09 October 2016

Matthew transitions to a powerful extratropical cyclone off NC coast

A storm that we've been watching since it left the African coast as an easterly wave back on September 22nd has finally transitioned to an extratropical cyclone off the North Carolina coast.  The extratropical cyclone is centered just east of Cape Hatteras and still contains 75mph winds (Category 1 hurricane if it were still tropical) and is still producing significant storm surges in the area.

Hurricane Matthew, the first Category 5 hurricane in the Atlantic in nine years, left a trail of destruction in its path, from Haiti, Cuba, and Jamaica, up into the Bahamas, and finally the southeast United States. It remained a major hurricane (Category 3+ on the Saffir-Simpson scale) for a full week, which is very rare.

After two days of hugging the southeast coastline, Matthew did officially make landfall in the U.S., just north of Charleston, SC late Saturday morning as a Category 1 hurricane.

The record 11-year major hurricane "drought" in the U.S. continues, perhaps into at least next year, but let's not count this season out just yet.

In northern Florida, Georgia, South Carolina, and North Carolina, the wind speed was not the primary problem, or even secondary.  As usual, the flooding produced by the tropical cyclone was/is the big problem, caused by storm surge and by rainfall.  Kudos to the NWS and NHC for accurate storm surge and rainfall forecasts leading up to the event.

Keep in mind that the Saffir-Simpson scale (Category 1-5) only applies to the peak wind speed found in the storm, typically right near the center in the eyewall.  It does not contain any information on how large the wind field is, how much rain will fall, how deep the storm surge will be, etc.  The message to remember is "there's more to the story than the category".

3-day rainfall totals, from Thursday morning through Sunday morning (10/6-10/9). 
I have a long list of radar loops that cover much of Matthew's journey and lifecycle, from its genesis in the Windward Islands to its extratropical transition over eastern North Carolina: Tropical Cyclone Radar Loops

A series of excellent brief updates spanning the past couple of days can be found on the Capital Weather Gang blog.  Ex-Matthew is forecast to track eastward out to sea -- the loop scenario that appeared in forecasts for a few days did not come to fruition; the approaching trough was too strong.

If you recall a post I wrote back on September 28th, just as Matthew earned its name, I compared the long-range forecast track to that of 1954's Hurricane Hazel (which also occurred in October).  The outcome is remarkable... the genesis location, the abrupt right turn in the central Caribbean, the landfall on the western tip of Haiti, and a landfall in northern South Carolina.  Matthew just crept in closer to the Florida coastline and was stronger at its SC landfall.

[Matthew’s track is eerily similar to Hurricane Hazel’s in 1954]

Remarkable similarities between two October major hurricanes: Matthew 2016 and Hazel 1954.

Elsewhere, Tropical Storm Nicole is still drifting around further east in the Atlantic, and is forecast to accelerate and head for Bermuda on Thursday.

The next name on this year's list is Otto, but there is no new activity on the foreseeable horizon.

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