Friday Weather Discussion Clark Evans 27 March 2015

MJO Phase Diagram Peak amplitude on record (1974-present):

MJO & Tropical Wave Evolution

OLR: MJO and Anomaly

850/200 hPa u: MJO and Anomaly 850 hPa at left, 200 hPa at right.

850 hPa u: Full, Anomaly Full field at left, anomaly (from climo) field at right.

Equatorial Pacific Ocean State

ENSO Forecasts “…the dynamical models are anticipating a moderately strong event to develop in the Northern Hemisphere’s late spring and summer. They are notoriously bad for seeing through the spring predictability barrier, though, so it should be noted that the statistical models are more conservative, predicting a neutral-to- weak El Niño event.” IRI March 2015 Climate Briefing,

April-May-June 2015 Forecasts

Winter In Review

Dec 2014 – Feb 2015 Temperature

Dec 2013 – Feb 2014 Temperature

Dec 2014 – Feb 2015 Temperature

Dec 2014 – Feb 2015 Temperature

Dec 2014 – Feb 2015 Precipitation

Dec 2014 – Mar 2015 Precipitation

Dec 2014 – Mar 2015 Snowfall

Drought Monitor

500 hPa Height, Anomaly Derived from NCEP-NCAR Reanalysis, 1 December 2014 – 23 March

850 hPa Temperature, Anomaly Derived from NCEP-NCAR Reanalysis, 1 December 2014 – 23 March

Five Periods of Interest 5-27 December (warm) 29 December – 14 January (cold) January (warm) 1 February – 6 March (cold) 8-20 March (warm)

A Mild December

A Mild December Derived from NCEP-NCAR Reanalysis, 5-27 December

A Chilly New Year

A Chilly New Year Derived from NCEP-NCAR Reanalysis, 29 December 2014 – 14 January

Warmer and Dry in Late January

Warmer and Dry in Late January Derived from NCEP-NCAR Reanalysis, January

A Persistent Mid-Winter’s Chill

A Persistent Mid-Winter’s Chill Derived from NCEP-NCAR Reanalysis, 1 February to 6 March

Spring into March

Spring into March Derived from NCEP-NCAR Reanalysis, 8-20 March

Possible Pattern Influences

Possible Pattern Influences

Possible Pattern Influences SLP’ - SLP’ + SLP’ -

Possible Pattern Influences SLP’ - SLP’ + SLP’ -

Possible Pattern Influences +NAO very similar to +AO during boreal winter +PNA in winter: below- (above-) normal heights in C. Pacific (western N. America).

Possible Pattern Influences

Some Scientific Questions Why does the spring predictability barrier for ENSO exist, and will the current El Niño intensify or not? Why has anomalous cold occurred over North America and nowhere else in the last two winters? Why did the mid-latitude pattern evolve as it did on sub-seasonal scales? Can we even identify why? What caused the MJO to achieve such a high amplitude this March, and what does it mean?