2nd year with La Niña Conditions [since 1950]: 1955, 1971, 1974, 1975, 1984, 1999, 2000, 2011
Following Year ASO ONI: -0.5, 1.6, -1.4, 0.6, -0.4, -0.5, -0.2, 0.3 [mean: -0.1]
n = 8 (# of years)
ASO = August, September, October; Aug–Oct period
ONI = Oceanic Niño Index
Cool ENSO (La Niña): 3
Cool neutral ENSO: 2
Warm neutral ENSO: 1
Warm ENSO (El Niño): 2
Neutral or cool ENSO: 6 (75%)
Warm ENSO: 2 (25%)
Based solely on these statistics, neutral or cool ENSO would seem to be heavily favoured for the peak (ASO) of the upcoming 2018 Atlantic hurricane season. Of course, there are many other factors to be considered besides climatology. Of the two El Niño events in the sample (1972, 1976), the former materialised as a strong event by ASO, the latter as a weak one. So only one out of the eight years sampled featured a +ENSO event of moderate or stronger status by ASO.
Tracks of All Storms (Tropical-Storm-Status or Stronger) for the Years Listed Above
(Years: 1956, 1972, 1975, 1976, 1985, 2000, 2001, 2012)
Left to right: ASO SST anomalies in 2000, 2001, and 2012; difference between ASO 500-mb heights in select years; difference between SST anomalies.
Since the +AMO has recently strengthened, I would give more weight to the +AMO samples (2000, 2001, and 2012, especially 2012, the most + of the years listed). For ASO of 2018, a stronger +AMO, (cool) neutral ENSO, slightly -NAO, warm Eastern-Seaboard SSTs, and more -PDO relative to recent years would 1) extend the Newfoundland ridging farther SW, 2) produce a weaker trough (and TUTT axis) over the far N Atlantic, and 3) shift the subtropical ridge farther NE. This would lower MSLP in the deep tropics and delay recurvature of storms that pass near the U.S., hence a westward shift in boxed tracks (mainly the leftmost box) relative to those shown in the first chart. This would mean an increased threat to the FL peninsula, GA, the Carolinas, and Cuba, while retaining the threat to the (rest of the) western Caribbean, eastern Gulf of Mexico, and mainland MX. Interestingly, the data suggest that TX might well see a break in this pattern.
This is VERY early and in no way is an official forecast!