Cyclone study

How to Track a Cyclone (For Layman)?

Cyclones Normally Occur in Three Seasons according to North Indian Ocean Climatology Study (1971-2016). Generally the Cyclone refers to a Windy Periphery with rain bands embedded in it. Let us see the Components of Cyclone in Brief.

It has major 5 Components-

1)EYE- It is the zone of Lowest Pressure. Basically well defined Cyclones have a Clear Sky in Eye Wall. The winds will be Zero at the Center. It is called the "Internal Frame of Reference". In other terms, the Moment (Angular Velocity) in the eye is zero. But relatively the Eye wall round the Eye moves very fast, thus forming a System.

2)EYE WALL- If we Moving away from Center of Cyclone, the loop of Dense Clouds (Often Cumulonimbus) surrounds the Eye of Cyclone. It contains maximum Heat potential inside it thus developing more strength in Bands and rains. In other Words it is sometimes referred as Central Dense Overcast.

A study from Dvorak revealed that-

• Cat 1 Cyclone- 10-15% round the Eye is Eye wall 
• Cat 2 Cyclone- 20-30% round the Eye is Eye wall
• Cat 3 Cyclone- Nearly 50% round the Eye is Eye wall
• Cat 4 Cyclone- Nearly 70-80% round the Eye is Eye wall
• Cat 5 Cyclone- Nearly 90-95% Round the Eye is Eye Wall

3)ZONAL WIND FIELD-The region of wind field round the Cyclone is called Zonal Wind Field Area. The Winds are maximum at this Field. This area has the potential for greater damage and effects from the Cyclone.

4)OUTER CIRRUS- It is the outer most Convective parts. Normally, the Supply of Heat transfers from Sea Surface into the Eye wall. Then after eye wall, it will be transferred around the Cyclone. But that heat wont be able to Provide Heat through out the cyclone. Hence it will Cloudy and Silent in many occasions before the start of a Cyclone day. Things change drastically when the Cyclone nears.

Tracking the Systems-

The systems can be Tracked by:

1)Weather Models

2)CIMSS Charts

Weather Models-

Global Weather Models can be prioritized for a particular basin. For our Basin, we use the Global Model Consensus, to track an approaching System. I have listed the Various Models. We can't rule out any model opinion.  

The ECMWF is the European forecasting agency Model. It is useful for Tracking the Systems under Medium Range (36-120 hours). Quite accurate and reliable to estimate the near path of Cyclone. Next is UKMET. UKMET is the British Forecast Model used by BBC channel. It is also one of the important Model for Tracking in 36-72 hours range. The Changes in the Track can be Noticed first in UKMET. In 24 hour Precipitation and Track, we can use GFS model. Quite accurate in 24 Hours. 

Convergence/Divergence in Models-

The model Consensus vary much in Long Range. Always opt the range with in 72 hours, for precise tracking. Don't go beyond 72 hours. If we see the image below, i have shown the four tracks. If the time limit is around 24 hours, the all Models showing Similar output. Its called the "convergence of Models". Models Converge at the Nearness of the event. We should have patience and observation, while giving warnings. Beyond 72 hours, the models diverge more and we cant predict an accurate track for Landfall.

LATEST "EPS" TRACK FOR A CYCLONE-

Ensemble the event-

We have the theory of Ensemble Events to increase the probability of Occurrence. For such things, we have Models like-

1)GEFS (GFS Ensembles)

2)EPS (ECMWF Ensembles)

3)Multi Model Ensemble (IMD-RMC)

4) JTWC overview (Official)

These result in much more overview of the event. We can get a greater accuracy in this Model out put than the Induvidual Models like GFS, ECMWF.

How to Track the Zone of Active ITCZ (Point of Formation of Cyclone)?

Open the NOAA Site and type MJO status. I will now guide you how to tell the MJO movement. MJO makes the Inter-Tropical Convergence Zone active and creates a pulse to spin. It is called the Vortex. The vortex slowly gets energy and separate away from ITCZ and develops into a Low pressure. Then if conditions favour much, it will be called as a cyclone.

Latest Forecasts Shows the MJO will move into Western Pacific and after some days, it will re-emerge into Africa.

Steps to be Followed to Track the Cyclones-

• Open Tropical Tidbits site or any other Paid models site like Weather Bell, Accu Weather Pro
• Make the present analysis and just slide the Model data for 24 hours overview
• Next note the developments.
• If you still have doubt, tap to see for next 72 or 120 hours. If the Model output shows any active rainfall or flow of winds, mark that area.
• Finally watch the same model output in your free time for about 2 days and finalize.