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Weather conditions and winds on the Adriatic sea

Weather conditions and winds on the Adriatic sea

On the Croatian side of the Adriatic Sea, there are three characteristic types of weather which can generally be distinguished: by the south wind - the southern warm and moist wind called Jugo, by the north wind - with the northern cold and dry wind called Bura, and by the stable summer weather, with daily NW - northwest wind called Mistral and the night breeze from the mainland called Burin. Winds Jugo and Bura are the main weather features on the Adriatic, and they blow more often in the winter period (from October to April), and the Mistral blows mostly in the summer. Jugo is stronger and it is more frequent in the southern Adriatic, and Burin is more frequent on the northern Adriatic. The winter winds are generally more frequent, longer-lasting and stronger than the summer ones. A change in the wind from the south Jugo wind to the north Bura wind may be dangerous for the inexperienced and uninformed boaters, whether at sea, or an unsafe anchorage or a port.

BURA

Bura is a sudden, gusty, dry, cold and sometimes hurricane-strong wind (up to 12 Bf). It blows in extraordinarily violent blows (i.e. REFUL) from the cold east Adriatic coastline, mostly from the NNE to ENE direction. The configuration of land affects the strength and direction of the wind. Strong Bura savagely crushes on the sea surface; the waves are irregular, steep, short and low. Strong Bura disperses the tops of the waves into the sea foam and carries it as dust ( "sea smoking"), which reduces the visibility, and it represents a risk is for the sailors because it interferes with breathing. If there is no sea ​​dust, the visibility is good. The air temperature can decrease in a short period of time for 10 degrees Celsius even. Usually the pressure is increased. The frequency and severity of Bura decreases from the north to the south-east coast of Croatia. Bura blows more often, more strongly and longer (3-7 days) in the winter, and rarely, weakly and shortly in the summer, (up to 2 days). In proportion to the distance from the mainland, Bura gets weaker, and with less impact, but with stronger waves. The sudden appearance of this Bura wind is one of its most dangerous features. Bura is the strongest around 10 a.m., and between 6 p.m. and 10 p.m. It weakens around noon and midnight.

We distinguish anticyclonic and cyclonic Buras or storms. The anticyclonic Bura storm occurs in dry and clear weather, accompanied by high pressure, strong and gusty wind blows blowing from the NW to N direction, with moderate cold. The cyclonic - dark "Skura" Bura is a very strong or "constant" wind without significant wind blows, blowing from the direction NE-E. It is followed with the cloudy and rainy weather in winter and sometimes snow with a sudden drop in pressure. Places where Bura storm blows strongest and most often are: Gulf of Trieste, Lim Canal, Rijeka bay, Velebit Canal (Senj - Karlobag), Šibenik area, near Split and Solin, Vrulja bay (Makarska Riviera), the Neretva delta and Zuljanski bay (Peljesac). The following rule applies: the bare sides of the island towards the coast are particularly exposed to the Bura wind blows. A typical omen sign of the Bura is the formation of whitish clouds called "caps" or "crowns" on the top of the mountains, especially over the Velebit and Biokovo mountains, the increase in air pressure and the drop in temperature. The edge of the lower mass of clouds is horizontal and clearly delimited. If the "cap" is growing it means that the storm is growing stronger, and vice versa. After the strong Bura wind ends in the summer, nice weather can be expected for a few days, as a rule, with a moderate breeze. Bura is the strongest and most dangerous wind for sailing, due to its sudden appearance and rapid development.

TRAMONTANA – NORTH WIND

Tramontana (Tramuntana) is a form of Bura blowing approximately from the north (N). It is a local, cold, dry, short-lived and gusty wind as Bura wind. It is followed by clear skies and high barometer pressure. Away from the coast it is stronger, lasts longer and generates developed waves. It is more common in the southern Adriatic.

LEVANT (LEVANAT) – EAST WIND

Levant – east wind is the form of Bura wind blowing from the E direction. It blows shortly, steadily and moderately strongly. This is a transitional wind when Jugo wind becomes Bura wind, or vice versa. In winter, it is followed by rain and moderately cold weather, and sometimes it brings snow with it. In the summer, in the morning, during the sunny and stable weather, it blows along the canals between the Dalmatian islands. This wind is a unique wind blowing in the northern Adriatic. It favors the navigation.

JUGO SOUTH WIND

Jugo is a warm and moist wind, with equal speed and steady in direction. It blows mostly from ESE direction to the S direction. It is less dangerous than the Bura wind, because it comes gradually, blows steadily, and reaches the stormy strength only on the second or the third day of blowing. It blows more frequent and stronger in the south Adriatic than in the north Adriatic. It blows rarely and with reduced intensity in the summer, and it lasts no longer than 3 days. In the winter, it can take up to 10 days, and with less disruption even to 3 weeks. We distinguish anticyclone Jugo and cyclone Jugo winds. The anticyclone – clear weather Jugo keeps blowing with bright and sunny days and little cloud cover, and with warm and humid weather. It is more common in the spring and autumn. Mostly, there is no precipitation, or even light rain is sometimes possible. The atmosphere is murky and the visibility is poor. It is preceded by a rise in the barometric pressure. Jugo more often transits into the breeze blowing from the S and SW directions, rather than into the breeze blowing from the E direction. The omen signs of the Jugo south wind: the haze and clouds in the SE and S horizons, the temperature and humidity rise, while the air pressure gradually drops. The cyclonic - "dark" Jugo is characterized by thick, low, leaden-gray clouds, and heavy, persistent rain. Sometimes it blows in gushes. The atmospheric pressure is low, the rough sea decreases the visibility. It blows more often than the anticyclonic Jugo south wind.

LEBIC (GARBIN) – SOUTHWEST WIND

This is a storm weather of the SW direction with very advanced waves and heavy precipitation and poor visibility. It rarely blows on the Adriatic coast of Croatia, and it is especially strong during the winter and autumn. In the summer, it is a local wind Nevera (Lebicada) and it lasts briefly. It is more common in the central and southern Adriatic. Lebic wind creates rough seas and in the summer it lasts only for a few hours. The omen sign of the Lebicada wind is the low fog lines on the southwestern part of the horizon, a sudden drop in pressure and extremely high tides. Due to the sudden occurrence of the rough seas it is dangerous for vessels in ports that are not protected against the SW wind blows.

PULENTO – WEST WIND

Pulento blows from the W direction. It starts suddenly, and it occurs seldom. Pulento is weak, short-lived, cold and dangerous wind with the strength of up to 12 Bf. It may cause wavy sea along the west and south-west coast of the outer islands and in the sea canals. It brings short but abundant rain. After Pulento, the weather improves for a short period of time, and the wind again transits into the Jugo south wind. It is more common in cold seasons than in the warm seasons. Along the Croatian coast of the Adriatic Sea it creates big waves and difficult sea. The atmospheric pressure is low.

MAESTRAL - BREEZE

Maestral is a daily wind typical for the summer period (April - October). Depending on the local conditions, it blows from the NW to SW direction. It is a pleasant and refreshing wind of the mild to moderate strength. The barometric pressure is low. It moderates the summer heat, it follows the nice and stable weather. It is pleasant for sailing. It is stronger and more frequent in the southern and central Adriatic than in the northern Adriatic. It blows stronger in canals. The waves are high on the high seas. It starts blowing around 9-10 a.m. as a soft breeze, and around 2 p.m. it reaches its maximum, and it ends before the sunset. From morning to afternoon it changes its direction of blowing more towards the right, i.e. it follows the sun from the southwest to the northwest direction.

 

BURIN

Burin - blows during the summer nights from the mainland towards the sea. It begins to blow after the sunset. Its direction in the northern Adriatic is from NNE to ENE, and in the southern Adriatic its direction is more from the E direction. It brings nice weather, and high barometer pressure.

 

NEVERA -  BAD WEATHER

Besides the local winds, local and short-term bad weather events of smaller scale – such as Nevera or Neverins occur at the Adriatic Sea. They occur in all seasons but they are more often in the summer. Summer Nevera storms are more frequent in the northern Adriatic than in the south Adriatic (and vice versa in the winter). The highest number of Nevera storms comes from Italy, especially from its northern part and cross the Adriatic from the direction of SW to NW at high speed. The Nevera storms are characterized with strong and dangerous wind blows (up to 10 Bf), usually heavy rain, lightning, thunder, and the temperature drops. The Nevera storms are short, lasting up to 2 hours, and they occur most often in the early evening and at night. After the Nevera storm, the weather is usually quiet and clear. The omen signs of the Nevera winds: hot and humid weather, stillness, drop in the atmospheric pressure. Dark storm clouds appear in the West, and move towards the east, carrying lightening. When the Nevera storm approaches, the thunder can be heard. The decrease in the time interval between the flash of lightning and the sound of the thunder bolt signifies the approaching of the Nevera wind. Before the approaching of the Nevera wind, the anchored vessels must be specially protected against its impact, because the Nevera wind appears suddenly and its severity is very dangerous.

 

OMEN SIGNS FOR THE LOCAL WEATHER FORECAST

 

SOME OMEN SIGNS OF THE WEATHER AGGRAVATION

  • The drop in the atmospheric pressure
  • The occurrence of extreme high tides
  • The absence of maestral in the summer or if maestral stops blowing before time
  • The pale Moon and a wreath (ring) around it predicting the change in weather
  • The red skies or rainbow early in the morning announcing the soon rain
  • The winter maestral is often a sign of the Jugo wind and the rain
  • The strong wind in the morning with clear skies
  • The transit of the Bura wind towards the E direction during the clear weather, especially towards the SE direction
  • The constant low pressure during bad weather means that the weather condition will last

SOME SIGNS OF THE WEATHER IMPROVEMENT

  • A gradual increase in pressure, especially above 1012 hPa
  • The appearance of clear weather in the overcast sky on the W part of the horizon
  • The principle is: the wind after rain brings nice weather
  • The appearance of redness after the sunset on the clouded sky

 

SOME SIGNS FOR THE CONTINUED GOOD WEATHER

  • Maestral during the day, and Burin at sunrise (and at night)
  • Extremely low water level (low tide), or if the changes in the tides during the day are regular, and if the sunset is clear during the clear weather, and lits up the skies until its very setting, and if illuminates the western horizon in beautiful colors after the sunset ("red skies")
  • If the high atmospheric pressure does not change, or if it increases
  • The skies are clear and the weather is still (with the occasional cloud)
  • While the Bura wind blows, there is no worsening of the bad weather

VISIBILITY - FOG

Visibility is the greatest horizontal distance (in km) at which one can see and recognize objects (during the day) or light (at night). Visibility on the Adriatic Sea is relatively large (20-30 km). The fog reduces the horizontal visibility to less than 1 km. When the visibility is between 1 and 10 km, such a blurred visibility is called a haze. Classification of fog: Thick fog, visibility up to 50 m; Moderate fog, visibility up to 500 meters; Low fog, visibility up to 1000 m. The frequency of fog on the Croatian Adriatic coast is low and it is more common in autumn and winter. The fog is more common in the northern Adriatic (over 20 days a year), its frequency in the central Adriatic is 5 days, and in the southern Adriatic it is 1-2 days a year.

WIND ROSE


BEAUFORT SCALE

 

Speed

wave hight

km/h

m/s

kt

mph

m

ft

0 Bf

calm

< 1

0-0.2

< 1

< 1

-

-

1 Bf

light air

1-5

0.3-1.5

1-3

1-3

0.1(0.1)

0.25(0.25)

2 Bf

light breeze

6-11

1.6-3.3

4-6

4-7

0.2(0.3)

0.5(1)

3 Bf

gentle breeze

12-19

3.4-5.4

7-10

8-12

0.6(1)

2(3)

4 Bf

moderate breeze

20-28

5.5-7.9

11-16

13-18

1(1.5)

3.5(5)

5 Bf

fresh breeze

29-38

8.0-10.7

17-21

19-24

2(2.5)

6(8.5)

6 Bf

strong breeze

39-49

10.8-13.8

22-27

25-31

3(4)

9.5(13)

7 Bf

high wind

50-61

13.9-17.1

28-33

32-38

4(5.5)

13.5(19)

8 Bf

gale

62-74

17.2-20.7

34-40

39-46

5.5(7.5)

18(25)

9 Bf

strong gale

75-88

20.8-24.4

41-47

47-54

7(10)

23(32)

10 Bf

storm

89-102

24.5-28.4

48-55

55-63

9(12.5)

29(41)

11 Bf

strong storm

103-117

28.5-32.6

56-63

64-72

11.5(16)

37(52)

12 Bf

hurricane

>=118

>=32.7

>=64

>=73

14(-)

45(-)