Arthur forms off Florida coast and pushes the season into action

For the sixth consecutive year, a named storm has formed prior to the official start of hurricane season on June 1. The topic of my previous post on Tuesday has been remarkably well-forecast by models and did indeed organize into a tropical storm north of the northern Bahamas on Saturday (see Odds increasing of a pre-season storm... AGAIN).

It was first upgraded to Tropical Depression 1 on Saturday afternoon, then to Tropical Storm Arthur on Saturday night.  Maximum sustained winds are at 40 mph and it is not expected to strengthen much more, but will, as mentioned on Tuesday, bring higher surf to the southeast US coast... and a shot at tropical storm force winds along the North Carolina coast as it heads out to sea.  As such, tropical storm warnings are in effect for the portion of the coast highlighted in blue below. Impacts should be fairly limited to extreme eastern North Carolina beginning Sunday afternoon and extending through Monday morning. The latest forecast can always be found at https://www.nhc.noaa.gov/

As mentioned at the beginning, there has been at least one pre-season named storm every year since 2015, which is bringing the trend over the past 50 years earlier and earlier. While the date of first hurricane formation is still easily contained by the artificial bounds of hurricane season, tropical and subtropical storms are forming earlier.

The date of first named storm formation over the past fifty years (1971-2020) shown by the blue line and dots. June 1 is marked by the aqua line, the median date is marked by the pink line, and the linear trend through the data is shown by the dashed gray line. 

The next names on this year's list are Bertha, Cristobal, and Dolly. Perhaps they will wait until after June 1st!

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