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

2012 WINTER FORECAST OF INDIA

(C) 2012 AKSHAY DEORAS

metdweather.blogspot.com

All Rights Reserved.....

2012 Winter Forecast of India

METD WEATHER
Akshay Deoras
Severe Weather Forecaster

14th Oct 2012
0400hrs IST
Nagpur,India

Dear Readers,
The Official forecast for the 2012 Winter in India is below.

This year's forecast is an experimental forecast as we have used a new technique for weather forecasting. Till the last year, the winter forecast used to be made using the weather models directly. However there are many errors in it which ultimately spoil the forecast accuracy. This year's winter forecast consists of two parts. One is a technical part having all the scientific background for the forecast whereas the other one is the non technical or the public version for lucid understanding of the people.

As per the forecast, it appears that Northern half of the country will experience cooler than normal winter whereas southern half will experience warmer than normal conditions. As a result, the net forecast for 2012 Winter in India seems "NORMAL WINTER''

We also expect to cross the 2,00,000 pageviews after the Winter forecasts are published.

Thanks for the support !

For any feedback/suggestion, you can mail me at metdweather@live.com

Greetings!

Akshay Deoras

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List of topics-

1) Forecasting Basic
2) Current ENSO status,expected ENSO behaviour during 2012 Winter
3) Introduction to the Arctic Oscillation
4) **Relation between the Arctic Oscillation and Minimum temperatures during winter
5) Estimated Arctic Oscillation Index during 2012 Winter
6) The 2012 Winter Forecast
7) References & Acknowledgements

** We are introducing this relation for the first time 

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FORECASTING BASIC-

The South West Monsoon retreat is almost complete as the Sun is apparently shifting Southwards which plays a major role in the decrease in the average surface air temperature over Central and Northern India prominently. 

The Winter Forecast for India isn't restricted to the local weather phenomena which people believe i.e if there has been strong monsoon there will be good winter and vice versa. It has now been realized that the entire weather of India and many parts of the world is governed by the Global Weather Phenomena of El Nino Southern Oscillation happening in the Equatorial Central Pacific Ocean briefly. 

Though not fully understood, the phenomena is of oscillating sea surface temperatures in equatorial pacific regions between above normal,normal and below normal temperatures. The scientific reason is with the variation in the trade winds blowing eastward at the surface level which leads to changes in sea water level in some areas of Pacific Ocean like Indonesian coast, Australian Coast and offshore Peru.

The phases of ENSO are 

El Nino- When Sea Surface Temperature(SST) of Eq Pacific is warmer than normal

Neutral- When SST is normal

La Nina- When SST is cooler than normal in Eq.Pacific 

It has been widely observed that winters in India go comparatively cooler than normal during La Nina and warmer than normal during an El Nino. The reasons are still not known and aren't fully accepted by weather forecasters like me. 

In the 2010 Winter Forecast by METD WEATHER, we had postulated the  *** Jet Stream velocity vector variation with the ENSO as a parameter for forecasting the 2010 Winter Forecast as stated below.
The entire forecast can be seen here-

http://metdweather.blogspot.in/2010/11/2010-winter-forecast-for-india.html

"" La Nina also strengthens the Jet streams.

 Blocking high pressure over Tibet

As cooler temperature builds in Tibet, a high pressure area builds over Northern India and also in Tibet, Right now the air pressure is as high as 1040mb. The Jet streams flowing from west to east are blocked by this air pressure so the jet stream splits into two branches or mostly jet stream digs South instead of North

As the high pressure blocks the jet stream, jet stream digs southwards in India covering areas of Punjab,Haryana,Delhi,Madhya Pradesh,Maharashtra and much of the North-Central India.

The Jet rarely flows over Jammu and Kashmir ( except for Western Disturbance).

So more cool air digs southwards than normal during La Nina.

The intensity of the high pressure over Tibet and North India is related to the La Nina phenomena""


*** Jet Streams here refer to the Subtropical Jet Streams

In 2011, We continued with the La Nina- Jet Streams relation for forecasting the season. The forecast can be seen here

http://metdweather.blogspot.in/2011/10/2011-winter-forecast-of-india.html

"""Explanation to Cooling effect of La Nina

 A possible explanation which I think is the application of concept of intensified jet streams during la nina over Indian continent. 

La Nina is marked by the increased convection in west pacific than east pacific due to strong winds towards west and vice versa at the upper air. 

Thus an amplified subtropical jet stream will tend to bring more cold air in the Indian subcontinent particularly in Northern,Central and . In the case of El Nino, due to less amplified subtropical jet streams the blast of cool air is partial and it brings a noted warmer effect on the surface air temperatures. 

Example- A river is like ***Jet Stream. When the river's speed is greater it will drag the stones in its way. When speed is less, stones will not be carried with it. Stones can be compared with cold air.  """

*** Jet Streams here refer to the Subtropical Jet Streams

However it was later realised that the reasoning isn't sufficient to co-relate ENSO with Indian Winter and the forecasts showed strong anomaly when were compared with the actual conditions of 2010,2011. So we shall not consider this parameter in complete sense in this forecast.

In an attempt to establish the relationship between the Indian Winter with certain atmospheric oscillations, we came across the Arctic Oscillation (AO). We shall see the details regarding the AO-Winter interaction below

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2) Current ENSO status and expected ENSO behaviour in 2012 Winter

After a strong El Nino pattern which ended during early 2010, neutral conditions were observed for a few months after which La Nina pattern got established which continued through the 2010 winter and ended during summer of 2011. However a weak La Nina developed again and continued through the 2011 winter.

ENSO Neutral condition has been observed since then continuing even today.

Since  July end-August, probability of an El Nino emerging before the Northern Hemisphere winter was being considered as very high and the SST in the Equatorial Pacific Ocean tended towards a positive ( El Nino) phase.

Above- SST Anomaly as analysed on Aug 26 2012 shows a pool of warmer than normal SST ( in the red encircled region) in the vicinity of the Nino 3.4 region.

The July August September ( JAS) SST anomaly in the Nino 3.4 region was +0.3C

3-Month period      ONI  (C)
        MJJ                 0.0
        JJA                 0.1
        JAS                0.3      

But from September mid onwards, SST anomalies started decreasing ( approaching zero) in all the NINO regions including Nino 3.4.

The SST Anomaly analysed on 7th Oct 2012 is given below

  

One can observe that SST in the encircled region has cooled down as compared to the August 2012 situation.


The latest weekly SST departures are:
Niño 4      0.3ºC
Niño 3.4   0.1ºC
Niño 3     -0.1ºC
Niño 1+2  -0.1ºC

Thus one can infer that SST in the Central Pacific Ocean is turning towards a neutral and not towards the positive anomaly mode from September end. 

The 850mb winds in the Pacific Ocean which are a measure of the intensity of the Easterly Trade Winds are consistently showing anomalies ( westerly anomalies) across North Indonesia area. Easterly trade winds otherwise seem to be showing no anomaly and thus reducing the chance of an El Nino forming for a few more months.

The CPC considers a three month group SSTA in the ONI plots. So it can be expected that the ONI for August- Sept-Oct settles to around +0.40C

Above is the IRI Probabilistic ENSO Forecast. The forecast still calls for a 50% + chance for El Nino formation till DJF 2012-2013 period.

So according to our estimates, The ONI will be in the Neutral Range in the ASO period and shall hit the El Nino threshold of +0.5C in the SON period i.e El Nino Conditions may emerge around November end to December 2012 with a very weak amplitude.

So for those forecasters forecasting using the ENSO, it appears that more or less a ENSO Neutral will persists through the Northern Hemisphere winter with a slight El Nino conditions emerging in the year end.

The tendency of ENSO will depend on whether El Nino gets established this year end or not.
However, in this forecast we are least bothered about the ENSO
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3) Introduction to the Arctic Oscillation - 

AO- Arctic Oscillation is not much known to the people of India as the parameter is not used for making any forecast ( Long Range/Short Range) relating to India. However, in this study we observed that the AO seems to have some association with the Indian Winters. Before we get into the observational part, lets understand the basics of the AO

AO is an oscillatory phenomena characterised by dipolar natured air pressure across the High Latitudes and the Mid Latitudes simultaneously. AO is  Characterised by two prominent modes-
1) The Positive
2) The Negative

The Positive Mode of the AO is characterised by the formation of low pressure in the Polar Regions and subsequent higher pressure in the Mid latitudes refraining the cool air from the higher latitudes to spread in the mid latitudes. Vice versa conditions are observed during the Negative Mode

(all jet streams mentioned below are the subtropical jet streams)

The most important feature of the AO is that it influences the subtropical jet stream. In the case of the positive AO, the jet streams have a zonal flow from the usual west-east direction. Whereas in the case of the Negative AO, the jet streams don't have a zonal flow rather they have a wave shaped ( comprised of crest and troughs) as seen in the below figure-

In the above figure, one can clearly see how the cold air enters the mid latitudes during the Negative phase.

Arctic Oscillation is given by the Arctic Oscillation Index ( AOI). The AOI is one of the most unpredictable index and one can't predict how the AO will behave as it varies stochastically.

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4) Relation between the Arctic Oscillation and minimum temperatures during winter

Since the volume of investigated data is large, we use the SAMPLING method from statistics.

Hypothesis- 
1) It has been observed from the data that the minimum temperatures in a region stretching southwards from the Maharashtra-Madhya Pradesh have a inverse relation with the AOI
i.e the higher the AOI (MORE POSITIVE), the lower the temperatures during the Winter ( as compared to the previous years).

2) Minimum temperatures in a region stretching northwards from the Maharashtra-Madhya Pradesh border are directly proportional to the AOI 
i.e the lower the AOI ( MORE NEGATIVE IN MAGNITUDE) min temperature VS previous year's temperature. 

3) The geographical boundary at the Maharashtra-Madhya Pradesh region across which the AOI varies directly/inversely is being coined as the Deoras limit. 

 The result prominently applies for the December month so we shall investigate the relation for December month only

*** South of Deoras Limit*** 

Data set for Nagpur,Maharashtra

Average Monthly min temperature (1950-2002)
http://indiawaterportal.org/met_data/

AOI Historical ( 1950-2012)
http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/monthly.ao.index.b50.current.ascii.table


  YEAR        MONTH         AOI           AVG MIN TEMP(C)
   1950            DEC             -1.928           13.028
   1951            DEC              1.987           12.765


   1951            DEC              1.987           12.765
   1952              "                  -1.827          14.991

   1969              "                  -1.856          13.232
   1970              "                   -0.399         11.944

   1994              "                   0.894          13.044
   1995              "                   -2.127         15.403

   1995              "                   -2.127         15.403
   1996              "                   -1.721         13.101


One infers that for a period say 1951 the min avg temp for december was lesser than 1950 when the AOI had opposite relation
Thus through sampling, the probability of the above relation holding good is high though there are some cases where the relation doesn't hold good.

*** NORTH OF DEORAS LIMIT***

For simplicity and to reduce the length of this forecast, we shall consider the case for Ludhiana,Punjab. However from the given links, one can verify that the relation holds good for all the areas North of Deoras Limit

    YEAR        MONTH         AOI           AVG MIN TEMP(C)

     1950            DEC             -1.928              5.457
     1951            DEC              1.987              8.439


     1951            DEC              1.987              8.439
     1952              "                  -1.827             7.523

     1997              "                   -0.071             5.676
     1998              "                   1.353              8.113

     1972              "                    1.238             8.349
     1973              "                    -0.181            5.475


Thus through sampling, the probability of the above relation holding good is high though there are some cases where the relation doesn't hold good.

Though it has not been calculated but we do suspect that when calculated on a 3-4 month basis, the results will come better and the anomalies in the result will decrease considerably. 

Reason- 

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5) Estimated Arctic Oscillation Index during 2012 Winter

As stated above, the AO is a stochastically varying phenomena. September 2012 had AOI of 0.772

Here is the observed and forecasted value of the AOI

Thus from the models, it can be inferred that AOI will remain in the negative mode for remaining half of Oct for sure 

Since its an experimental forecast, I think that the AOI will remain in the negative mode till somewhere Mid November after which it will oscillate between the negative and positive phase.

So the OND average AOI as per my estimate shall be negative considering the happening Oct negative AOI and estimated Nov AOI
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6) The 2012 Winter Forecast

Like said above, it will all depend on the AOI. If the net AOI turns out to be positive then areas South of Deoras Limit will experience slightly cooler than normal winter and vice versa

However considering the expected negative AOI, it appears that Northern Deoras Limit regions will experience a marginal cooler than normal winter whereas areas south of the limit shall experience a slightly warmer winter with the intensity increasing towards South India 

Zone Wise- 

North India- 

1] Jammu and Kashmir,Himachal Pradesh,Uttaranchal

  Normal winter conditions will be observed here.The temperature anomaly ( All season Average) shall be around 0.2C to 0.1c less than average temperature.

2] Punjab,Haryana,Chandigarh,New Delhi

The overall temperature anomaly in these regions depends on the western disturbance. However it does appear that these regions will witness ( 0.5C to 0.7C) less than average temperature. 

After the snowfall events, temperature in the plains will drop suddenly but average will be near to the predicted value.

** We shall not estimate the number of western disturbances as its a debatable topic. However, the precipitation in the hilly areas seems NORMAL

3] Madhya Pradesh,Rajasthan,Uttar Pradesh,Gujarat 

A Cooling effect is likely in these areas as the jet streams coupled with the negative AOI influence shall lead to drop of temperatures due to more cool air incursion. 

** Uttar Pradesh will have NORMAL winter and hence I don't expect any anomaly in the temperature. 

The Average temperatures will be ( ~0.5C) less than average normal temperature. Areas like Rajasthan-Gujarat border can experience lesser than avg temp by a factor of around ( 0.8C to 1C)

4] Northern Chattisgarh,Bihar and Jharkhand,West Bengal
Regions will witness a slightly cooler than normal winter conditions with average variation of about 0.3-0.5C ( lesser than the normal) 

5] Sikkim,NE India 

Though this shall not support the Deoras limit but it appears that the regions will witness warmer conditions with temperatures around ( 0.3 to 0.5C) more than normal 

6) Central,Northern,Eastern Maharashtra,
These areas will be witnessing normal winter conditions but the tendency shall be a slightly warmer than normal by a factor of around 0.3C. 

The expected record min temperature of Nagpur for the season shall be in the range of 7.5C ( +/- 0.5C)

7) Southern Maharashtra and remainder Southern India
Warmer than normal conditions with temperature variation of a factor of around ( 0.5C to 1C) more than Normal for Southern India

* No forecast available for Lakshadweep, Andamaan Nicobar Is.*
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7) References & Acknowledgements

http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/

http://www.apcc21.net/eng/service/fore/lmon/japcc030101_lst.jsp

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/nao.shtml#forecast

http://en.wikipedia.org/wiki/Arctic_oscillation

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/ao_index_mrf.shtml

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/ao.sprd2.gif

http://metdweather.blogspot.in/2010/11/2010-winter-forecast-for-india.html

http://metdweather.blogspot.in/2011/10/2011-winter-forecast-of-india.html

http://indiawaterportal.org/met_data/

http://ggweather.com/enso/oni.htm

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/hgt.ao.cdas.gif

http://www.apcc21.net/eng/service/fore/lmon/japcc030101_lst.jsp

http://nsidc.org/icelights/2012/02/02/the-arctic-oscillation-winter-storms-and-sea-ice/
http://weather.unisys.com/archive/sst/

2012 WINTER FORECAST FOR INDIA ( PUBLIC VERSION)

(C) 2012 AKSHAY DEORAS

metdweather.blogspot.com

All Rights Reserved.....

FOR MORE DETAILS, REFER TO THE TECHNICAL VERSION OF THE WINTER FORECAST 

From the Desk,

14th Oct 2012

0400hrs IST

Nagpur,India

Dear Readers, 

The Official forecast for the 2012 Winter in India is below.

This year's forecast is an experimental forecast as we have used a new technique for weather forecasting. Till the last year, the winter forecast used to be made using the weather models directly. However there are many errors in it which ultimately spoil the forecast accuracy. This year's winter forecast consists of two parts. One is a technical part having all the scientific background for the forecast whereas the other one is the non technical or the public version for lucid understanding of the people. 

As per the forecast, it appears that Northern half of the country will experience cooler than normal winter whereas southern half will experience warmer than normal conditions. As a result, the net forecast for 2012 Winter in India seems "NORMAL WINTER''

We also expect to cross the 2,00,000 pageviews after the Winter forecasts are published. 

Thanks for the support !

For any feedback/suggestion, you can mail me at metdweather@live.com 

Greetings! 

Akshay Deoras

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

*It appears that more or less a ENSO Neutral will persists through the Northern Hemisphere winter with a slight El Nino conditions emerging towards the year end.

*** NET AVERAGE IS CONSIDERED, INDIA WILL HAVE A NORMAL WINTER FOR THE SEASON***

Zone Wise- 

North India- 

1] Jammu and Kashmir,Himachal Pradesh,Uttaranchal

  Normal winter conditions will be observed here.The temperature anomaly ( All season Average) shall be around 0.2C to 0.1c less than average temperature.

2] Punjab,Haryana,Chandigarh,New Delhi

The overall temperature anomaly in these regions depends on the western disturbance. However it does appear that these regions will witness ( 0.5C to 0.7C) less than average temperature. 

After the snowfall events, temperature in the plains will drop suddenly but average will be near to the predicted value.

** We shall not estimate the number of western disturbances as its a debatable topic. However, the precipitation in the hilly areas seems NORMAL

3] Madhya Pradesh,Rajasthan,Uttar Pradesh,Gujarat 

A Cooling effect is likely in these areas as the jet streams coupled with the negative AOI influence shall lead to drop of temperatures due to more cool air incursion. 

** Uttar Pradesh will have NORMAL winter and hence I don't expect any anomaly in the temperature. 

The Average temperatures will be ( ~0.5C) less than average normal temperature. Areas like Rajasthan-Gujarat border can experience lesser than avg temp by a factor of around ( 0.8C to 1C)

4] Northern Chattisgarh,Bihar and Jharkhand,West Bengal
Regions will witness a slightly cooler than normal winter conditions with average variation of about 0.3-0.5C ( lesser than the normal) 

5] Sikkim,NE India 

Though this shall not support the Deoras limit but it appears that the regions will witness warmer conditions with temperatures around ( 0.3 to 0.5C) more than normal 

6) Central,Northern,Eastern Maharashtra,

These areas will be witnessing normal winter conditions but the tendency shall be a slightly warmer than normal by a factor of around 0.3C. 

The expected record min temperature of Nagpur for the season shall be in the range of 7.5C ( +/- 0.5C)

7) Southern Maharashtra and remainder Southern India

Warmer than normal conditions with temperature variation of a factor of around ( 0.5C to 1C) more than Normal for Southern India 

* No forecast available for Lakshadweep, Andamaan Nicobar Is.*

Predict the 2012 Winter Contest of METD WEATHER

To enable people's participation in Meteorology and particularly in the Weather of India, METD WEATHER announces a "Special Offer". The contest is named as "Predict the 2012 Winter of India". The contest is a very simple contest and definitely doesn't require any technical brains to answer. The participants also are not expected to be profession/passionate meteorologist or others having knowledge of meteorology. This will enable a common man to participate. 

As was announced, the 2012 Winter Forecast of METD WEATHER will be issued on Sunday,14th Oct 2012 at 1000hrs IST ( 0430hrs GMT). 

But what are the participants expected to do???

Simple, just predict what METD WEATHER's forecast will point at. Simple statistics imply that there are only three equally likely events for the 2012 Winter of India

Either- 

1) The Winter will be colder than normal

2) The Winter will be normal 

3) The Winter will be warmer than normal 

So the participant has to select any one of the option and follow the following procedure to submit their entry. 

What will winners get?? 

The person whose estimate matches with METD WEATHER forecast will get a chance to get featured on the METD WEATHER BLOG and also will get a chance to display his weather related story. Winners will be notified accordingly and will be asked to submit their weather story 

What are the steps to be followed?

Here is the proceedure an interested person must follow for getting involved! 

1) The person needs to comment on the 2012 overall winter for India in one line by mentioning whether he/she thinks that the winter will have ANY ONE OF THE BELOW NATURE-
1) NORMAL
2) WARMER THAN NORMAL
3) COLDER THAN NORMAL

STEP 2- 

After the person is firm with his guess, he needs to send a Facebook message

***

to METD WEATHER. 

The Facebook page of METD WEATHER is facebook.com/deorasakshay 

Those who aren't connected on our Facebook page need to just click the "Like" and then proceed. 

This can be done from any device. The person needs to open the Facebook METD WEATHER pageand click 'Message' option. He/She must comment in one line the option he/she feels from the above three and send it to METD WEATHER

STEP 3-
After you send a message to us, we will reply you thus confirming.

THE LAST DATE FOR THE SUBMISSION IS FRIDAY,12TH OCT 2012 1200hrs GMT. So the comments much reach before this

THE WINNERS WILL THEN BE NOTIFIED ACCORDINGLY AND WILL GET A CHANCE TO GET FEATURED ON THE BLOG WITH THEIR WEATHER STORY..

*** The comments must be messaged to METD WEATHER FACEBOOK. Commenting on the posts and thus submitting will not be considered!!!

So what are you waiting for????????

Regards,

Akshay Deoras

Owner,Severe Weather Forecaster

METD WEATHER

India

metdweather@live.com

Announcing the "2012 Winter Forecast for India" on 14th Oct 2012

METD WEATHER
Akshay Deoras
Severe Weather Forecaster

FOLLOW METD WEATHER FACEBOOK FOR THE LATEST UPDATES. 

The 2012 Winter forecast for India will be issued on Sunday,14th Oct 2012 at 1000hrs IST ( 0430hrs GMT). The Winter Forecast will be issued on the blog and the facebook page followed by a Scribd edition. 

This year's winter forecast will contain two parts. One will be a technical forecast for weather forecasters and the other will be a public version. A related graphic map also will be published!

Meanwhile, METD WEATHER declared the Monsoon withdrawal from Central India with it continuing across Western Maharashtra,Southern India and NE India. Some interesting weather is happening/going to happen in India. 

The Surface thai maps indicate a region of MSLP of 1004mb. The IR satellite imagery also shows extensive clouding across Eastern parts of Southern India especially across Andhra Pradesh ( over Hyderabad). The 850mb map shows that at the 850mb level,a low pressure will develop offshore Goa and vicinity coast. As this happens, till 4th Oct, heavy rains will occur across Northern AP,Northern Karnataka, Central and Southern Maharashtra. 

The parent 850mb low pressure will continue to remain offshore South Eastern India due to which an upsurge in the moisture level will happen across Central India. With better energetic conditions and moisture arriving, convective activity will trigger in these areas with thunderstorm rainfall expected in Nagpur in the afternoon hours till 4th Oct especially around 1-3 Oct. 

Stay tuned for the updates! 

Severe Thunderstorm rocks Nagpur, interesting weather expected

METD WEATHER
Akshay Deoras
Severe Weather Forecaster

On the late afternoon hours of 2nd Sept 2012, a very powerful thunderstorm passed through the city of Nagpur. The Thunderstorm which arrived from the NNE directions was one of the most intense I have ever intercepted with severe winds especially the wind gusts and blowing rainfall due to the winds. The lightning also was very severe with high frequency as well

In just 30-40mins from the initiation, the rains as measured at the HQ were 33mm whereas the IMD recorded 31mm.

Pre-Warnings regarding the thunderstorm couldn't be given as the Doppler Radar of Nagpur is NOT FUNCTIONAL SINCE NEARLY A MONTH WITH THE WARNING 40KVA EXTERNAL UPS UNSERVICEABLE as the visual based warning approach is restricted to only a short corridor of around 50km where one can't estimate the key factors like the Wind Velocity, Hailcore or the rainfall rate etc.. which only a Doppler Radar can do

This raises this big question that What help is the radar costing in crores giving to the City forecasters?

One can check the radar product here 

I have been asked many times since the thunderstorm what was the reason for it and why such thunderstorm happened despite of having an almost clear morning period.

The above is the 850mb ( Roughly 4000-5000ft) above the ground atmospheric condition as analysed at 12z ( 0530PM IST) on 2nd September 2012. One can see a giant region of anti-clockwise circles or spin. Such anticlockwise spin refers to a region of low pressure for Northern Hemisphere.

Hence one can conclude that there is a broad low pressure region offshore West Bengal-Odisha region as indicated by this cyclonic spin at that atmospheric profile.

The vicinity of such lows acts like a boon for such heavy rainfall events/thunderstorms as they get moisture from such lows from the Bay of Bengal hence forward referred as the Bay Low in this text.

The next ingredient of the Severe Thunderstorm Cookbook is the energy referred as the CAPE or Convective Available Potential Energy. The parcel of air needs some energy ( A Positive Buoyancy) for lifting. The more the available energy with no factors affecting like Wind Shear, the more will be the condensation of the parcel of air thus forming a cloud type called as CB or Cumulonimbus.

The CAPE in the region ( say 100km NE of Nagpur) was near to 2000J/Kg which is a significant value in terms of the instability is concerned.

So just after 12PM IST, CB clouds started developing NE of Nagpur due to all the favoured conditions out of which we discussed a few above. The CB clouds then approached Nagpur and if we had the RADAR product, I could have confirmed how strong the thunderstorm outflow was.

But why didn't it happen before? The main reason for it is the presence of the mentioned 850mb low pressure region offshore Odisha. It basically had triggered short pulses which later developed into thunderstorms and moved SW. This condition wasnt there in the last week.

Also the above Visible image from DUNDEE showing Nagpur ( Pink dot) just after the squall line thunderstorm passed. Its very clear from the geometry of the thunderstorms that they were linearly organised and a Squall Line Thunderstorm. This must have intensified the Thunderstorm outflow!


The station 42866 which normally records the data for Nagpur did't take any data for that period so I am evaluating the expected wind speed at that moment with the help of some experts. In my opinion, it must have been atleast 70-80km/hr!

Many big trees were uprooted in almost all the parts of the city. I could record a HD video of the event along with this solo picture of the fallen branch of the tree in my area-

Here is the HD video of the Thunderstorm.. Please watch the video in full volume to enjoy the nature's fury-

http://www.youtube.com/watch?v=wPSvXvOQ6lQ&list=UUlPxSYxAxMVg5tEUWRbpDIQ&index=1&feature=plcp

OR CLICK HERE

In the latest news, 5 people were reported to have died as the portion of the temple in which they were collapsed on them-

India Weather Update-

The biggest concern at the moment is from a region of a Positive Vorticity at the Mid Tropospheric levels as shown in the above GFS projected ( +72hr) base 12z,2nd Sept 2012 plot. 

The region is at present near North AP offshore. Its nothing but part of the above 850mb anticlockwise spin ( top most image). Thus one can see the region of Positive vorticity approaching Central India once again by Tue-Wed period. 

In that regard, 

Heavy to Very Heavy rains are expected in Northern AP-Southern Chattisgarh 

Even Western,Central AP and Eastern Karnataka will receive heavy rains during the same period i.e Monday and Tuesday 

The rains will then move into Southern,Central Maharashtra including Nagpur on Tuesday onwards continuing on Wednesday as well and gradually spreading into Central and NW Madhya Pradesh. 

Gujarat and Sindh region will get some rains from this system and another already present there around Thu-Friday.

Considering the robust instability present in Central India, Severe Thunderstorms may re-occur and hence you must follow METD WEATHER FACEBOOK PAGE for details

"Mysterious Clouding in the Southern Arabian Sea"??

METD WEATHER
Akshay Deoras
Severe Weather Forecaster

FOLLOW METD WEATHER ON FACEBOOK FOR THE LATEST WEATHER RELATED UPDATES. CLICK   HERE  TO JOIN THE PAGE 

I received a few questions today about the "mysterious" clouding in the Southern Arabian Sea. The attached image is of the DUNDEE Satellite Imagery (Meteostat) VISIBLE of  0.45 - 1.00 µm RANGE.

It clearly shows some continuous clouding stretching from Offshore South-Western Coast to South Central Arabian Sea.

The above IMD Cloud top temperature image indicates the cloud tops having a peak temperature as significant as -40C. More negative cloud top temperatures indicate that the convection happening in the system is very significant. 

But what is causing such clouding???

Let us check the 12z,25th August 2012 GFS forecast models for Mid Troposphere ( 500mb). 

The above is the GFS Analysis at 12z,25th Aug 500mb. One can see some red shaded regions EXACTLY AT THE SAME PLACE WHERE CLOUDING IS NOTED IN THE ARABIAN SEA.

Such red shaded regions indicate Positive Vorticity in the Northern Hemisphere. Positive Vorticity basically deals with the anti-clockwise flow or the movement of the air ( in Northern hemisphere) which is often noted at the base of troughs ( region with short geo-potential heights). Thus there is a PVA or Positive Vorticity Advection happening due to which the lifting of the air is boosted which in turn is responsible for such clouding in the Arabian Sea.

This is also confirmed by the 500mb Geopotential Height which is 585dam in that region as compared to the higher values in the same latitude around.

So far, at the surface level, no low pressure region has been reported in that area and hence following the methodology, one can't call this region as a depression!

WEATHER UPDATE_ 

There is another Bay system approaching India from the East. The above satellite images followed by the 500mb analysis and forecast suggests that the system has started its movement into India and the 850mb anti-clockwise circulation at the moment is over Odisha region with the MSLP of 1000mb as per the Thai Maps.

This system is expected to pass through ( the PVA region) Maharashtra-Andhra Pradesh-Chattisgarh border and head NW by 72hrs. The convection seems strong in the Northern periphery of this system and hence considering its path, Southern,Cent Chattisgarh,Eastern Maharashtra including Nagpur will receive rains though accumulation will be more towards Northern AP and Southern Chattisgarh till Tuesday.

Rainfall is now expected to decrease in Northern India considering no approaching system and arriving DRY phase of the MJO.

ENSO update- 

The SST in the Nino 3.4 region has reached +0.6C ( Anomaly) which is a classic indicator of the El Nino conditions but only from the point of view of SST anomaly. The atmospheric circulation in the region remains neutral or average and is slightly turning towards the Positive phase ( El Nino).

It can be expected that the ONI values for the period of JJA to be at the El Nino threshold and by Mid September to September end, the phenomena establishes in the Pacific Ocean.

I shall update later on that