1.5.6 Low pressure and Cyclone Alerts

These are specially given by the India Meteorological Department. Expected wind speed and direction in oceans and land, fishermen warning, and district wise colour coded rain warning are included in it. There are chances that the low-pressure area strengthens to form a cyclone. Hence low-pressure area warnings should be treated carefully.

Unlike before, the formation of low-pressure areas and cyclones seem to increase in the Arabian Sea also. Apart from that, those forming in the Bay of Bengal and The Indian Ocean also results in heavy rain and wind in Kerala. Cyclones are formed during the months from April to December north of the equator in the Indian Ocean. May to November is the period in which cyclones are more likely to form.

The process of formation of the cyclone from the low-pressure area is divided into 8 types based on wind speed around the low-pressure area.

1. Low-pressure area: An area enclosed by a closed isobar with minimum pressure inside when the mean surface wind is less than 31 kmph

2. Depression: A cyclonic disturbance in which the maximum sustained surface wind speed is between 31 kmph and 61 kmph

3. Deep depression: A cyclonic disturbance in which the maximum sustained surface wind speed is between 50 kmph and 61 kmph

4. Cyclonic storm: A cyclonic disturbance in which the maximum sustained surface wind speed is between 62 kmph and 88 kmph

5. Severe Cyclonic Storm: A cyclonic disturbance in which the maximum average surface wind speed is in the range of 89 kmph to 117 kmph

6. Very Severe Cyclonic Storm: A cyclonic disturbance in which the maximum average surface wind speed is 118 kmph to 166 kmph

7. Extremely Severe Cyclonic Storm: A cyclonic disturbance in which the maximum average surface wind speed is 167 kmph to 221 kmph

8. Super cyclonic storm: A cyclonic disturbance in which maximum wind speed is 222 kmph and above

A cyclone warning is given in 4 stages. Separate bulletins will be released by the India Meteorological Department.

1. First Stage - Pre Cyclone Watch: The first bulletin which mentions about the chances of depression developing into a cyclone. It is released 48 hours prior to the formation of rough weather in the coastal regions which may be influenced by the cyclone. This bulletin will contain the following.

  • The land areas where rough weather may be experienced due to the influence of the cyclone.

  • The areas where rough sea may be experienced.

  • Analysis of the next 72 hours.

  • An immediate warning should be issued to prevent fishermen from venturing into the areas of the sea mentioned in the bulletin.

2.Second Stage - Cyclone Alert: The second bulletin which mentions about the chances of depression developing into a cyclone. It is released 48 hours prior to the formation of rough weather in the coastal regions which may be influenced by the cyclone. This bulletin will contain the following.

  • The expected intensity of the cyclone

  • Predicted path of the cyclone

  • In what all places at what all timings will the different stages of the low-pressure area developing to a cyclone will pass through

  • Land areas likely to feel rough weather due to the influence of the cyclonic storm

  • The areas where rough sea may be experienced.

  • Warnings to fishermen, media, disaster relief workers and public regarding weather and sea conditions

  • Analysis of the next 72 hours

  • Fishermen should not be allowed to venture into parts of the sea where the influence of the cyclone is expected to be felt

  • Measures should be taken to evacuate people from land areas where the influence of the cyclone is expected to be felt in consultation with the S.E.O.C

3.Third Stage - Cyclone Warning: The third stage bulletin is released 24 hours prior to the formation of rough weather in the coastal regions which may be influenced by the cyclone. This bulletin will contain the following.

  • Present Intensity of the cyclone

  • The present location of the cyclone

  • When and where the landfall of the cyclone will occur

  • Land areas likely to feel rough weather due to the influence of the cyclonic storm

  • The areas where rough sea may be experienced

  • The intensity of rain in various areas where the influence of the cyclone is experienced

  • Areas susceptible to coastal erosion

  • The predicted direction of wind after landfall

  • In what all places at what all timings will the different stages of reduction of the intensity of the cyclone will occur

  • Analysis of the next 72 hours

  • Warnings to fishermen, media, disaster relief workers and public regarding weather and sea conditions

  • Fishermen should not be allowed to venture into parts of the sea where the influence of the cyclone is expected to be felt

  • Measures should be taken to evacuate people from land areas where the influence of the cyclone is expected to be felt in consultation with the S.E.O.C

4.Fourth Stage - Post Landfall Outlook: Usually the intensity of the cyclone decreases after landfall. This bulletin which is released 12 hours prior to landfall will contain the following

  • Present Intensity of the cyclone

  • The present location of the cyclone

  • When and where the landfall of the cyclone will occur

  • Land areas likely to feel rough weather due to the influence of the cyclonic storm

  • The areas where rough sea may be experienced

  • The intensity of rain in various areas where the influence of the cyclone is experienced

  • Areas susceptible to coastal erosion

  • The predicted direction of wind after landfall

  • In what all places at what all timings will the different stages of reduction of the intensity of the cyclone will occur

  • Analysis of the next 72 hours

  • Warnings to fishermen, media, disaster relief workers and public regarding weather and sea conditions

  • Fishermen should not be allowed to venture into parts of the sea where the influence of the cyclone is expected to be felt

  • Measures should be taken to evacuate people from land areas where the influence of the cyclone is expected to be felt in consultation with the S.E.O.C

  • Make sure that emergency disaster relief arrangements are in place in areas through which the cyclone is passing through and the influence of the cyclone is expected to be felt

The Indian Meteorological department will start issuing bulletins from Depression/Deep Depression stage. The bulletins will be issued at the following times:

• Midnight at 12

• 3 AM

• 6 AM

• Noon at 12

• 6 PM

Once the cyclone is fully developed bulletins will be issued at the following times:

• Midnight at 12

• 3 AM

• 6 AM

• Noon at 12

• 6 PM

• 10 PM

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