“Early Warnings in Caribbean Hurricanes: A Cuban case-study”.
Dr. José Rubiera
Director
National Forecasting Center, Instituto de Meteorología.
Havana, Cuba.
Introduction:
The Cuban National Forecast Center at the Instituto de Meteorología started in
1996 a new approach on hurricane warnings. The primary idea consisted in
providing the public with early warnings 3-5 days in advance. Then, more
accurate forecasts and warnings are issued for the 24-48 hour period before a
hurricane strikes. A case-study is presented in this paper, based on the
experiences obtained with hurricane “Michelle”, a deadly Category 4 hurricane
that hit Central Cuba in early November 2001.
Early Warnings in Hurricanes.
Hurricane warnings were issued with just a few hours before the hurricane strike
in late XIX and early XX Centuries, with almost no time left for preparation. The
great changes undergone by science and technology, mainly in the last decades
of the last Century, lead to a continuos increase in accuracy and longer forecast
periods. Five day forecasts are nowadays as good as three day forecast were
10 to 20 years ago. Observational technology, i.e. aircraft reconnaissance, radar
and satellite techniques, give a better data coverage of oceanic areas. Weather
Numerical Models, with improved physics and better data input, have produced
a jump in modern forecasting techniques. Telecommunications and Internet
have provided fast and reliable access of updated information to forecasters
around the world.
The Cuban National Forecasting Center (NFC) started a new approach in the
issuance of hurricane warning information from 1996. Early Warning Bulletins
are issued 3 to 5 days in advance, at 24 hour intervals, followed by regular
warnings every 6 hours, with 24 to 48 hours in advance.
The main consideration of NFC is to warn the public with enough time in
advance, increasing the amount of information gradually, creating the sense of a
coming danger, without panic. The historic experience of NFC’s forecasters,
who have the heritage of more than a Century in hurricane forecasting, give
additional advantages to Cuban Meteorological Service, besides the use all the
modern techniques such as Numerical Models. The knowledge and expertise of
the forecasters remain the main decision factor.
A very careful aspect is that of the wording used in the Early Warning Bulletins.
The information on the tropical cyclone must be given with enough details and
the general philosophy of the forecast should be explained, but not in a technical
language that is not understood out of the meteorological service, but rather in
plain words. The forecast itself is a compromise between incertitude, normal in
any weather forecast, and the deterministic forecast that people would like to
have. Instead, people should be conveyed to realize that a completely accurate
forecast is impossible to have with so much time in advance, and that gradual
approximations to reality will follow, urging people in the threatened area to be in
contact with future warning releases to pinpoint the most probable hit area
The main actors: National Forecasting Center - Government and Civil
Defense - Media.
Cuban experience with Early Warning during the last 8 years show that the best
results are obtained with a combination of coordinated efforts of various main
actors. On the first hand the National Forecasting Center that issues the early
warning forecasts and coordinate it with Civil Defense and Government
authorities. The Government and Civil Defense put their plans into action, with
timely protective measures. The Media plays a very important role in conveying
forecast and warnings to the people, mainly through radio and TV. A kind of
conditioning reflex has been created in the public that usually watch the weather
report with the forecaster located in TV station newsroom and feels that
everything is normal. However, the forecaster makes the radio and TV
broadcast from the NFC office whenever there is a warning posted. When he
finishes, a Civil Defense officer has a broadcast from the Civil Defense
Headquarters, giving guidelines on how to act and what to do when the storm
arrives. In this case, people realizes that something is about to happen and pay
greater attention to the information.
The frequency of information also increases with time. The Civil Defense
declares an “Informative” stage 72 hours before the hurricane is forecasted to
affect a particular area. In this case, the Media increases the amount of
information on the hurricane. The “Alert” stage is posted 48 hours before and the
“Alarm” stage 24 hours before the hurricane strike. All preparedness and
evacuation should be concluded in this last stage.
Hurricane “Michelle”: A case Study.
Tropical Depression #15 formed October 29th, 2001, near Puerto Cabezas,
Nicaragua. On October 31st, when the center of circulation was over water,
Tropical Depression #15 was upgraded to Tropical Storm “Michelle”. It
intensified rapidly. On November 1st it already was a hurricane. Upper air and
surface conditions favored strengthening to major hurricane force in about 24 to
36 hours. Medium Range Forecasts and Climatology suggested that it would hit
Cuba as a Cat 3-4 hurricane within a 3-4 day time frame. On November 3rd
“Michelle” was a major hurricane Category 4 in the Saffir-Simpson Scale.
Shortcomings to be faced and Strenghs found to deal with this major
hurricane.
The overall analysis of the meteorological situation and the facts that 1) no
major hurricane has hit Cuba since 1952 and therefore two generations of
Cubans didn’t know the effects of a major hurricane Cat 3 or 4 as the one that
was expected. In fact, Cubans only had historical memory of Cat 1
(Georges/1998) and Cat 2 (Lili/1996) hurricanes, and 3) the hurricane was
expected to hit Cuba just during the week-end, where most people rest.
However, there were also strengths that the Countryr took advantage of: 1) the
majority of the population is educated, 2) people has confidence in the National
Forecasting Center and Civil Defense officials, and 3) A national exercise is
conducted in late May every year taking into consideration a major hurricane
hitting the Country.
The Hurricane Strikes.
Hurricane “Michelle” hit Western and Central Cuba on November 4 th, 2001. It
was indeed a major Saffir-Simpson category 4 hurricane. Maximum sustained
winds attained 220 km/h with gusts up to 250 km/h. The eye diameter was 40
kilometres wide and the diameter of Circulation was 500 kilometres.
Michelle affected 45% of Cuban territory, where 53% of the population live (5.8
million inhabitants). Economic losses were very impressive: US $ 1 866 millions.
Damage to infrastructure was also very important: 166 515 houses were
damaged, of which 12 579 were totally destroyed; 125 electric line towers and 9
TV and microwave towers fell down. TV signals were interrupted for 20 minutes
in Central and Eastern Cuba, but signals were channelled through an optic fibre
line and reception was re-establish very soon. There was great damage also
made to agriculture, i.e. 54% of sugar cane planted area was affected by the
hurricane. The total cost of recovery was US $785 million. All houses were rebuild or repaired by the end of 2002.
Conclusions:
Notwithstanding the destruction made by this major hurricane, only five people
died. This achievement was possible due to an excellent and timely forecast
and Early Warning, as well as the information and preparedness delivered by
forecasters through TV and radio since 96 hours before the strike. Also the full
co-ordination that existed with central and local government officials and the
Civil Defence, whose timely and appropriate actions and the evacuation of the
population in hazardous areas, led to only a few losses of lives and the
minimisation of material damages.
Success has been obtained also in weaker hurricanes Cat 1 or 2 and tropical
storms that have hit Cuba in the last 8 years. The number of casualties is much
less that those that happen in other countries of the region. In Hurricane “Lili”,
1996, Cat 2: no casualties; Hurricane “Georges”, 1996, Cat 1: no casualties;
Tropical Storm “Irene”, 1999,: 1 fatality; Hurricane “Isidore”,2001, Cat 1: no
casualties; and Hurricane “Lili”,2002,Cat2: 1 fatality.