The winter season of 2000-2001 began on October 9 2000 with the affectation to the Cuban archipelago of the first cold front and concluded in the second dozen of the month of April, when Cuba ceased to be under the continental anticiclonic influence that accompanied the last front of this season, which arrived on April 19 2001. On Chart 2, the mean frequency of cold front arrivals is presented per months (for 84 winter seasons) together with the behavior of these synoptic systems in the season 2000-2001. An analysis of it shows that the Cuban archipelago was affected by a total of 19 cold fronts, very close to the climatic value that is 19.7 cold fronts / season, for which it classifies as normal. 

Chart 2. Monthly mean frequency of cold fronts on the period 1916-1917 to 1999-2000 and behavior of the season 2000-2001.

Months
Period	Sept.	Oct.	Nov.	Dec	Jan.	Feb.	Mar.	Apr.	May.	Jun.	/temp
1916-17 to 1999-00	0.08	1.3	2.5	3.2	3.6	3.3	2.9	1.9	0.7	0.05	19.5
2000-2001	- - -	2	2	6	3	2	2	2	- - -	- - -	19

At the same time, in the monthly frequency for the month of December, a positive anomaly was presented in the affectation of cold fronts to Cuba so it turned out to be the month of more front activity in the whole winter season.

Fourteen CF were classified as weak and five as moderate, according to Chart 1, becoming noticeable that no strong front system affected, making already five winter seasons in a row without Cuba being affected by cold fronts of strong intensity. While for their types, twelve were classic and seven revesinos (the wind turns from South to North through the East), prevailing the first ones in the season 2000-2001. The Western and central counties of the country continue to be the most affected, as can be seen on Fig. 1.

Fig. 1. Cold fronts that affected the different counties in the winter season 2000-2001.

The influence of the dry, cold masses of air and of arctic origin, associated to the continental anticyclones, produced notable minimum temperatures in the Cuban territory, mainly in its western part. These masses of air accompanied cold fronts number eleven (January 4 20001), twelve (January 9 2001), thirteen (January 20 2001), sixteen (March 4 2001) and seventeen (March 20 2001), being responsible for the values of minimum temperature reached, which are shown in Chart 3.

 

Chart 3. Minimum temperatures registered in some towns of Cuba, mainly in their western half, in the month of January of the winter season of 2000-2001.

Day	Month	Year	Town	County	Temp. Minimum (°C)	Remarks
5	January	2001	Colón	Matanzas	5.1
			Perico	“	5.3
			Indio Hatuey	“	5.3
			Jovellanos	“	6.2
			Union de Reyes	“	7.4
			Playa Girón	“	6.7
			Sancti Spíritus	Sancti Spíritus	8.0
			Trinidad	“	9.4	It equaled the record of January 6 1984
			El Jíbaro	Sancti Spíritus	9.2
6	January	2001	Isabel Rubio	P. del Río	8.3	Notably cold this day 6, in almost all Cuba, for the influence of an arctic mass of air.
			San Juan y Martínez	P. del Río	9.9
			Güines	Havana	7.0
			Bainoa	“	8.8
			Pta. Del Este	Island of Youth	9.5
			Colon	Matanzas	7.7
			Jovellanos	Matanzas	7.6
			Santo Domingo	Villa Clara	6.8
			Yabú	V. Clara	5.1
			Venezuela	C. de Avila	6.3
			Júcaro	“	8.0
			Falla	C. de Avila	8.3
			Cayo Coco	“	11.2	Record for the month of January, for the station of Cayo Coco.
			U. de Reyes	“	7.4
10	January	2001	Güira de Melena	Havana	7.9
			Batabanó	Havana	8.4
			Indio Hatuey	Matanzas	8.5
14	January	2001	Bainoa	Havana	3.8
			Güira de Melena	Havana	5.0
			Indio Hatuey	Matanzas	5.5
26	January	2001	Batabanó	Havana	7.0
			Colon	Matanzas	6.4

Most remarkable characteristics of this season:

Cold front number five, classified as revesino by its type and of moderated intensity, arrived to the occident of Cuba in the dawn of December 4 of 2000, producing numerous rains in the whole country that ended up being intense in the oriental region, with heavy accumulates in the county of Holguín, where the following values were registered: meteorological station of Holguín, 105 mm; Antilla, 107 mm and Velazco, 101 mm. At Las Tunas, remarkable precipitation was also reported as in Las Marías with 190 mm and in La Guinea, 160 mm.

The most intense gust (80 km/h) was registered at the meteorological station of Casablanca, when cold front number 6 was affecting, on December 19 of 2000, while the minimum of 37 km/h was caused by front number two, classified as weak and revesino that affected the Cuban territory on October 14 2000.

An enlarged review deserves cold front number eight (December 23 2000), for the heavy rains that took place, that were numerous and intense. This front was classified as moderate by its intensity and revesino by its type. The arrival of this cold front to Cuba was preceded by a situation of bad weather in a large part of the country, generated by the presence and interaction of an almost stationary, zonally extended front on the Cuban territory, with strong upper jets, so that the cloudiness with slight to moderate rain, both at intervals and continuous, produced accumulates of interest in many towns of the Cuban territory. But with the arrival of the front, the contribution of baroclinic instability increased and in turn the intensity of the precipitation increased in the afternoon of the day December 23, with accumulates of more than 100 mm in towns of the north coast of Cuba. (See Chart 4). In the north of the Havana counties strong rains also took place, being Casablanca representative of these, when in the afternoon, the pluviometer registered 109 mm. The cold front continued moving towards the East over the central region of Cuba, where the intense rains also ended up being torrential, as it is shown in Chart 4. It also caused strong rains in the north coast of the oriental counties. This front remained oscillating over the central counties and Matanzas, advancing later toward the oriental end of Cuba on December 25 of 2000, where the band of clouds lost in structure and dissipation began. With the remains of this front system on the Strait of the Winds, the gradient of pressure intensified in the West of Cuba, where winds of the first quadrant were imposed, with gale force. In Fig. 2, the picture of the Meteorological Satellite, corresponding to December 23 2000, at ten in the morning is shown where the cloud cover is appreciated over Cuba.

Fig. 2. Cloudiness associated to the front cold number eight that caused abundant precipitation in Cuba.

The thirteenth front (January 20 2000) of this season was preceded by winds from the South region, with maximum speed in gusts of up to 69 km/h at the meteorological station of Casablanca, with mean value of 36 km/h.

Chart 4. Significant value of rainfall produced by cold front number eight of the winter season 2000-2001(December 23 2000).

Day	Month	Year	Town	County	Precipitation (mm/24 hours)
23	December	2000	Santiago de las Vegas	Havana	164
			Bauta	Havana	144
			Tapaste	Havana	127
			Bahía Honda	Pinar del Río	117
			El Santo, Encrucijada	Villa Clara	509
			Sitiecito	Villa Clara	306
			Cayo Coco	Ciego de Avila	321

Cold front number sixteen reminded oscillating on the western region of Cuba and produced locally intense rainfall at Varadero, with accumulates of 111 mm.

If we analyze the minimum temperatures in Chart 3, the coldest day in the winter season 2000-2001, in the western region of Cuba was January 14 of 2001, when at meteorological stations of the Havana Matanzas Plain, the thermometers registered the following values for the minimum temperature: Bainoa, 3,8(C and Güira de Melena 5,0(C, both in the Havana county and Indio Hatuey 5,5(C, in the county of Matanzas. The mean synoptic situation for this day is shown in Fig. 4, where the anticiclonic influence is appreciated on almost the whole Cuban territory.

Fig. 4. Mean synoptic situation on January 14 of 2000, coldest day for the occident of Cuba

In the month of December occurred the largest front activity, with a positive anomaly, since six cold fronts affected to the Cuban territory, classified by its intensities as four weak and two moderate; and for its types in classic (4) and revesinos (2). There have been winter seasons registered with seven CF, in the Chronology of Cold fronts (Rodríguez et al., 1984), like those of 1975-1976 and 1997-1998 (González, 2000) and others in which Cuba was not affected by any cold front in the month of December, among those is that of 1931-1932.

Only six front systems were accompanied by pre-frontal lows that caused activity of showers and storms.

Conclusions