American Patterns

August 25, 2015
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The Pacific/North American teleconnection pattern (PNA) the most acknowledged, influential environment patterns into the Northern Hemisphere mid-latitudes beyond the tropics. It comprises of anomalies in geopotential level fields (typically at 700 or 500mb) noticed across western and east usa. You should observe that the PNA was discovered becoming strongly impacted by the El Niño-Southern Oscillation (ENSO) phenomenon. The positive stage associated with the PNA pattern is commonly connected with Pacific warm episodes (El Niño), in addition to unfavorable stage is commonly involving Pacific cold symptoms (Los Angeles Niña).

Great PNA

The positive stage comes with above typical geopotential heights on the western U.S. and below normal geopotential levels over the eastern U.S. This correlates to ridging over the western U.S., and deep troughing throughout the east. The net outcome of the height industry design within period is the fact that it causes cool atmosphere moving into Canada to plunge southeastward, which results in below typical temperatures on the east U.S. and above normal conditions within the western U.S.

  • Research in the SCO shows that a confident PNA, specially during an El Niño year, produces an above average quantity of winter months occasions in NC
500mb Level Anomalies During a Positive PNA
Exterior Temperature Anomalies During an optimistic PNA

Into the positive period, above average geopotential levels are noticed within the western U.S., and unhealthy geopotential heights have emerged over the east U.S. This causes heated air moving much further north than usual throughout the western U.S., while cool, Canadian environment is forced southward over the eastern U.S. resulting in below typical temperatures.

Unfavorable PNA

The bad stage functions troughing and below normal geopotential heights across western U.S. and ridging with above typical geopotential levels on the eastern U.S. the end result is substandard conditions for western U.S., and above typical conditions within the east U.S.

  • Research during the SCO shows that a poor PNA usually results in a decreased prospect of cold weather
    weather condition in NC
500mb Height Anomalies During an adverse PNA
Exterior Temperature Anomalies During a Negative PNA

The negative period of this PNA design functions substandard geopotential heights over the western U.S., and above normal geopotential levels throughout the eastern U.S. This results in deep troughing over the western U.S., that allows cold atmosphere from western Canada to drain southward into this area. In eastern U.S., cozy, damp environment through the gulf in addition to Atlantic Ocean can travel northward, often resulting in above regular conditions and much more humid problems.