Discussion: Summertime has arrived and a careful eye on ocean surface temperatures in the North Atlantic and East Pacific in regard to tropical cyclone potential, ENSO and the general weather pattern increases importance.
In the North Atlantic the persistent cool pool of water south of Greenland most summertime seasons since 2013 is biased west this summer to the New England and Southeast Canada Maritime Coast (Fig. 1) which should bias those areas cool for summer. South of the cool pool the North Atlantic SSTA is warm and trended much warmer last week from near Bermuda and eastward. Waters in the outer tropical North Atlantic where most hurricanes develop are now cooler than normal and trending cooler. The bottom line in the North Atlantic is favorability for tropical cyclones which could strengthen rapidly over the western basin where SSTA is warm and getting warmer.
In the East Pacific basin all eyes are on the ENSO regime (Fig. 2). Waters in the eastern equatorial Pacific have cooled again while most of the weak El Nino warmth has convened near and just east of the Dateline. An El Nino Modoki look is out there and dynamic models favor that scenario continuing. The cool waters north of Hawaii compared with warm surface of the northeast Pacific indicate a warm phase Pacific decadal oscillation is present. The +PDO regime supports an upper level dry/warm ridge pattern during summer although mostly in Western Canada versus the West Coast given the latest observations.
Fig. 1-2: The North Atlantic and East Pacific weekly SSTA analysis.