Friday, October 11, 2013


Akshay Deoras
Severe Weather Forecaster


Beating all the expectations, Cyclone Phailin yesterday (11th Oct) morning intensified to a Category 4 cyclone and had a peak winds of 135 kt as per JTWC which gusted even above 150 kt during the morning hours. The estimated air pressure at the core too had dropped to around 925mb-930mb. Morning images clearly showed an eyewall surrounding the eye and Phailin was all set to replace its existing eye with the eyewall- a process common in such high intensity cyclones which is called as "Eyewall Replacement Cycle". The maximum winds in such a high intensity cyclone are in the
eyewall and as it moves inwards towards the eye, the cyclone typically weakens which is usually indicated by the increase in the air pressure of the core and decrease in the wind speed. Although with Phailin, we couldn't avail sufficient data to demonstrate how much the wind speed decreased or air pressure increased.

(Image at Right obtained in the late afternoon showed the completion of eyewall replacement cycle)

As soon as the new eye got stabilised, Category 4 cyclone Phailin re-intensified to a powerful Category 5 cyclone and at the moment continues to be a category 5 cyclone with estimated max sustained winds of around 146kt (around 270km/hr),gusting to over 320km/hr and an air pressure of around 915mb at the core as per NRL. Over the past few hours, Tropical Cyclone Phailin has become faster as it moved North-West with a speed of around 17km/hr from the previous 10km/hr which was yesterday morning. The latest attached imagery (the top image) clearly shows a stable eye and a CDO feature (Central Dense Overcast : a feature in which large band of thunderstorms in various shapes, here circular surround the eye) and typically the Dvorak intensity decreases
(say T ~5).


Right- The latest CIMSS image of SST (Sea Surface Temp) of Bay of Bengal shows a pool of unusually warmer sea offshore Odisha,Andhra Pradesh having SST of 30C as against 29C where Phailin's heat engine (the core) is at the moment. Thus its likely that as Phailin moves NW further towards the coast for a landfall, its intensification will continue given this support. Phailin has enjoyed light sheared environment of just 5-10 Kt that has hardly spoilt its intensity (apart from broken symmetry to its SW spiral arms around yesterday when they were in a moderate shear region of 25-30Kt).

The air dynamics too have been favourable for this system with the upper air divergence now better than the yesterday morning : during the eyewall replacement when it had dropped to 30 kt. Although it continues to be numerically the same, a drop (cooling) of cloud tops are indicating a better southward radial outflow and a better symmetrical structure thanks to the assisted 40 kt lower air convergence which too had dropped to 30 kt for a while leading to a kind of fragmented spiral arms of the system leading to the broken symmetry today (short before it being declared as a category 5)

TPW (Total Precipitable Water) continues to be very impressive with a numerical value of over 65mm suggesting a very high flooding threat for coastal,interior Odisha apart from significant
rainfall in Eastern India (see METD WEATHER map for details) which covers states like Jharkhand,Bihar,West Bengal prominently.

(Right- CIMSS TPW image showing high PW)

So it looks like Tropical Cyclone Phailin will continue to move NW towards Odisha coast with more or less the same intensity till the landfall (although some models indicate it to be a higher end of Category 4 cyclone at the landfall). The reason being attributed to this is the proximity of land and subsequent interaction with the dry air just before the landfall.

The area of landfall should be around Brahmapur in Odisha rather Gopalpur (which comes more close to the sea than the former). The region of landfall like conditions should bounce between Srikakular,AP to Puri,Odisha with the highest chances towards Brahmapur region and the landfall (eye crossing the land) will be towards today evening (ALTHOUGH LANDFALL LIKE CONDITIONS WILL BEGIN FROM THE LATE MORNING TO AFTERNOON ONWARDS) 


* As the cyclone approaches the coast, there will be an increase in the sea waves height as the storm surge (movement of wall of sea water towards the land as the cyclone moves inward). 

*Rainfall along with wind speed will gradually increase in Odisha state including bordering states like coastal Andhra Pradesh, coastal West Bengal. Big cities like Puri,Cuttack,Bhubaneshwar etc will witness high velocity winds,rains in the day and conditions turning worst from the afternoon onwards. 

* Due to increased rainfall and wind, the first damage will be to the weak settlements like huts etc and breaking of trees (uprooting too) with damage to powerlines will start.

* During the landfall, the coastal areas of Odisha and areas around Srikakulam,AP will witness strong tides of height upto 20ft and wind having velocity of around 230km/hr and above (gusting more than that). Interior areas too will start witnessing such conditions along with heavy rains.

* Widespread disruptions to rail,road and air traffic in the state are likely from today. Due to flood in many areas due to the rains, villages etc will get cut off from nearby cities/towns. Severe waterlogging too will be witnessed in big cities like Bhubaneshwar and around. 


  • Listen to the radio or TV for information.
  • Secure your home, close storm shutters and secure outdoor objects or bring them indoors.
  • Turn off utilities if instructed to do so. Otherwise, turn the refrigerator thermostat to its coldest setting and keep its doors closed.
  • Turn off propane tanks
  • Avoid using the phone, except for serious emergencies.
  • Moor your boat if time permits.
  • Ensure a supply of water for sanitary purpose such as cleaning and flushing toilets. Fill the bathtub and other larger containers with water.
  • Find out how to keep food safe during and after and emergency.
You should evacuate under the following conditions:
If you are directed by local authorities to do so. Be sure to follow their instructions.
  • If you live in a mobile home or temporary structure – such shelter are particularly hazardous during hurricane no matter how well fastened to the ground.
  • If you live in a high-rise building – hurricane winds are stronger at higher elevations.
  • If you live on the coast, on a floodplain, near a river, or on an island waterway.
If you are unable to evacuate, go to your wind-safe room. If you do not have one, follow these guidelines:
  • Stay indoors during the hurricane and away from windows and glass doors.
  • Close all interior doors – secure and brace external doors.
  • Keep curtains and blinds closed. Do not be fooled if there is a lull; it could be the eye of the storm – winds will pick up again.
  • Take refuge in a small interior room, closet or hallway on the lowest level.
  • Lie on the floor under a table or another sturdy object.
  • Avoid elevators.