For the entire Northern Hemisphere, there is evidence of an increase
in both storm frequency and intensity during the cold
season since 1950,1 with storm tracks having shifted slightly towards the poles.2, 3 Extremely heavy snowstorms increased
in number during the last century
in northern and eastern parts of the United States, but have been less frequent since 2000.11,15 Total seasonal snowfall has generally decreased
in southern and some western areas, 16 increased
in the northern Great Plains and Great Lakes region, 16,17 and not changed
in other areas, such as the Sierra Nevada, although snow is melting earlier
in the year and more precipitation is falling as rain versus snow.18 Very snowy
winters have generally been decreasing
in frequency
in most regions over the last 10 to 20 years, although the Northeast has been seeing a normal number of such
winters.19 Heavier - than - normal snowfalls recently observed
in the Midwest and Northeast U.S.
in some years, with little snow
in other years, are consistent with indications of increased blocking (a large scale pressure pattern with little or no movement) of the wintertime circulation of the Northern Hemisphere.5 However, conclusions about trends
in blocking have been found to depend on the method of analysis, 6 so the assessment and attribution of trends
in blocking remains an
active research area.
He also said the ongoing strong El Niño event
in the Pacific Ocean may have influenced the storm track of this storm as well as the extra heat present
in the Atlantic, since the Atlantic tends to have less
active hurricane
seasons and
winter storm
seasons during El Niños, allowing warm water anomalies to persist.