Teleconnections

This winter We wondered…….. Why has this winter sucked so much? The answer is TELECONNECTIONS!

What are teleconnections? They are climate anomalies that relate to interactions between weather patterns throughout the whole world Some rely on sea temperatures and some rely more on atmospheric conditions

Ever heard of….. El Nino? La Nina? North Atlantic Oscillation? Arctic Oscillation? PNA, PDO, MJO, AAO These are all teleconnections

ENSO El Nino (warm)/La Nina (cold) events Measures temperature anomalies in the Pacific Ocean between the coast of South America and Eastern Asia El Nino is warmer than average off of Peru. La Nina is cooler than average

La Nina Right now we are under a strong La Nina Typically, the NW US has above average rainfall while Western Canada and Alaska are colder than average The NE US is warmer than average and slightly wetter. Lows tend to move farther to our west

La Nina SST

North Atlantic Oscillation Takes the height measurements between Iceland and the Azores Measures the strength of the Icelandic low and the Azores or Bermuda high

Positive phase In positive phase, the Icelandic low is stronger than average and the Bermuda high is also stronger The pressure gradient increases which increases the westerlies This leads to warm, wet conditions in the NE US Lows tend to go to our west under the positive phase, which is what we’ve been under this winter

NEGATIVE PHASE POSITIVE PHASE http://www.ldeo.columbia.edu/res/pi/NAO/

NAO Index

Arctic Oscillation

AO Index

Pacific Decadal Oscillation 20-30 year cycle measures the difference between SST in the west and northeast Pacific

PDO Breakdown http://www.atmos.washington.edu/~mantua/REPORTS/PDO/PDO_egec.htm

ENSO-PDO Connection Temperatures and precip extremes are higher when both the ENSO and PDO are in phase (like this winter)

Everything together Positive NAO La Nina Positive AO Lows tend to go to our west, putting us in the warm sector of most lows La Nina Tend to have wetter winters, but warmer as well Positive AO Colder air stays to our North, weaker jet

AccuWeather