"Cyclone Lehar" ingests dry air, weakens as per the expectation

METD WEATHER
Akshay Deoras
Severe Weather Forecaster

***UPDATED***

0928am IST,28th Nov 2013- Former Cyclone Lehar weakens to a Tropical Depression and shall be striking AP as a weak Tropical Depression........ 

It turned out to be a a very major day for Cyclone Lehar as it behaved completely against the forecasts...however obeyed METD WEATHER's forecast. The dry air which it pulled from Eastern India finally started showing its effect from yesterday night as it put a lid on the intensity of the cyclone. Cyclone Lehar's central core became very unstable since last night which continued till today afternoon where the CDO (Central Dense Overcast) feature vanished which allowed the LLCC (Low Level Circulation Centre) to appear in some of the IR satellite images obtained today morning. As of now, we are waiting for JTWC update on the max winds of Cyclone Lehar which shall be a Tropical Storm Lehar now given the fact that its maximum sustained winds should be on the borderline of Tropical Storm and Category 1 as per the Saffir Simpson Scale where from 64kt onwards (119km/hr), systems are rated as Category 1 and below that till 35kt (63km/hr), the system is a Tropical Storm...

Lets have a look at how dry air killed/chocked the system: Category 1 Cyclone LEHAR

Above image is the CIMSS TPW (Total Precipitable Water) image of yesterday which clearly shows how much the dry air had increased around the western quadrant of Cyclone Lehar. Due to some reasons, this dry air wasn't entering the circulation centre which actually is the thermal engine driving the entire system.

Above is the IR NHC image of yesterday morning which showed how stable the centre was in comparison with the below image of today afternoon when the system started showing first signs of weakening on rapid scale. Below image clearly shows a rapid warming of the central core- a typical indicator of increasing cloud top temperature (Present peak cloud top temperature is about -40/-50C as against -70/-80C which was today morning/yesterday)... Dry air ingestion does such thing causing temperature inversion which ultimately inhibtis the growth of CB clouds and weakens the system.

Below is the latest IR NHC CIMSS image of supposed Tropical Storm Lehar as CIMSS is showing. Now comparing the above and below image, one can infer how rapidly the system is disintegrating..

Dry air ingestion/wrapping around the system can be seen from this latest TPW image. Notice how the dry air is wrapping around most of the system and its thermal content has decreased (has become less shaded brown)... In the coming period, dry air will wrap more, ingest more and practically it will completely disintegrate the system

So what will happen now? 

As a Tropical Storm, Lehar will hit Andhra Pradesh coast around Machilipatnam tomorrow,28th Nov 2013 morning period- stretching to afternoon also. Given the disintegration rate, it seems Lehar will hit the coast at a max sustained winds of 45-50kt around 90km/hr... gusting to around 100km/hr or so.. The landfall zone shall stretch between Machilipatnam and Kalipatnam (AP) 

Heavy rains will be witnessed in these areas and probably the storm surge will be around 3-4feet. 

HERE IS WHAT PEOPLE MUST DO (Via BOM,Australia) 

When a cyclone warning is issued (For Andhra Pradesh coastal areas) 

Depending on official advice provided by your local authorities as the event evolves; the following actions may be warranted.

• If requested by local authorities, collect children from school or childcare centre and go home.
• Park vehicles under solid shelter (hand brake on and in gear).
• Put wooden or plastic outdoor furniture in your pool or inside with other loose items.
• Close shutters or board-up or heavily tape all windows. Draw curtains and lock doors.
• Pack an evacuation kit of warm clothes, essential medications, baby formula, nappies,
  valuables, important papers, photos and mementos in waterproof bags to be taken with
  your emergency kit. Large/heavy valuables could be protected in a strong cupboard.
• Remain indoors (with your pets). Stay tuned to your local radio/TV for further information.

On warning of local evacuation (Near landfall area, around Machilipatnam)

Based on predicted wind speeds and storm surge heights, evacuation may be necessary.
Official advice will be given on local radio/TV regarding safe routes and when to move.

• Wear strong shoes (not thongs) and tough clothing for protection.
• Lock doors; turn off power, gas, and water; take your evacuation and emergency kits.
• If evacuating inland (out of town), take pets and leave early to avoid heavy traffic, flooding and wind hazards.
• If evacuating to a public shelter or higher location, follow police and State/Territory Emergency Services directions.
• If going to a public shelter, take bedding needs and books or games for children.
• Leave pets protected and with food and water.

When the cyclone strikes 

• Disconnect all electrical appliances. Listen to your battery radio for updates.
• Stay inside and shelter {well clear of windows) in the strongest part of the building,
  i.e. cellar, internal hallway or bathroom. Keep evacuation and emergency kits with you.
• If the building starts to break up, protect yourself with mattresses, rugs or blankets under a
  strong table or bench or hold onto a solid fixture, e.g. a water pipe.
• Beware the calm 'eye'. If the wind drops, don't assume the cyclone is over; violent winds
  will soon resume from another direction. Wait for the official 'all clear'.
• If driving, stop (handbrake on and in gear) - but well away from the sea and clear of trees,
  power lines and streams. Stay in the vehicle.

After the cyclone

• Don't go outside until officially advised it is safe.
• Check for gas leaks. Don't use electric appliances if wet.
• Listen to local radio for official warnings and advice.
• If you have to evacuate, or did so earlier, don't return until advised. Use a recommended route and don't rush.
• Beware of damaged power lines, bridges, buildings, trees, and don't enter floodwaters.
• Heed all warnings and don't go sightseeing. Check/help neighbours instead.
• Don't make unnecessary telephone calls.

Note: Managers of resorts, hotels, motels, and caravan parks should take steps to ensure visitors are aware of the dangers and know what to do in the event of a cyclone. Free Protecting Caravans information is available from your State/Territory Emergency Service.

CATEGORY 1 CYCLONE LEHAR WRAPPING IN DRY AIR?

METD WEATHER
Akshay Deoras
Severe Weather Forecaster,

Today afternoon, Tropical Storm LEHAR intensified to a Category 1 Cyclone as its max sustained winds reached 65 Kt and as of this post continue to be at 65Kt as the cyclone tracked west-northwest at around 07Kt (13km/hr) in the Bay of Bengal about 965km SE of Vizag,1100km east-south east of Machilipatnam,1050km east - south east of Kakinada,Andhra Pradesh and having tracked 200km from Port Blair after bringing heavy rains and winds in the Andaman and Nicobar Islands. However I am personally not convinced with the latest image of the system and some more observations, lets have a look here

Dry Air-

Like mentioned in yesterday's blog post, the amount of dry air entering the Bay of Bengal from East/North East India is increasing every hour as Cyclone LEHAR continues to act like a magnet doing this job. A 24hr comparison of the CIMSS Total Precipitable Water (TPW)clearly shows an increase in the spread of dry air which even now seems to be wrapping around the system in its northern periphery.

The topmost image shows TPW as of yesterday and the below image shows the latest precipitable water. One can see that blue,green region has moved further down (southward) as the Cyclone LEHAR presently at 12.5N,91.0E continues to move NW. Possibly the dry air is interacting with the outer rainbands- Northern and North-Western rainbands of LEHAR as can be possibly inferred from this latest IR-NHC imagery via CIMSS

The 1330UTC obtained NHC enhancement image shows a more or less oval structure of the CDO (Central Dense Overcast) feature which continues to obscure the LLCC. An animation of the IR imagery shows the centre is losing the convergence. It also indicated a possible exposed LLCC (although for a short time) and that the convection is possibly re-organising around a new centre marked by a very favoured wind field as can be seen in this image

The above IR BD image has contours of lower air convergence imposed on it. An increasingly favourable 30Kt region is developing coupled by an excellent poleward flow of 40Kt peak.
SST continues to be very favourable, in the 29C range which is overpowering the moderate 20kt wind shear in the region.

An analysis of all indicates that dry air has likely collided with the outer northern rainbands of Cyclone LEHAR and the convection is re-organising around a new centre and the system is overall maintaining its intensity. Over the next 12hrs, Cyclone LEHAR shall intensify gradually although I don't expect a Rapid Intensification yet considering the fact that wind shear are forecasted to remain moderate all the time in LEHAR's journey. Dry air wrapping shall be a factor to watch out and hence still I don't expect it to intensify beyond Category 2 which shall happen later tomorrow,26th Nov.

Given the fact that dry air interaction will act as a barrier and the SST will be decreasing beyond  36hrs from now ( morning of 27th Nov 2013), LEHAR shall make a landfall as a Category 2 cyclone close to Kakinada,Andhra Pradesh on the morning of Thursday,28th Nov 2013. The state of sea in the Bay of Bengal shall remain ROUGH in this period and hence fishermen shouldn't venture out in the sea till Friday,29th Nov 2013.


More details are awaited like potential damage to Andhra Pradesh coast which will enable to put the graphic map so STAY TUNED!!!

Tropical Storm "Lehar" threatens India!

METD WEATHER
Akshay Deoras
Severe Weather Forecaster

With just over a month from the landfall of disastrous Category 5 cyclone Phailin  and just a few days after Tropical Storm Helen , the Bay of Bengal is all set to host another Tropical Cyclone which will be soon officially called as "Cyclone Lehar".. At METD WEATHER, Saffir Simpson Scale is followed and hence we have already named the area of deeply organised convection about 1560km SE of Vizag,Andhra Pradesh as Tropical Storm Lehar given the estimated maximum sustained winds of 35kt as of today morning. This Tropical Storm which at present lies in the periphery of land, The Andaman and Nicobar Islands is all set to pass dangerously between Little Andaman Island and Port Blair between late tonight, 24th Nov and morning of tomorrow,25th Nov 2013 as a "Tropical Storm category" with max winds reaching upto 100Km/hr accompanied by strong rains and storm surge likely upto 10ft.... Lets have a look at the dynamics of Tropical Storm Lehar in the Bay of Bengal-

Shown above is a composite view of Tropical Storm Lehar. The topmost simple Infrared view (top left) and IR-BD view (Top Right) clearly shows almost circular convection centre with cloud tops reaching upto -70C which is an indicator of organising convection and intensification of the system. Interesting thing to note in the lower images is the organising of outer bands- rain bands- banding feature around the LLCC (Low level circular centre) as can be inferred in the NRL images. The lack of symmetry is being attributed to the periphery of the land which isn't allowing the system to undergo rapid intensification stage as it churns in the sea having temperature of 29C...

A look at the wind profiles & dynamics show that Tropical Storm Lehar is being troubled by moderate wind shear of 30kt to the north and south of the centre and 20kt to its East disabling it to intensify robustly. Over the past 12hrs, convergence at the lower atmospheric profile has decreased slightly along with the poleward outflow which now stands to be 40kt peak as against 60kt peak 12hrs ago...

As the system steers North West slowly ( at present with a velocity of 17km/hr), after the encounter with Andaman and Nicobar Islands, the system shall get a clearance from land to intensify.

Shown above is the Sea Surface Temperature view via CIMSS.. Here Red colour represents Sea Surface Temperature of 30C, Orange shows 29C, yellow shows 27-28C. Thus the sea coupled with the moisture content will be favourable for intensification. But the question arises, will Tropical Storm Lehar reach a Category 5 status like Tropical Cyclone Phailin ??

The answer at the moment seems- NO

Here is the reason,

This is CIMSS view of the wind shear in knots across Bay of Bengal.. Here solid white lines indicate an increasing shear tendency: unfavourable for storm intensification. Over the Bay of Bengal, it seems the wind shears will remain considerably higher than they were during Phailin's time as a result this factor will always try to reduce the intensity but with other factors favourable, Tropical Storm Lehar shall intensify to atleast Category 2 although JTWC says it can go upto Category 3. As the sea few hundred kilometers offshore Odisha and Andhra Pradesh is slightly cooler, intensification may not be that high and hence for now, people shouldn't panic or compare this cyclone with Phailin or Supercyclone of 1999 or with the US hurricane like Katrina.

Where will it head ?

This is always a million dollar question. At the moment, the sub tropical ridge seems to be steering the system towards Indian coast but the area in North Bay of Bengal is being monitored for the development of high pressure at the lower levels (850mb or say 5000 ft AGL). If the high pressure forms in that region, the cyclone shall not move much North in its NW journey and in that case its region of landfall shall be south of Vizag in Andhra Pradesh on the morning of 28th Nov 2013, Thursday.. 

However as GFS 00z is showing, if the high pressure doesn't form, system under the influence of sub-tropical jet stream of India will curve a bit north and make a landfall near Brahmapur,Odisha- apparently at the same place like Cyclone Phailin on the morning of 28th Nov 2013, Thursday

Where ever it shall head, people living along the coastal line from Kakinada,AP till Brahmapur,Odisha shall pay attention towards the development of this system which will be covered on METD WEATHER's facebook page (www.facebook.com/deorasakshay) and on this blog also

Once the forecast becomes more clear, an alert map will be issued by METD WEATHER

*** Preparation*** 

Rough Sea of Bay of Bengal will start now onwards and will continue till Thursday,28th Nov. Fisherman are requested not to venture with their ships/boats.. 

VIA BOM,Australia (People of Andhra Pradesh-Odisha Coast must note) 

When a cyclone watch is issued

• Re-check your property for any loose material and tie down (or fill with water) all large, relatively light items such as boats and rubbish bins.
• Fill vehicles' fuel tanks. Check your emergency kit and fill water containers.
• Ensure household members know which is the strongest part of the house and what to do in the event of a cyclone warning or an evacuation.
• Tune to your local radio/TV for further information and warnings.
• Check that neighbours are aware of the situation and are preparing.

CATEGORY 5 CYCLONE PHAILIN TO IMPACT ODISHA TODAY,EXTENSIVE DAMAGE EXPECTED

METD WEATHER
Akshay Deoras
Severe Weather Forecaster

*** CATEGORY 5 CYCLONE PHAILIN HEADING TOWARDS ODISHA, BIG DAMAGE EXPECTED FROM TODAY*** 

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).

CYCLONE PHAILIN NOW IS STRONGER THAN THE 1999 SUPERCYCLONE OF ODISHA

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) 

POTENTIAL IMPACTS TODAY

* 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. 

SAFETY MEASURES (Via Ready.gov)

• 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.

TROPICAL CYCLONE WARNING FOR EAST INDIA- ODISHA UNDER THE THREAT

METD WEATHER
AKSHAY DEORAS
SEVERE WEATHER FORECASTER

JOIN METD WEATHER FACEBOOK FOR LATEST DETAILS- facebook.com/deorasakshay

The second part of 2013 North Indian Ocean Cyclone Season has started with a bang with a new Tropical Storm (we call it 02B as per JTWC) already born in the Bay of Bengal. This new Tropical Storm 02B in North Andaman Sea near 13N,93.5E approximately 1200km east-south east of Visakhapatnam already has wind of 35KT (and hence already lies in the Tropical Storm Category of the Saffir Simpson Scale) 

Seen above is the latest IR-NHC imagery of the Tropical Storm 02B via CIMSS showing the system as Invest (I). Distinct banding features are visible west of the low pressure as the LLCC (Low Level Circulation Centre) is trying to organise in the warm Bay of Bengal having SST of ~29C. LLCC is also becoming more exposed and consolidating also. At the surface level too, the system continues to enjoy lower southern convergence of ~30kt and the convection continues to boost up given the excellent upper air divergence to the south of the system as the system is tracking along the southern periphery of the Subtropical Ridge although its experiencing moderately sheared environment to its south-west.

Already heavy rains have been reported in Andaman and Nicobar Is. Entire Andaman and Nicobar Is will continue to get heavy rains today with high velocity winds as the Tropical Storm intensifies close to the area. After the Tropical Storm moves NW tomorrow (10th Oct) onwards, there will be a decline in the rainfall in this area. 

The Tropical Storm 02B shall be curving to NW as it steers in a moisture rich,higher sea temperature of Bay of Bengal considering the available TPW (Total Precipitable Water). Atmospheric conditions also are expected to be conducive for this Tropical Storm to intensify to Category 1 (say with peak winds of around 80KT) around tomorrow,10th Oct afternoon or so and amidst produce "Rough Sea" in the Bay of Bengal in the highlighted region of METD WEATHER alert. Models are converging for landfall of this system along the Odisha coast on Saturday,12th Oct 2013 (Although landfall like conditions shall start from afternoon-evening of Friday,11th Oct 2013). 

The approximate landfall of this system seems to be around Brahmapur in Odisha however landfall like conditions (which includes heavy rains, gusty winds prominently) will be widely experienced along the entire Odisha coast even stretching upto North East coast of Andhra Pradesh which is bordering Odisha around Friday-Saturday. 

In the forecast map, METD WEATHER has issued a Tropical Cyclone Warning for East India Coast that prominently includes Odisha and Andhra Pradesh and heavy rainfall extension in Jharkhand also (May stretch upto Bihar on 13/14th Oct 2013). 

IMPACTS- 

*Damage to boats,ships in the "Rough Sea" or in the ports of Odisha (Rough Sea starts now and shall continue till 14th Oct 2013. Fisherman are also advised now to enter the Bay of Bengal till 13/14th Oct 2013. 

* Considering the fact that as of now the Tropical Storm will intensify to Category 1, widespread damage is likely along Odisha coast initially and later on moving into interior (particularly near the landfall area). Damage shall start from afternoon/evening of Friday,11th Oct 2013.

* Extensive damage to huts,trees and weak settlements is likely during the landfall and there exists a high flood threat for Odisha coast and interior as the weakened system (Tropical Depression will bring heavy rains).

* Disruptions of rail,air,road traffic is possible around the capital Bhubaneshwar. 

PRECAUTIONS (Via BOM: Bureau of Meteorology, Australia) 

When a cyclone watch is issued (Extended for North East AP and areas in orange colour in the alert map) 

• Re-check your property for any loose material and tie down (or fill with water) all large, relatively light items such as boats and rubbish bins.
• Fill vehicles' fuel tanks. Check your emergency kit and fill water containers.
• Ensure household members know which is the strongest part of the house and what to do in the event of a cyclone warning or an evacuation.
• Tune to your local radio/TV for further information and warnings.
• Check that neighbours are aware of the situation and are preparing.

When a cyclone warning is issued (Odisha coast) 

Depending on official advice provided by your local authorities as the event evolves; the following actions may be warranted.

• If requested by local authorities, collect children from school or childcare centre and go home.
• Park vehicles under solid shelter (hand brake on and in gear).
• Put wooden or plastic outdoor furniture in your pool or inside with other loose items.
• Close shutters or board-up or heavily tape all windows. Draw curtains and lock doors.
• Pack an evacuation kit of warm clothes, essential medications, baby formula, nappies,
  valuables, important papers, photos and mementos in waterproof bags to be taken with
  your emergency kit. Large/heavy valuables could be protected in a strong cupboard.
• Remain indoors (with your pets). Stay tuned to your local radio/TV for further information.
• DON'T TRAVEL TO COASTAL AREAS TO SEE THE TROPICAL CYCLONE

Arabian Sea system shows "signs" of life after models kill it! BOB Depression/TS to impact Tamil Nadu

METD WEATHER
Akshay Deoras
Severe Weather Forecaster

Bay of Bengal Update- 

As was expected, the BOB system ( hence to be called as Tropical Depression) is churning in the Southern Bay of Bengal.

The above morning IR-BD imagery shows the exposed LLCC centred somewhere in the 9.5N,83.5E which is ~ 530km SE of Chennai.
So far the max sustained winds are around 55km/hr with MSLP ~ 1002mb.

The system has intensified since the last post due to favoured conditions. The model analysis suggests that the system is moving in a region of 30kt upper air divergence and around 15kt low level convergence with the V wind shear to be around 10kt.

Based on the models and observations, it appears that the system which at present is a Tropical Depression will INTENSIFY to a marginal Tropical Storm status ( With max sustained winds of around 65kt )

As a Tropical Storm, it shall head for a landfall in a region

 Between Ammapatam to Cuddalore ( Tamil Nadu) 

    ON Tuesday,Oct 30 2012 night period to Oct 31 2012 Wednesday early   morning hours- 

(10PM IST- 0400hrs IST) 

IMPACTS- 

* ROUGH SEA WILL CONTINUE NEAR THE TAMIL NADU COAST TILL 1ST NOV 2012 

* STRONG GUSTY WINDS WILL BE WITNESSED in ENTIRE TAMIL NADU, PONDICHERRY ( PUDUCHERRY),COASTAL BORDERING ANDHRA PRADESH BEGINNING TONIGHT AND ENDING AFTER THE SYSTEM PASSES

* HEAVY RAINS  ARE LIKELY IN THE AREAS IN CYCLONE's PATH AND ADJOINING AREAS AS SHOWN IN THE MAP AND THEN STRETCHING AS NORTH AS HYDERABAD on 31st Oct 2012 AS THE SYSTEM MOVES. MODERATE RAINS IN KARNATAKA AS WELL. 

* CHENNAI ALSO WILL WITNESS HEAVY RAINS,WINDS IN THE PERIOD 

* Flooding Potential across INTERIOR TAMIL NADU 

After the landfall, the depression will move inland and will be steered by the upper air winds which will move the system North-North East wards on Oct 31 due to which the rainfall shall spread into Karnataka,Andhra Pradesh,Maharashtra and the entire Eastern coastal states on 1-2nd Nov 2012. 

The rainfall then shall spread further reaching Northern Maharashtra-Central MP latitude by Nov 2-3 2012 due to which Nagpur will get rainfall in a period between 1-4th Nov 2012 with cloud skies. ( For exact details refer METD WEATHER FACEBOOK PAGE) with highest chances of rains on Nov 2-3. 

II- Arabian System- 

The recent GFS models have turned a lot since the last post and now they aren't showing any chance of Arabian System to form or it merging with the Bay Storm/Depression. 

Infact as was reported on METD WEATHER Facebook, the system faced a lot of problems on Oct 28th i.e yesterday as there was no proper low level convergence to grip the convection. 

However things changed today and lets have a look-

Animation- 

http://rammb.cira.colostate.edu/products/tc_realtime/loop.asp?product=4kmirimg&storm_identifier=IO962012&starting_image=2012IO96_4KMIRIMG_201210282200.GIF

Above- 

The top most image is of 28th Oct 0730GMT where the system faced a lot of problems due to lack of LL convergence. The below image is of Oct 29 0730GMT showing that the system has organised a lot since last 24hr given the developing Low level convergence of around 10kt. 

The system continues to remain in an excellent poleward outflow ( associated with the Bay system) of around 30kt and favoured SST to support robust convection. The wind shears are also relaxed (vertical). 

Here is a look at the latest precipitation embedded in the system- 

One can observe that outer rain bands have formed and there seems to be a developing LLCC with more banding from the Southern periphery of the system

Thus, I do expect that the Arabian Sea system will intensify further given the excellent conditions available. However, there is a decreasing confidence at the moment whether the system will head towards Gujarat or not. 

Considering the model runs and vicinity of the Bay system, it appears that the Arabian Sea system shall head NE gradually and move inland somewhere in Karnataka when the Bay system will be present. So in such a case, the chance of Arabian System forming into a Tropical Cyclone is very very less. However it can get converted into a Tropical Depression, move NE and move inwards in the Western Coast of India

As a result, the warnings issued previously for Gujarat STAND CANCELLED

TROPICAL CYCLONE/DEPRESSION ALERTS FOR INDIA

METD WEATHER
Akshay Deoras
Severe Weather Forecaster

"THE TROPICAL CYCLONE/DEPRESSION ACTIVITY BOTH IN THE ARBIAN SEA AND BAY OF BENGAL IS EXPECTED. STORM TRACKS CAN THREATEN INDIA"

"" FOR THE LATEST UPDATES, FOLLOW METD WEATHER ON FACEBOOK"""

The flattened 2012 North Indian Ocean Cyclone Season has revived with two candidates. BOB 01 and Tropical Storm Murjan. As METD WEATHER doesn't consider it, lets not discuss those past systems.

I- Bay of Bengal ( BOB)

The above DUNDEE imagery ( IR) spectrum shows massive CB clouds in the Central BOB with cloud tops around -30C at the moment. The imagery is of 0530PM IST. 

Animation (IR) here shows how the system has evolved robustly. 

http://rammb.cira.colostate.edu/products/tc_realtime/loop.asp?product=4kmirimg&storm_identifier=WP932012&starting_image=2012WP93_4KMIRIMG_201210270900.GIF

The above imagery shows that the system has organised much as seen from its symmetrical geometry. The system is encountering a building ~10kt convergence at the lower levels with extremely favorable thermodynamic conditions. The system continues to have 20kt upper air divergence with relaxed wind shears (vertical of 05-10kt barely) to support cyclogenesis in the 28-30C SST in the region.

Considering the favoured conditions, it appears that the system is very likely to strengthen further in the next 48hrs before it approaches the Indian SE and Sri-Lanka coast. 

The system can advance further and get a "Tropical Storm" status in the next 48hrs...

Where will it head? 

As per the 12z model which has been consistent, the system will be heading West and will make a landfall in a region between Cuddalore,Tamil Nadu and Northern Sri Lanka region. The area is purposively being kept large to settle the landfall uncertainties.  

The landfall seems to be happening on Oct 30 2012 in the morning - afternoon time ***
*** time may change***

Potential Impacts-

* Rough Seas offshore Tamil Nadu will initiate within 48hrs and will increase as the system approaches. 

* Heavy Rains with strong winds shall initiate in the Eastern Tamil Nadu region from 29th Oct and increasing ( VERY HEAVY) during the landfall. 

-------------------------------

II- ARABIAN SEA

The above DUNDEE imagery showing a wedge region of convection in the Southern Arabian Sea. So far the region hasn't shown any significant convergence and hence the system continues to remain widespread in the Arabian Sea. 

However, as the Bay System ( Possibly will be named Tropical Storm Nilam) will interact with the Arabian System and due to this, the moisture amounts of the Arabian System will increase. 

As the Arabian System moves as per the estimated NW track due to the upper air wind pattern, it seems that system will intensify robustly ( Its having around 15kt lower convergence, 10kt upper air divergence, around 5-10kt vertical wind shear, favoured SST), 

This system has a very high chance of getting converted to a Tropical Storm and due to its path, Western India will face some rainfall events. 

At present, at the upper level a shortwave trough is digging through India and as the trough exits which eventually co-incides with the system's northerly approach, the system will be steered by the jet streams which will start the system turning NE towards India-Sindh region

Model uncertainty exists at the moment however considering the consistency and the upper air pattern, it appears that the system will make a landfall somewhere near NW Gujarat-Sindh border 

on Saturday,Nov 3 2012 *** 

*** timings will vary*** 

The region of landfall is purposively kept wide to avoid uncertainties of the models 

The probable landfall areas ( will be modified suitably)

Entire West Coastal Gujarat,Sindh coast. 

IMPACTS-

Rainfall shall happen across Western Coast of India ( excluding Kerala) with more amounts towards Goa,Western Maharashtra,NW Maharashtra, Central Maharashtra and vicinity. 

LAKSHADWEEP ALSO WILL GET  RAINS AS THE SYSTEM WILL APPROACH VERY CLOSE TO IT

Mumbai,Pune etc will get rains around 3-4th Nov period *** 

The landfall impacts shall vary with the storm's intensity hence it shall be notified later on. 

Rough seas shall persists near the Indian coasts

STAY TUNED FOR UPDATES

Tropical Cyclone/Depression Watch CANCELLED for East,South-East Coast of India

METD WEATHER
Akshay Deoras
Severe Weather Forecaster



*** TROPICAL CYCLONE/DEPRESSION WATCH CANCELLED***
*** AS OF 06Z,21ST APRIL 2012 CONDITIONS NO LONGER EXSIST FOR THE FORMATION OF A SIGNIFICANT TROPICAL CYCLONE