West Bengal spared from heavy rains. Depression slams Bangladesh

METD WEATHER

Akshay Deoras

Severe Weather Forecaster

The strong tropical depression or Invest 95B which had threatened to West Bengal state spared the state. From the morning datas it was becoming clear that Depression w'd miss the state yet the warnings were in full swing with upgradation as Center of depression passed 100km away from Kolkata which is pretty close

The tropical depression caused very strong storm surge in Bangladesh coast . My Facebook friend Alam Shafiul who lives at Chittagong in Bangladesh told me that under the influence of this system, storm surge coupled with Natural tide led the sea level to rise 5-6ft above normal.

Strong Winds,Gale winds were also reported.

3 people were killed and 50+fisherman missing in Bangladesh

RELATED NEWS ARTICLE IS HERE

SINCE THE DEPRESSION NOW HAS LANDED OVER LAND AND CURRENTLY HAMMERING THE NE SEVEN SISTER STATES OF INDIA, CHANCE OF TROPICAL CYCLONE FROM IT IS ZERO WHICH I HAD MENTIONED IN THE PREVIOUS POST

NEW SUSPECTED LOW PRESSURE IN BAY OF BENGAL NEXT WEEK

WHAT LOOKS NOW ON COMPUTER MODELS IS AN EXCELLENT LOW PRESSURE SETUP COMING UP THE NEXT WEEK

IF THE GFS MODELS GO TRUE, ALL THE EXCELLENT CONDITIONS COMING UP IN NORTHERN BAY OF BENGAL

A TROPICAL WAVE MIGHT TRAVEL FROM THE EASTERN SEAS TOWARDS MYANMAR AND ENTER BAY. GIVEN SST,UPPER ATMOSPHERIC CONDITIONS, LOW

WILL MATERIALIZE TO A TROPICAL DEPRESSION AT LEAST AND HOPEFULLY A CYCLONE

A PICTURE OF THE 144HR GFS SEA LEVEL PRESSURE (144HR+00Z,08TH OCT 2010) HAS BEEN PUT ON THE BLOG.

IF THAT LOW BECOMES A CYCLONE THEN I MIGHT GET A CHANCE TO INTERCEPT IT IN NAGPUR AS IT WILL DEFINITELY TRAVEL THROUGH CENTRAL INDIA IF IT MAINTAINS THE TRACK

(RIGHT- THE EXPECTED TRACK OF THIS LOW PRESSURE. MORE TECHNICAL PLOTS WILL BE PUT AS THE SITUATION UNFURLS)

INVEST 95B LOOKS STUNNING IN BAY OF BENGAL

METD WEATHER

AKSHAY DEORAS

SEVERE WEATHER FORECASTER

The "So called Low Pressure 95B" is now INVEST 95B. Invest is a term used by NHC,JTWC for a system which is being monitored for Troipcal Cyclone Developments!

As was mentioned in my last post, The 95B had full signs of strengthening again in Bay given the warmer SST,movement away from wind shear and moist air mass!

In the newly arriving datas from CIMSS and GFS Cyclone prediction models and the satellite images, the system has organized both in symmetry and pressure wise and looks like a Classic Tropical Depression to me with surface winds enough to be marked in a Tropical Depression. However no confirmation yet.

JTWC has also upgraded their alert status and has mentioned a FAIR chance of Tropical Cyclone from this system and are monitoring it for a Cyclone

Forecast

As on today morning, INVEST is located very close to Digha ( EAST OF DIGHA in West Bengal and south of Kakdwip in West Bengal)

The air pressure at minimum is near to 1000mb as of 0530hrs,IST

Maximum surface winds as per JTWC are 20-25kt near to 46Km/hr

Heading-NE

The 0400hrs satellite imagery in infrared channel is depicting strong Central Dense Overcast(CDO) over the LLC or low level cyclonic circulation

The infrared image also showing some weak rainbands towards the SW of Low

The Water vapor channel image is showing that LLC has moved under the High Pressure ridge

The computer models are indicating that the Wind shears (Horizontal) will be very less on 8th Oct 2010 around this low pressure. Also a Low Convergence will build in the vicinity of this low as it surges NW.

THE BEST FEATURE IS THE COASTAL SST WHICH IS GREATER THAN 31C!

This is a very good feature for a system like this having a good divergent flow aloft to release latent hear.

UPPER ATMOSPHERIC CONDITIONS REMAIN VERY FAVOURABLE WITH STRONG CONVECTION HAPPENING AND CLOUD TOPS ALREADY -70C

(RIGHT- CIMSS PLOT SHOWING THE SST NEAR TO 31C OFFSHORE WEST BENGAL. THE I IN RED IS THE INVEST AREA AND THE CIRCULAR LINES ARE THE WIND SHEAR

NOTICE THE WIND SHEAR IS RELAXED NEAR "I")

METD WEATHER FORECAST-

I W'D NOT BE SURPRISED IF THERE COMES A CONFIRMATION ABOUT THIS SYSTEM AS A TROPICAL DEPRESSION.

IT WILL INTENSIFY BEFORE STRIKING BANGLADESH AND SEVEN SISTER STATES OF INDIA AND WEST BENGAL ALSO

( I THINK IN THE NEWLY ARRIVING DATAS WE WILL SEE THE LOW STRENGTHENING)

TROPICAL CYCLONE CHANCE- I THINK ITS LITTLE LATE FOR THIS LOW TO BECOME A TC. MUCH OF ITS PORTION IS ALREADY OVER LAND AND WILL BE CUT OFF SOON FROM WATER TEMP

CONSIDERING ALL

I UPGRADE THE ALERT TO MARK 5 ALERT AND A PDS FOR

WEST BENGAL EASTERN PORTION,BANGLADESH,7 SISTER NE STATES OF INDIA

ALERT WILL EXPIRE 12HRS,9TH OCT 2010

Heavy rains threaten more as low nears West Bengal!

METD WEATHER

Akshay Deoras

Severe Weather Forecaster

UPDATE ON THE LOW PRESSURE

THE 12Z THAI MAP HAS SHOWN THAT THE LOW AGAIN HAS BEEN INTENSIFIED TO 998MB! HOWEVER THE SYSTEM HAS LOST ALL ITS SYMMETRIC SHAPE DUE TO THE 10KT+ WIND SHEAR WHICH IS LOW BUT WHEN HELPED WITH ZERO CONVERGENCE AND DIVERGENCE IS EFFECTIVE

LOW TYPICALLY STRENGTHEN DUE TO MOIST AIR MASS FEED WITH LOW LEVEL CIRCULATION INTENSIFICATION WHICH HAPPENS AS MORE MOIST AIR RISES AND THEN COLLIDES WITH COOL AIR RELEASING THE LATENT HEAT

WITH THIS SETUP, PRESSURE WILL RISE ON 8TH OCT BUT I BELIEVE IT WILL STRENGTHEN SOME BEFORE HAVING A COASTAL LANDFALL ON 8TH

SO SYSTEM IS FULL OF SURPRISE

MARK III ALERT CONTINUES NOW IN REMAINING AREAS

MARK III ALERT FOR -

COASTAL ORISSA ( ESP- BALESHWAR,BHADRAK,PARADWIP ETC ON COASTS )

ALERT EXPIRES ON 00HRS,SATURDAY9TH OCT 2010 IST

ALERT FOR STRONG 45-50KM/HR WINDS ALSO

LOW PRESSURE WILL THEN SURGE NORTH-EAST AND MARK III ALERT FOR

SOUTHERN,CENTRAL WEST BENGAL

ALERT EXPIRES ON 12HRS,9TH OCT 2010

ALERT FOR STRONG WINDS ALSO

BANGLADESH-

HEAVY RAINS WILL CONTINUE ON 8TH OCT 2010 AND 9TH OCT 2010

MARK III ALERT ALSO IN EFFECT FROM NOW

DAMAGES IN ORISSA-

Due to strong gales and rains a disel streamer veered off in different direction near Dharma in Orissa.

Heavy rains also reported with gusting winds near the coast

Bay of Bengal low strengthening.Threatens Eastern coast for rains

METD WEATHER

Akshay Deoras

Severe Weather Forecaster

The featured low pressure in the bay of bengal 95B is strengthening.

As seen from the current 13:30 IST satellite image, the low pressure has massive -80C cloud tops.

AS ON 12Z,6TH OCT 2010

LOW IS POSITIONED AT 15.5N,85.5E

WINDS AT 925MB ARE 34KT(AS PER GFS WITH MIN PRESSURE AT THAT LEVEL NEARING TO 996MB)

EXPERIMENTAL MODEL- USE WITH EXTREME CAUTION

The Joint Typhoon Warning Center (JTWC) has mentioned a "Poor chance of Tropical Cyclone from it"

As featured in the 12z Thai map coupled with 12z GFS Cyclone models, the low now has intensity of 998mb! The computer forecast models are not in the agreement of further significant strengthening of this low since a well set 20kt deep layer wind shear with absolu

tely zero convergence present.

Also the thermodynamic conditions haven't improved with much towards a Weak symmetric warm core (as of symmetry) . The computer models also indicate that low will be dominant on 7th and then it will begin the extratropical transitioning

This system however will be very dangerous in terms of the rainfall which is likely to happen in parts of coastal Orissa,West Bengal and happening at Coastal AP,Tamil

Nadu with Pondicherry a

lso

All the alerts issued by METD WEATHER continue without any modification! Please note

MARK 3 ALERT IN EFFECT

"""Very heavy rains will hit Tamil Nadu,Pondicherry Eastern coasts along with Andhra Pradesh South Eastern Coast on 6th and 7th Oct 2010 that is Wednesday and Thursday

METD WEATHER issues a Mark 3 alert for areas PONDICHERRY,CHENNAI,KARKAIKAL

IN PONDICHERRY,NELLORE IN AP

Intensity of rains will be Moderate-Heavy in 6th and 7th as the low passes close

to them

THURSDAY,7TH OCT 2010

this LOW WILL NEAR EASTERN COAST OF ORISSA,WEST BENGAL

Very heavy rains will hit on 7,8,9, ( particularly on Friday,8th Oct 2010)

ALERTED AREAS INCLUDE NE ORISSA LIKE PARADWIP,DIGHA WEST BENGAL,HALDIA,KOLKATA,KHARAGPUR)

MARK 3 ALERT FROM METD WEATHER IN PROGRESS"""

Stay tuned for more updates

The Bay of Bengal Low pressure is likely to delay winter onset in Central India by a week

METD WEATHER

Akshay Deoras

Severe Weather Forecaster

What was looking like an onset of winter conditions over Nagpur in the last week is now gone. In the last week, the well set low offshore Karnataka had attracted winds from the northern parts of India as there were no other dominant air pressure. With the weakening of that stationary low having all stationary aspects in terms of Systems thermodynamic performance a new existing low pressure in Bay (Refer previous article) is shaping up. The initial North-West and later north surge of this low will pull off the NE Monsoon Retreating winds . Also associated with this low expected 1000mb by GFS,12z RUNS in few days will set up a more West-East 850mb winds towards this weekend with some straight N-S winds over Central India till this mid week.

Minimum temperatures which had fallen to 16C last week at Wardha and 20.3 C in Nagpur are already rising with lows nearing to 23C

I had mentioned that temperatures will drop again from this mid week in Central India but I now extend that period.

After that low vanishes the W-E winds over central India will be controlled by the movement of that existing low pressure offshore Karnataka. The Low as per GFS and ECMWF is expected to remain quite strong as it heads towards Gujarat the next week. As it does winds again will have a N-S tendancy pulling in cool air and dropping minimum temperatures at THE FULL SW MONSOON 2010 WITHDRAWAL PERIOD.

In all,

This week will be warmer than expected. I think temperatures will start coming down at minimum in Nagpur and Central India from mid next week

The Bay of Bengal Low pressure 96B details

METD WEATHER

Akshay Deoras

Severe Weather Forecaster

As was mentioned in the previous post,a low pressure area has already formed in the South-Western Bay of Bengal.

Expected air pressure of 1002 mb with this system stationed more towards the warm core symmetric side as shown by the 900-600mb thickness, this system is likely to intensify more given the mid-upper level thermal air tendancy of shallow warm core at the upper levels

(EXPERIMENTAL MODEL- USE WITH CAUTION)

GFS expects this low to feature 1000mb at minimum and be more towards a Warm core setup but the intensity will remain less as the forecast models are indicating a shallow warm core at upper levels till 10th Oct.

Tropical Cyclones require Deep Warm core for development and reach peak intensity during this phase. Then Extratropical transition stage begins

Well defined Low level circulation also exists with this system with UAC also

EFFECTS OF THIS LOW

The path of the low pressure seems to be just on track NW since the 200-300mb Steering winds have that type of flow.

Very heavy rains will hit Tamil Nadu,Pondicherry Eastern coasts along with Andhra Pradesh South Eastern Coast on 6th and 7th Oct 2010 that is Wednesday and Thursday

METD WEATHER issues a Mark 3 alert for areas PONDICHERRY,CHENNAI,KARKAIKAL IN PONDICHERRY,NELLORE IN AP

Intensity of rains will be Moderate-Heavy in 6th and 7th as the low passes close

to them

THURSDAY,7TH OCT 2010

THIS LOW WILL NEAR TO EASTERN COAST OF ORISSA,WEST BENGAL

Very heavy rains will hit on 7,8,9, ( particularly on Friday,8th Oct 2010)

ALERTED AREAS INCLUDE NE ORISSA LIKE PARADWIP,DIGHA WEST BENGAL,HALDIA,KOLKATA,KHARAGPUR)

MARK 3 ALERT FROM METD WEATHER IN PROGRESS

The entire forecast depends on the low pressure movement and can be changed as per the new model runs!

How Winters work in India

The 850mb wind map. Note the giant anticyclonic circulation in Bay of Bengal and the N-S winds

METD WEATHER

Akshay Deoras

Severe Weather Forecaster

The NE Monsoon or Monsoon withdrawal is on its half way! The 850mb GFS indicating that SW Monsoon has totally moved away from Northern India,Rajasthan, Gujarat,Western Madhya Pradesh,Weak in Uttar Pradesh,Madhya Pradesh East,West Bengal,Orrissa,

Monsoon is now moving away from Nagpur and surroundings and will take 48hrs more to withdraw from Nagpur.

(ALL AS ON 00Z,2ND OCT 2010)

Due to this, Rainfall already has started decreasing and mostly nil at the places where it withdrew.

Winter.

The Minimum temperatures are falling over Central India,Madhya Pradesh as a result of the cool air incursion over the Central India from the north.

As happens during the onset of winter, A High Pressure area stars building over Tibet due to strong cooling of the land as as cool air doesn't rise much as compared to warm air given its mass and density. As this happens, a Sea Level High Pressure of 1022-1024mb forms over Tibet.

At the same time low pressure areas gets created in the seas around the earth since heating of sea water causes a low pressure area to form. Due to this, the low level winds or the 1000-700mb winds blow from High pressure over Tibet towards Central India and then southern India. A High pressure area over tibet also blocks the jet streams causing it to split into two paths. One branch directly digs in India while the other blows as westerlies

Thus cool air from Himalayas digs inland and causes winters over Central India,eastern India and southern India,along with non coastal areas in Western coast

Current conditions

The High pressure over Tibet 1022mb and two low pressures of 1006mb over southern India and the Arabian Sea (few kilometers offshore Karnataka). Due to this cold air already had swept across Nagpur and other parts of Vidarbha,Central India causing minimum temperatures nearing to 20C since the last 96hrs. The minimum temperature was recorded at Wardha on 1st Oct 2010 which was 16C. Nagpur recorded a temp of 20.3. 16.4C was found at Yavatmal

Forecast-

The 850mb winds are not aligning North-South over Central India since the forecast models now indicate the low pressure in Arabian to shift slightly west.

Temperatures (Min) will rise by 2-3 C in Maharashtra. However Central and Northern Madhya Pradesh will witness same temperatures at minimum

Temperatures in Central India will again start falling down from Wednesday as a New giant Low level circulation or LLC forms in a wide area in Bay of Bengal on Thursday. The winds will regulate North-south again and cause temperatures to fall by 2-3C again

The SW Monsoon will withdraw completely from India by 15th Oct 2010