Figure1: Oceanic Niño Index: 3 month running mean of ERSST.v4 SST anomalies in the Niño 3.4 region (5°N-5°S, 120°-170°W) Calculated from the ERSST V5 (at NOAA/CPC). Credit: ERSL/NOAA
The graph above compares this past La Nina that has just ended to other recent La Nina events. 2017-18 is pictured in black. It was a weak La Nina but clusters well with other events ending in the spring. Below is a look at these similar years tropical storms histories (depressions - tropical storms - hurricanes - major hurricanes).
The average storm numbers for the Atlantic are 10.1 named storms, 5.9 hurricanes and 2.5 major hurricanes. So these years listed shows well above average tropical cyclones, slightly elevated number of hurricanes and average number of Major hurricanes.
Also throwing out there a year seen mentioned a lot in the broken records and similarities, especially for the Northeast. It was a neutral year coming off an El Nino.
Looking at Tornado numbers through March.. There is some research showing low spring tornadoes can end in more hurricanes hitting land. This spring there has certainly been less tornadoes than usual with only 62 preliminary reports through March. Other years with similar numbers include:
Though the numbers here were average to above average, the big take away seems to be the track maps showing the much higher likely hood of landfalls on the Gulf of Mexico/Florida regions with the East Coast also showing a somewhat raised risk.
Before coming up with seasonal forecast numbers we'll need an in depth look at the global tropics scene. That will be another blog..
NOAA National Centers for Environmental Information, State of the Climate: Tornadoes for March 2018, published online April 2018, retrieved on May 12, 2018 from https://www.ncdc.noaa.gov/sotc/tornadoes/201803.