Michael Erickson led a discussion titled, “A Glimpse at What This Upcoming Winter Might Have to Offer?”
Mike started weather discussion with a brief review of the past weeks weather. Long Island found itself on the east side of a strong 500 hPa ridge over the weekend, which resulted in high temperatures reaching the low to mid 80’s on Saturday and Sunday. Thereafter a weak offshore low developed and persisted, resulting in cooler cloudier conditions with easterly flow. A weak upper level low propagated into the region, supporting the continued weak offshore surface cyclogenesis and easterly flow. The low finally propagated east today, with a return to something called sunshine.
Thereafter focus shifted to an attempt at a seasonal “forecast,” although “experiment” might be a better word choice than “forecast.” Mike would be lying if he considered himself a seasonal forecast in any sense. When making a seasonal forecast, Mike focused on lower frequency variability metrics which would likely change slowly such as El Nino Southern Oscillation (ENSO), the Quasi-Biennial Oscillation (QBO), the Atlantic Multi-decadal Oscillation (AMO) and the Pacific Decadial Oscillation (PDO). Similar previous years are identified using these low frequency metrics, and their winters are analyzed. Currently we are in ENSO neutral conditions leaning toward an El Nino with a 60-70% chance of an El Nino forming this fall or winter (according to the CPC). The QBO is negative and expected to peak in the negative phase this winter. The PDO is in a cold phase, although in the shorter term, most of the northern Pacific is experiencing above normal sea surface temperatures (SSTs). In fact, most of the Northern Hemispheres SSTs are above normal, which is an anomalous signal. Finally the AMO is in its warm phase.
All of these metrics are discussed in Mike’s 2014-2015 “Experiment.” A quick summary of the results show that years most similar to our current 2014 fall experienced below normal temperatures in the eastern 1/3 to 1/2 of the country. Of the most similar years, about 60% of them were below normal. A quick glimpse at precipitation shows above normal precipitation in most of the Southeast United States, normal precipitation for the Long Island region and below normal precipitation for Northern New England and New York. These results should be taken with a grain of salt, but there does appear to be a weak signal in the composites considered.