Top 10 Most Unusual Tropical Weather Events of 2015

What makes this year interesting has been the number of unusual storm tracks, out-of-season systems and intense tropical cyclones in parts of the world.

The first fact actually comes from the South Pacific. Yes, the Southern Hemisphere gets tropical cyclones too!

#10: Earliest and Latest Cyclone on Record in the South Pacific

Tropical Depression 17F formed on June 30, 2015, becoming the latest tropical cyclone on record in a South Pacific tropical cyclone season, which runs from July 1 to June 30. The system crossed into the Australian tropical region later in the day and strengthened to become Tropical Cyclone Raquel.

The system moved back into the South Pacific two days later on July 2, as a tropical depression, becoming the earliest tropical cyclone on record in the basin, now in the 2015-16 season. If that wasn't enough, a second tropical depression, 01F, formed just a few weeks later on Aug. 1.

To put this into some perspective, it could be compared to a tropical system forming in December in the Atlantic Ocean and also existing there in January, followed by another system on February 1.

#9: Bill Spends 83 Percent of Its Life Over Land

Tropical cyclones may thrive over water, but that does not mean that they cannot move inland. That said, it is unusual for such a storm to remain tropical for any extended period of time over land.

But after making landfall in Texas as a tropical storm, Bill moved north across the Plains and east into the Mississippi and Ohio valleys before finally becoming post-tropical in eastern Kentucky.

(MORE: Tropical Storm Bill Leaves Behind Flooding)

Bill spent three days over land, or 83 percent of its total life span as a tropical cyclone, while it was only over water as a named system for about 14 hours.

#8: Odd Storm Tracks in the Central and Eastern Pacific

Tropical Storm Olaf became the first tropical cyclone on record to start in the eastern Pacific, move westward into the central Pacific and turn back east into the eastern Pacific in October 2015. By doing so, the Central Pacific Hurricane Center (CPHC) handed off responsibility for tracking the system to the National Hurricane Center (NHC).

Olaf wasn't the first oddly-tracking system of the season in the central Pacific. Oho developed south of Hawaii and moved northeast earlier in October, most likely joining only 1982's Ema for such a track.

(MORE: Hurricane Oho Recap)

An unnamed hurricane in 1975 also moved northeast in the central Pacific, but to the north of Hawaii. Although the 1975 storm and Ema both crossed the 140 degrees West back into the eastern Pacific before dissipating, Olaf was "almost certainly" the first system handed off between the basins from CPHC to NHC, according to NHC hurricane specialist Eric Blake.

#7: Ana, Second Earliest U.S. Tropical Cyclone Landfall on Record

The Atlantic tropical cyclone season does not officially begin until June, but that didn't stop an Atlantic tropical storm from making landfall in May.

Tropical Storm Ana began as a subtropical storm on May 7, but transitioned to a purely tropical storm before making landfall near Myrtle Beach, South Carolina, on May 10.

(MORE: Tropical Storm Ana Recap)

The only other tropical storm to make landfall earlier in a calendar year in the U.S. was an unnamed tropical storm in February 1952, which struck southern Florida.

#6: 64 Atlantic Hurricanes in a Row Have Not Hit Florida

Florida is often at the center of attention when it comes to hurricanes in the Atlantic Basin, which includes the Gulf of Mexico. Despite that fact, another year is going by without an Atlantic hurricane hitting the state.

(MORE: 10 Years Later, Still No Hurricanes Have Hit Florida)

With hurricanes Danny, Fred and Joaquin all missing the U.S. in 2015, there have now been 64 hurricanes in a row across the Atlantic Basin that have not hit Florida, a record according to Dr. Phil Klotzbach, a Colorado State University research scientist specializing in tropical cyclones.

The last hurricane to strike the state was Wilma on Oct. 24, 2005, so the Florida hurricane drought has extended past the 10-year mark.

#5: A Category 5 Landfall With No Fatalities

Hurricane Patricia became the strongest hurricane on record on Oct. 23, 2015. At one point, sustained winds reached 200 mph and the storm's central pressure fell to 879 millibars. Among all tropical cyclones known to modern science, only a few typhoons in the Western Pacific have ever been stronger.

Even with weakening prior to reaching Mexico's Pacific coast, Patricia made landfall as a Category 5 hurricane near Cuixmala, Mexico. Maximum sustained winds were estimated at 165 mph.

A combination of a relatively small core wind field with Patricia, sparse population near the point of landfall and preparedness led to no reported fatalities. Patricia is likely the only Category 5 landfall on record to not cause any deaths.

(MORE: How Did Mexico Escape Patricia with No Deaths?)

#4: Central Pacific Record Number of Tropical Cyclones

The central Pacific has been unusually active this season, with several tropical systems threatening Hawaii.

Although no tropical cyclones have made a direct landfall in Hawaii, the central Pacific has seen a record-shattering 15 cyclones this season. Eight of those systems formed in the central Pacific, also a record, while seven originated in the eastern Pacific, later crossing into the central Pacific.

The previous record for the number of cyclones passing through the central Pacific basin in one year was 11 tropical cyclones in 1992 and 1994. The previous record number of cyclones originating in the central Pacific was just four in 1982 – which like 2015 was the beginning of a strong El Niño.

#3: Joaquin, Latest Bahamas Category 4 Hurricane on Record

Despite an early start to the 2015 Atlantic tropical season, things remained fairly tame through the climatological peak of the season in September. 

That suddenly changed when Joaquin rapidly intensified near the Bahamas to become a Category 4 hurricane on the first day of October. By doing so, it was the latest Category 4 (or stronger) hurricane on record to impact the Bahamas.

Not only was Joaquin an intense hurricane, but it also persistently lashed the Bahamas for two days.

(MORE: Hurricane Joaquin Recap)

#2: Three Central/Eastern Pacific Category 4 Hurricanes at the Same Time

In late August not one, not two, but three Category 4 hurricanes were active in the central or eastern Pacific Ocean at the same time: Kilo, Ignacio and Jimena. This was the first time on record that this has happened.

(MORE: Three Category 4 Hurricanes in the Pacific Ocean)

The instance of two simultaneous major hurricanes (Kilo and Ignacio) in the central Pacific by itself was also a first for the basin that has seen record tropical cyclone activity this year.

At the time, this was only the third occurrence on record of three major hurricanes or equivalent typhoons (Category 3 or stronger) in the entire north Pacific simultaneously. However, less than two months later, this happened again when Olaf and Patricia were ongoing as major hurricanes in the central and eastern Pacific, while Champi was a Category 3 equivalent typhoon in the western Pacific.

#1: Record Number of Category 4-5 Tropical Cyclones

Despite only one coming from the Atlantic, the Northern Hemisphere has seen a record-shattering 25 Category 4 and 5 tropical cyclones in 2015, based on analysis from the NHC, CPHC and the U.S. military's Joint Typhoon Warning Center.

This number of storms far exceeds the previous record of 18 in the seasons of 1997 and 2004, according to Dr. Klotzbach.

The Category 5 cyclones were Atsani, Dolphin, Maysak, Noul, Patricia and Soudelor. (Patricia was the only Category 5 outside of the western Pacific)

The Category 4 cyclones were: Andres, Blanca, Champi, Chan-Hom, Chapala, Dolores, Goni, Hilda, Ignacio, In-fa, Joaquin, Kilo, Koppu, Mujigae, Nangka, Olaf and Sandra.

The only North Atlantic storm that made this list was Hurricane Joaquin.

It should be noted that worldwide reliable accounting of tropical cyclones has only been possible since the 1970s, when weather satellites enabled tropical cyclones to be detected in remote stretches of ocean without needing ships or aircraft to observe them.