Cyclone Luban Detailed Update & Analysis: 

After the potential convergence increases, the cyclonic circulation was formed near off the coast of Kerala by late Thursday, 4th October 2018; which later continued intensifying into Low Pressure Area (LPA) during next 24 hours of its formation which then was named “Invest 99A” temporarily as being under observation.  The anti-clockwise circulation firstly moved slightly west-northwestward, intensifying gradually into Well Marked Low (WML) then turning into Depression by Saturday, 6th of October (moreover the alert has been issued for Kerala coasts as Depression forms).

 

The prominent parameters & factors are clutching the forecast that the Depression lying in Southern Arabian Sea would intensify into Deep Depression in next 24 hours. On balancing the both major ‘optimistic & pessimistic parametric conditions’ indulging changes in Sea Surface Temperature (SST), Convergence, Vertical Wind Shear, Indian High Pressure Area (HPA) and Western Disturbance’s Influence due to Dipping etc; factors are combinedly pointing towards the phenomenon of early intensification of Deep Depression into Tropical Storm in next 32 – 36 hours, which would then be named as “Cyclone Luban

 

Effects of Constitutive ‘Optimistic & Pessimistic Parametric Conditions’

 

The ‘Path & Strength’ of anticipated Cyclone Luban is being the ‘hot topic’ under discussion from past week as several analysis has been experienced over PakWeather.com’s Facebook Page. Major constituents having positive/optimistic or negative/pessimistic effects on ‘cyclone’s path & strength relative to Pakistan’s coast are being individually mentioned undergo;

  •  Movement/Direction Detection: Under the influence of HPA lying in SE of circulation, it firstly slightly moved northward, then westward, and is now moving in WNW  of direction; however as the area of convergence extending more upward (NW) and latest satellite images study proves its movements to be in NW direction (40%) towards Oman region affiliated with Pakistan’s Balochistan
  • Sea Surface Temperature (SST): The SST, where the Depression Invest 99A lies off the coast of Kerala, is ranging between 28.8°C – 30°C; which is an ideal temperature for Cyclone’s formation, while the SST near Sindh-Gujrat coast averages about 29°C, still on increasing trend. Hence Oman-Yemen’s SST is lying from 27°C – 28°C. The scenario supports the strengthening of Depression into CAT-2 Cyclone in next 48 – 52 hours. It would may upgrade its category while travelling in Sea.
  • High Pressure Ridge Extending into North Arabian Sea: The main reason behind ‘anticipating’ System’s movement more in westward direction than Northward is due to the under-observation formation of High Pressure Area, along with Cyclone’s formation, on mid-level over Sindh-India region. HPA would be pushing Cyclone AWAY from Indian & Pakistani Sindh Coast, which may result in its landfall in Oman, however in case of re-curving it may lose strength gradually moving in N or NE direction (due to WD influence)  or even dissipating without putting any effect on Pakistan’s coast. However if, under the conditions, the Indian HPA is formed slight eastward or its ridges are limited to Indian region only then we can expect big changes in Cyclone’s track, which then can lead Cyclone towards Pakistan’s coast (continuously more intensifying due to good SST, exceeded convergence and low wind shear level, more likely chances are 30%).
  •  Schedule of Western Disturbance Arrival: Back to Back WDs ‘loaded with western moisture’ are invading Pakistan region, hence the systems are expected to withdraw at the same time when the Cyclone would may have been intensified into Cat-2/Cat-3 by 9th of October, leaving the ‘dry air mass‘ in Pakistan, Iran and Arabian Peninsula region which can cause hurdle in further Cyclones intensification, although an induced UAC may also develop over Sindh-Balochistan region; however increase in SST and support of Eastern Moisture would may balance the strength of cyclone till its landfall.  Another trend of WD’s arrival is anticipated from 12th of October (+/- 1 day) which can then attract the weaken cyclonic circulation towards Pakistan’s coast.
  • Mean Sea Level Pressure: The MSL Pressure is already on decreasing trend and would be much decreased by 9th of October, causing (wave) disturbance in whole Arabian Sea region; thus the warning is being issued for India, Pakistan, Oman, Srilanka and Somalia coasts to preserve their countrymen going into open sea area.

Conclusion:

The Depression Invest 99A shall be converted into Deep Depression turning into Tropical Cyclone of Cat-1 in next 48 – 52 hours, initially moving into WNW, slightly NW direction. While upon dependent on factors it would continuously be gaining strength despite of its movement in any direction, thus the maximum strength of cyclone is anticipated between Cat-3 to Cat-4. The track of cyclone would vary to all extents because of continuous fluctuation in HP ridges and timings of WD dipping, however it would intensify much more if moved towards Sindh-Balochistan rather than Oman-Yemen due to expected SST statics. The conditions required for cyclone to move towards Pakistan coasts (Northward, NE)  are dependent on early arrival of WD  and the HP’ ridges to get limited to its extent in Indian region.

 

Chances of Cyclone Luban to make Landfall in Oman are +70% while chances to re-curve  before making landfall ‘with sustained strength’ towards Pakistan’s Coast are less than 30% 

 

 

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Analysis on Cyclone Luban’s Effects on North Arabian Sea
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Haider Saqib

Posted by Haider Saqib

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