09 September 2013

Humberto forms, could become season's first hurricane

This week is the climatological peak of the Atlantic hurricane season, but this year, it arrives with little fanfare.  Though there has not been a single hurricane yet, that could change very soon.

On Sunday evening, Tropical Depression 9 formed just off the African coast from a potent easterly wave.   This morning, it was upgraded to Tropical Storm Humberto, the ninth named storm of the season.  It is presently centered just south of the Cape Verde islands and tracking west at 12mph.

Enhanced infrared satellite image of Humberto at 8:30am EDT this morning.  (CIRA/RAMMB)
It is forecast to become a hurricane by Wednesday.  If you recall, the latest date of first hurricane formation in the aircraft reconnaissance and satellite era (back to 1944) is September 11, and that record was set back in 2002.  Specifically, it was 1200 UTC on September 11, and when it comes to the record, hours might count.  The 5am EDT forecast from NHC today brings Humberto to hurricane intensity at 0600 UTC (2am EDT) on the 11th.  But based on current appearance and trends, I'd suspect that the timeframe will be nudged forward/sooner.

Since 1851, 34 storms formed or passed within 100 miles of where Humberto did (18 of which were in September).  As you can see below, the tracks of these storms have large variability, ranging from a quick recurvature to long-tracked major hurricanes that plow into the U.S.  The current official forecast track for Humberto would be the quickest and furthest east recurvature off all of these.

Past tracks of all known storms that formed or passed within 100mi of where Humberto formed.
Models are in fairly good agreement on the quick recurvature scenario too, so the odds of it becoming a threat to land are extremely small.

Select model forecasts as well as the NHC forecast for Humberto, from the 0600 UTC runs today. (NCAR)
The name Humberto has been in the rotation since 1995 (that is, it has been used in 1995, 2001, 2007, and 2013).  It replaced Hugo, which was retired in 1989 after its devastating landfall on South Carolina on September 22 of that year.  In all likelihood, it will stick around for another reincarnation in 2019!

Elsewhere, the remnants of Gabrielle are still hanging around between Bermuda and Hispaniola.  The environment is likely going to remain too hostile for any tropical redevelopment, but it could become a stronger subtropical or extratropical cyclone and potentially impact, Bermuda, Newfoundland, or Nova Scotia.

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