15 August 2018

'Season of Slop' continues as Subtropical Storm Ernesto forms


Early Wednesday morning, a formerly-non-tropical low pressure over the north central Atlantic acquired subtropical characteristics and was upgraded to Subtropical Depression Five, then to Subtropical Storm Ernesto six hours later. In location, structure, and appearance, this is almost a duplicate of Debby last week.

In the satellite image above, note the smoke to the north and west of the storm and getting wrapped into the circulation... with the aid of backward trajectory analyses, I confirmed that the smoke originated all the way from the fires in the western U.S. about five days ago!!!


My phrase "season of slop" refers to the abnormal abundance of subtropical activity -- Alberto was subtropical for its entire life, Beryl was subtropical for the second half of its life, Debby was subtropical for its first day, and now Ernesto is subtropical.  So far only Chris was purely tropical, yet ironically spent its entire life in the subtropics!

Ernesto is in a favorable environment for some additional strengthening in the short term, but by the end of the week it will be over much colder water and transitioning to an extratropical cyclone as it zips off toward the northeast.

    Ernesto is a name from the original six lists, and its first appearance was in 1982. This is the name's 7th incarnation, and only the two most recent (2006 and 2012) became hurricanes.  The 2006 version hit the southern Florida peninsula as a tropical storm and the 2012 version hit the Yucatan peninsula as a Category 2 hurricane.



    07 August 2018

    Subtropical Storm Debby forms in far north-central Atlantic


    The fourth named storm of the 2018 Atlantic hurricane season, Debby, has formed about 1000 miles west of the Azores.  It has been a persistent mid-to-upper-level feature for about a week now, just drifting around, but it finally established a surface circulation and strong enough winds to earn an upgrade to a subtropical storm.  Note that as of now, it lacks the structure to be a fully tropical system. However, its time will be very limited -- it will pass over increasingly cold water and get absorbed into an approaching trough within a couple days.


    Debby is the third storm this season to be subtropical... Alberto began its life as a subtropical cyclone on May 25th, and the second half of Beryl's life was subtropical.  Climatologically, the 4th named storm forms on August 22, so Debby is about two weeks ahead of par.  In terms of ACE (Accumulated Cyclone Energy), the season is at 145% of average for this date.


    Aside from Debby, the Atlantic is quiet.  This time of year, we start looking to Africa for incipient waves/disturbances, but the water temperature in the deep tropical Atlantic between Africa and the Lesser Antilles remains cooler than average, which will be a suppressing factor for tropical cyclone activity there for a while.

    https://twitter.com/philklotzbach/status/1025424965108035584