Thursday, October 10, 2013

Cyclone Phailin undergoes rapid intensification, now a Category 3 cyclone!

Akshay Deoras
Severe Weather Forecaster


Surpassing all the anticipations, Tropical Cyclone Phailin has undergone (and continues to undergo) a rapid intensification due to which in a very short time it has intensified to a powerful Category 3 Cyclone with maximum winds of around 100Kt (around 185km/hr) gusting to around 125Kt and cloud top temperature over -70C with a clearer eyewall!!!!

The above image of Cyclone Phailin from NRL clearly shows a stable eye and possibly the associated eyewall close to 16N,90E as Phailin continues to move NW towards the Odisha coast.

The major reason of this rapid intensification of Cyclone Phailin is the absence of the conditions (on high magnitude) (like dry air, cooler sea surface temperature,high vertical wind shear etc). Such conditions often interfere with the strength of a cyclone leading to its weakening. With Tropical Cyclone Phailin, the conditions have been supporting for it to intensify since the beginning.

Upper Air conditions continue to indicate that Tropical Cyclone Phailin is getting a very favourable southern outflow ranging over 30 Kt assisting the convection process whereas its being "gripped/tightened" due to the extremely favourable convergence ~30Kt at its base to the south of non CDO (Central Dense Overcast) eye. Wind shears to continue to be relaxed just 5-10Kt near the LLCC (Low level circulation centre) and continue to be moderate to the SW (seen from the broken fragments) although it is not affecting the cyclone's strength. The CIMSS wind shear tendency continues to show that Phalin will continue to enjoy a light sheared environment enroute to Odisha coast thereby nailing down its chance to weaken significantly.

The above multi sensitivity image from NRL (refer bottom two) clearly show the symmetrical rainbands (pointed by yellow arrows) around the eye and the stable eyewall circulating the eye. Hence one can't expect an eyewall replacement cycle soon in Phailin. The temperature of the eye of Phailin has risen to 0C also (Courtesy-Rajesh Kapadia/Vagaries of Weather) which is a usual feature with such high intensity cyclones which happens when the air in the eye gets adiabatically compressed (during its sinking stage) leading to a rise in the temperature. The MSLP in eye area is anticipated to be around 950mb!

As Phailin continues to churn in a warm (29C) SST of Bay of Bengal, not even the dry air (encircled in red in the above image) offshore West Bengal will affect its intensity as the inflow isn't from northern direction.

Considering all the parameters, Tropical Cyclone Phailin is now expected to intensify (JTWC estimate) to a Category 4 Cyclone shortly before it hits Odisha coast : Near Brahmapur on Saturday (12th Oct 2013) afternoon period (Although landfall like conditions will emerge from the evening/night of Friday,11th Oct ONLY) 

It looks like max sustained wind of this cyclone at the landfall on Saturday will be around 110kt (around 200km/hr) which will be categorised as a high end Category 3 Cyclone (Although on Friday,11th Oct its likely to intensify to Category 4). As it approaches Odisha (although landfall like conditions will happen in Odisha bordering Andhra Pradesh coast like Srikakulam), the outer convection bands will encounter with the land and so there should be a decreasing intensity (A degradation from Category 4 to Category 3) but be it Category 3 or 4, Tropical Cyclone Phailin posses a MAJOR threat for Odisha which includes widespread damage to life,property

Jharkhand,Western West Bengal also posses heavy rainfall threat due to it along with Odisha on Saturday,Sunday chiefly. 

* The big city coming in this threat will be Bhubaneshwar in Odisha where high velocity winds (gusting possibly upto 200km/hr ) with heavy rains will be witnessed during the landfall.


Before a Cyclone (Hurricane)

To prepare for a hurricane, you should take the following measures:
  • To begin preparing, you should build an emergency kit and make a family communications plan.
  • Know your surroundings.
  • Learn the elevation level of your property and whether the land is flood-prone. This will help you know how your property will be affected when storm surge or tidal flooding are forecasted.
  • Identify levees and dams in your area and determine whether they pose a hazard to you.
  • Learn community hurricane evacuation routes and how to find higher ground. Determine where you would go and how you would get there if you needed to evacuate.
  • Make plans to secure your property:
  • Cover all of your home’s windows. Permanent storm shutters offer the best protection for windows. A second option is to board up windows with 5/8” marine plywood, cut to fit and ready to install. Tape does not prevent windows from breaking.
  • Install straps or additional clips to securely fasten your roof to the frame structure. This will reduce roof damage.
  • Be sure trees and shrubs around your home are well trimmed so they are more wind resistant.
  • Clear loose and clogged rain gutters and downspouts.
  • Reinforce your garage doors; if wind enters a garage it can cause dangerous and expensive structural damage.
  • Plan to bring in all outdoor furniture, decorations, garbage cans and anything else that is not tied down.
  • Determine how and where to secure your boat.
  • Install a generator for emergencies.
  • If in a high-rise building, be prepared to take shelter on or below the 10th floor.
  • Consider building a safe room.

During a cyclone (hurricane)

If a hurricane is likely in your area, you should:
  • 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.

No comments:

Post a Comment