cold for many areas in the hemisphere. |
This high latitude blocking helped generate extensive polar and arctic air masses that brought extreme cold to places in the Northern Hemisphere. Here in North America, the flow pattern entrained frigid Siberian air to join with the cold high pressure building in Canada. The coldest air was focused on the eastern states.
With the large cold air masses came much more snow than normal across the hemisphere. In fact, according to the data compiled at the CPC, the extent of the Northern Hemisphere's snowcover from October through February was the greatest since records were started in 1973. It even exceeded the deep snowcover of the winters of the late 1970s.
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| October to February 2002/03 average snowcover for the Northern Hemisphere was at the highest level in the data set eclipsing the previous record set in the winter of 1976/77. From CPC: ftp://ftp.ncep.noaa.gov/pub/cpc/wd52dg/snow/snw_cvr_area/NH_AREA |
PERSISTENT COLD WEATHER FROM OCTOBER TO FEBRUARY
El Nino winters are characterized dependably by a ridge in the western parts of North America and a trough in the eastern areas. With the productive Polar Regions and extensive snowcover, temperatures in the trough in the eastern states averaged persistently below normal. Temperatures during the October to February period ranked among the top ten winters since 1950 in many cities in the northeast.
In Boston, it was the second coldest such period just behind 1976/77.
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BOSTON, MASSACHUSETTS
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Year
|
Average Temperature
|
|
1976/77
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35.42
|
|
2002/03
|
35.72
|
In New York City, the period ranked 4th coldest since 1950 behind the two memorable cold winters in the late 1970s (1976/77 and 1977/78) and the winter of 1967/68.
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CENTRAL PARK, NEW YORK
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|
Year
|
Average Temperature
|
|
1976/77
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37.55
|
|
1967/68
|
38.25
|
|
1977/78
|
39.35
|
|
2002/03
|
39.70
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In Rochester, New York, the winter ranked 7th coldest since 1950, tied with the winter of 1969/70 (our top analog year).
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ROCHESTER, NEW YORK
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Year
|
Average Temperature
|
|
1976/77
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29.48
|
|
1993/94
|
30.38
|
|
1962/63
|
30.38
|
|
1981/82
|
31
|
|
1978/79
|
31.44
|
|
1969/70
|
31.56
|
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2002/03
|
31.56
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In Baltimore (BWI Airport), the winter ranked 3rd coldest behind 1976/77 and 1962/63.
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BALTIMORE, MARYLAND
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|
Year
|
Average Temperature
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|
1976/77
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37.04
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1962/63
|
37.16
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2002/03
|
38.63
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What a difference a year can make. Many of these same locations during the same period last year found temperatures ranking among the warmest on record as resurgent solar activity produced a shrunken polar vortex and enhanced zonal flow, which in turn maximized the maritime influence on the continents and limited the extent of the snowcover. It also led to near record drought that lingered through the summer in many areas.
These two years demonstrate how many factors combine to choreograph the weather and climate as we march from season to season and year-to-year on our ride through time.