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Monthly Atlantic Tropical Weather Summary

ABNT30 KNHC 011150

Monthly Tropical Weather Summary
NWS National Hurricane Center Miami FL
800 AM EDT Sun Oct 1 2017

For the North Atlantic...Caribbean Sea and the Gulf of Mexico:

The North Atlantic basin was extremely active in September.  Four
tropical cyclones formed, all of which became hurricanes, and three
of those four became major hurricanes.  Hurricane Irma was also
present in the basin as a major hurricane during the month, although
it formed in late August.  Both Irma and Maria reached category 5
intensity during the month of September.

Based on a 30-year climatology (1981-2010), the number of named
storms forming in the basin during September was near average, but
the numbers of hurricanes and major hurricanes were both well above
average.  In terms of the Accumulated Cyclone Energy (ACE), which
measures the combined strength and duration of tropical storms and
hurricanes, September 2017 was the most active month on record,
easily breaking the previous record of September 2004.  Overall,
this September was about 3.5 times more active than an average
September from 1981-2010.

From a seasonal perspective, activity in the Atlantic basin so far
in 2017 is well above average, and this season is the 3rd most
active on record to date in the basin, behind 1933 and 2004.

Reports on individual cyclones, when completed, are available at
the National Hurricane Center website at .

Summary Table

Name                 Dates         Max Wind (mph)
TS Arlene            19-21 Apr            50*
TS Bret              19-20 Jun            45
TS Cindy             20-23 Jun            60
TD Four               6- 7 Jul            30
TS Don               17-18 Jul            50
TS Emily         31 Jul- 1 Aug            45
H  Franklin           6-10 Aug            85
H  Gert              13-17 Aug           105
MH Harvey        17 Aug- 1 Sep           130
MH Irma          30 Aug-12 Sep           185
MH Jose               5-22 Sep           155
H  Katia              5- 9 Sep           105
MH Lee               15-30 Sep           115
MH Maria             16-30 Sep           175

* Denotes a storm for which the post-storm analysis is complete.

Hurricane Specialist Unit

Preliminary Atlantic Tropical Cyclone Tracks
Preliminary Atlantic Tropical Cyclone Tracks