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 Storm Keila forms in the Arabian Sea

METD WEATHER

AKSHAY DEORAS

SEVERE WEATHER FORECASTER

"" TROPICAL CYCLONE FORMATION ALERT""

FOR INSTANT UPDATES AND DISCUSSIONS-

JOIN US ON FACEBOOK HERE

The much Anticipated and Puzzling Cyclone " Keila" has finally formed with the Joint Typhoon Warning Center ( JTWC) officially confirming its formation.

In an update provided by the JTWC, as of 2230hrs( 8th June) JTWC has mentioned Tropical Cyclone Formation Alert

at 18.7N,69.8E 180NM West of Mumbai

METD WEATHER HAD ISSUED A HIGH RISK YESTERDAY ONLY FOR FORMATION OF CYCLONE IN NEXT 24HRS!

FORECAST-

THE AREA OF CONVECTION CENTERED AT 18.7N,69.8E AS MENTIONED IN PREVIOUS FEW ALERTS HAS ORGANIZED. VISIBLE ANIMATED SATELLITE IMAGERY SHOWS ROBUST CONVECTION HAPPENING WITHIN THE SYSTEM SITUATED IN A POOL OF SEA SURFACE TEMPERATURE OVER 30C

THE IR-BD IMAGERY SHOWS A NICE OUTFLOW OF THE SYSTEM IN THE WESTERN PERIPHERY OF THE LOW LEVEL CYCLONIC CIRCULATION.

RAINBANDS ALSO HAVE ORGANIZED IN LAST 12HRS GIVING A MORE SYMMETRIC SHAPE TO THE TROPICAL STORM IN AN ENVIRONMENT OF FAVORABLE LOW LEVEL CONVERGENCE OVER 40KT!

WITH SUFFICIENT DIFFLUENCE AS THE UPPER DIVERGENT WINDS ARE OVER 40KT, THE SYSTEM HAS TREMENDOUS POTENTIALS FOR INTENSIFYING IN THE NEXT 24HRS.THE WIND SHEARS ARE ALSO FORECASTED TO BE WEAK FOR NEXT 24HRS!

WITH A PRESSURE OF AROUND 998MB, KEILA REMAINS A TROPICAL STORM WITH PEAK WINDS OF 61KM/HR ( APX)

WHERE WILL IT GO?

CHECK THE ALERT MAP FOR DETAILS