Tropical Depression Six was upgraded to Tropical Storm Fiona on Wednesday afternoon.  It became the earliest sixth- named storm since 2012, and formed about three weeks ahead of normal climatology.

The storm has sustained winds of 45 mph, but it looks ragged and disorganized.


Enhanced satellite image of Fiona where the low-level clouds are shaded in yellows while high clouds appear white. (NOAA)

Since the beginning of the reliable weather satellite era in 1966, only six other years have had six named storms so early in the season, including the hyperactive seasons of 1995 and 2005.  Of course, there is legitimate debate as to whether Alex back in January should be bundled up with  he 2016 calendar year, which is what officially counts, or the end of the 2015 season.

The environment around Fiona still favors additional strengthening for another day or so, but then conditions turn more hostile. The official intensity forecast from the National Hurricane Center reflects this, and it keeps Fiona as a minimal tropical storm Sunday through Tuesday as it continues its trek to the northwest, following a weakness in the subtropical ridge.

Consistent with what I noted yesterday, model track forecasts vary, but in a logical way.  The models (see below) that keep the storm weaker also allow it to stay further south and west, while models that have it as a stronger storm are much quicker to turn it to the north.  The National Hurricane Center’s track (labeled “OFCI”) essentially splits the difference.


Not all tracks shown here should be treated as equals. Some are very basic models, some are very sophisticated, and some just show a consensus of combinations of models already on here.


Forecast tracks for Fiona from Thursday morning’s guidance suite. (tropicaltidbits.com)

History strongly favors storms like this to turn to the north well before reaching the United States. The map below shows the tracks of all 22 tropical storms that passed within 100 miles of Fiona’s current position during August since 1851. The only storm that didn’t quite make the turn in time to remain safely out at sea was a Category 2 hurricane that hit North Carolina’s Outer Banks in 1933.


Tracks of the 22 tropical storms that passed within 100 miles of Fiona’s position on Thursday morning during August since 1851. (NOAA)