Same as 2013, 2014 was a year of rare intense weather events in the French West
Indies. The cyclonic activity over all North Atlantic basins, Caribbean Sea and Gulf of Mexico
has also proved to be below average.
Actually, only two tropical cyclones impacted West Indies: the first one was the
tropical storm Bertha, which went through Lesser Antilles on the 1st of August. The second
one was Gonzalo, a tropical cyclone that formed east of the Lesser Antilles and quickly
strengthened into a category one hurricane just before moving through the northern Leeward
Islands.
Fig1.
Gonzalo:
By 1200 UTC 12 October, the tropical depression which was moving westward
between 15 and 16 North and was located at about 400 km east of Guadeloupe became a
tropical storm. Gonzalo began to rapidly strengthen late on 12 October. An eye became
apparent in the imagery of the radar of Guadeloupe during the early hours of 13 October.
Gonzalo became a hurricane around 1200 UTC 13 October when it was located just east
southeast of Antigua, at about 40km north of Guadeloupe.
Fig2
Fig3
Radar of Guadeloupe: radial speeds, level 500m. Left: 13 oct 12utc; right: 13 oct 14utc
A 1-minute sustained wind of 67 kt with a gust to 78 kt was observed at 1244 UTC on
Antigua at V.C. Bird International Airport. Radar data of Guadeloupe are quite consistent with
the observations
RA IV/HC-37/Doc. 4.2 (7), p. 2
The hurricane continued to strengthen while it passed through the northern Leeward
Islands that afternoon. The southwestern portion of the eye moved over St. Barthélemy
around 2100 UTC, with the center of the eye crossing just north of the island about an hour
later. Gonzalo made landfall on the island of St. Martin at about 23 UTC .
Fig5
Fig4
Radar of Guadeloupe; october 13 at 20utc (16 h loc)
Satellite imagery visible channel October 13 at 21utc (17h loc)
Fig6
Max wind 1mn , 2mn et 10 minutes sustained winds at St Barthelemy airport .UTC time
RA IV/HC-37/Doc. 4.2 (7), p. 3
This phenomenon caused no casualties on the French islands, but it has caused local
damages. Many boats (about one hundred) were destroyed in the port of Gustavia. The latter
has been particularly exposed when the winds veered to the southwest sector after the eye
moved just north of the island.
Gonzalo management required a shift in red vigilance cyclone in the morning of 13,
followed by purple (involving containment measures) 3 hours later.
Crisis management. Warnings issued by Meteo-France
St. Martin- S.t Barthelemy
BS nr 01-10 .
BS nr 02-10 .
BS nr 03-10 .
12-10-2014 à 21h21 utc
13-10-2014 à 03h37 utc
13-10-2014 à 10h17 utc
Orange
Orange
Orange
BS
BS
BS
BS
BS
BS
BS
BS
13-10-2014 à 15h04 utc
13-10-2014 à 18h56 utc
13-10-2014 à 21h51 utc
14-10-2014 à 00h36 utc
14-10-2014 à 03h38 utc
14-10-2014 à 07h24 utc
14-10-2014 à 10h04 utc
14-10-2014 à 16h24 utc
Red
Purple
Purple
Purple
Purple
Purple
Grey
Vert
nr 04-10 .
nr 05-10 .
nr 06-10 .
nr 07-10
nr 08-10
nr 09-10
nr 10-10
nr 09-10
Heavy rains-Strong winds
Heavy rains-Strong winds
Heavy
rains-Strong
Dangerous sea
Cyclone
Cyclone
Cyclone
Cyclone
Cyclone
Cyclone
Cyclone
winds-
RA IV/HC-37/Doc. 4.2 (7), p. 4
Red level (all activities must stop) was issued one hour in advance before gusts reached
100km/h and four hours in advance before gusts reached 160km/h. Purple (level max :
containment) was issued only one hour ahead.
Forecasts:
Fig7
Hurricane
Tropical storm
It should be noted that according to the advisory of October 13-12utc, Gonzalo should
have moved south of ST Barth at a tropical storm level. Intensity and track forecasts were
much better at 18utc but it was a bit late.
Meteo-France had to anticipate a little on this upgrade to hurricane force. And thus
there were no complaints from the authorities, it certainly should have been better to issue
the purple level of warning at least one hour ahead the time it was actually done.
Anyhow, though the strengthening of Gonzalo was quite underestimated, MeteoFrance has been able, on Friday 10 April 2015, and thanks especially to the ensemble
prediction of ECMWF, to warn the civil authorities that bad weather was expected on
Leeward Islands on Sunday evening or Monday. Even if the matter was more about heavy
rain than about strong wind.
BERTHA
This cyclone developed on 1st August at about 450 km in the south-east of Barbados.
Then it crossed the Lesser Antilles as a tropical storm. The center passed just north of
Martinique late on 1 August. Surface observations in Guadeloupe reported maximum mean
winds (10mn) of 35 knots in la Désirade and Petite Terre (2 small islands east of Guadeloupe)
with gusts to 50 knots. In Martinique, the maximum mean wind was recorded on the Atlantic
RA IV/HC-37/Doc. 4.2 (7), p. 5
coast (Trinité-Caravelle) and reached 33knots. The maximum gust reached 47 knots.
Associated rains were locally stormy but did not give any significant amounts (30 to 60 mm in
the northern Martinique).
The most significant impacts reported by the media were on Martinique, where power
outages affected 150,000 buildings. In fact, the electrical network was already weakened
because of a serious technical event that happened in the previous weeks. So, the
consequences of the thunderstorms were not exactly related to the actual intensity of the
phenomenon.
Gusts. In km/h
10mn sustained winds
Surface wind speeds recorded in four locations of Martinique
Bertha, 1- 08_2015 12utc
Bertha, 1- 08_2015 18utc
Visible channel.
Hourly intensity
Berth
Martiniq
Martinique Radar Reflectivity at 20h45 utc.