Thursday, July 14, 2011



BB3, as seen in the Thai map, has moved inland, and as on Thursday evening was a weak low over south Chattisgarh and adjoining Vidharbh. IMD report also confirms this.

Yesterday we had forecasted good precipitation in interior Mah. and N.Gujarat. Well, these regions were blessed.
In N.Gujarat, Dangs reported 27 cms and Kaprada 21 cms amongst the heavy weights. Vortex over Marathwada (see blog) is weakening.
Marathwada region had heavy rain, with Udgir recording 16 cms and Jalkot 13 cms.till Tursday morning.
In Konkan belt, highest was at Ulhasnagar recording 19 cms and Thane 18cms. and several places between 14-16 cms. The rainiest spots in Konkan.
Vagaries had estimated a few places with 15 cms. Panvel measured 13 cms. All till Thursday morning.

On Thursday, rainfall moved into E.Rajasthan and North M.P. regions.

The Monsoon axis at sea level runs thru Rajasthan, M.P. and then southwards into the low pressure (BB3).
The upper level troposphere axis runs thru North Arabian sea thru Mah. and North A.P. This is keeping the SWM active over the region

Upto Thursday morning, Mumbai measured up 93 mms and 57 mms at S'Cruz and Colaba, averaging 75 mms for the city. (Exact estimation by Vagaries).

Mumbai had heavy showers pre noon, with a decrease in intensity after around 1 pm. Till the evening, the city measured 44.mms and S'Cruz 84mms. The other AWS stations mesured between 35 mms (Worli) and 65 mms during the day. (Vagaries estimate 35-40 mms).

Lakes got copious rainfall, with Tansa notching up 20 cms.

Thursday Night will be wet with heavy showers. But, showers are expected to "slow down" after around 2 am (Friday morning). Satellite townships expected to witness real heavy downpours around mid night, reducing gradually by morning.

Friday will be cloudy, with bright intervals. Much less rainfall as compared to Thursday, with a few 3/4, heavy showers of much lesser duration. Rain amount average 30 mms.
Saturday/Sunday: Parly cloudy with sunny intervals. Some heavy passing showers, giving an impression of a rainy day, but stopping abruptly. Rain amounts 20 mms per day.

Interior Mah. will be drier from Friday, as the Vortex fizzles out. A distinct decrease in rains in Marathwada from Friday, but BB3 will precipitate some thunder showers in Vidharbha on Friday, only to decrease from Saturday. BB3 is showing clouding in the western and SW segments.

Pune will be partly cloudy on Friday. Week end will be cloudy with sunny intervals. Light drizzles and very light showers in parts of Pune.

For Nagpur, a showers or two on Friday. Clearing after Friday evening. Cloudy on the week end with drizzles in some parts.

This week's UAC over Gujarat was expected to shift westwards, and benefit the Sindh coast of Pakistan. But the system got stuck over the Gujarat region for 2/3 days, and got embedded in the upper level monsoon axis.

Expected to push some clouding into Karachi on the weekend. Except for some traces of rain in some areas, no rains expected till Monday in Karachi.
Hyderabad (Sindh) will be dry and temperatures in the 40s during the weekend.


12 comments:

Anonymous said...

is it not weird that orissa and chatisgarh has been relatively dry last two days, the place of actual low pressue ?

Ananth

svt said...

I will be surprise if dadar didn't got more than 100 ml of rains from 6:00 am in the morning to 11:00 pm in the night. Two particularly heavy downpour happend 1) between 10 am to 1 pm 2) between 8:30 pm to 11:00 pm. Hard to believe that just feeble low brought this kind of rains in north konkan. Anyway few forecast models indicating heavy rains might return to mumbai by next tuesday/wednesday. But its too early to predict exact volume of rains.

rajesh said...

svt.according to me, which i have put up in vagaries, this rainfall was due to off shore trough activation. Never due to BB3. Have explained it almost daily, step by step on blog.
As per AWS, Dadar got 60 mms during the day today. My rain guage at warden road measured 58 mms.

NT said...

Rajesh, couple of things that I find a bit strange about the current rains, as rightly pointed out by Ananth, the states of Orrisa and Chhatisgarh were very dry, infact one could hardly see any cloud cover, you also mentioned in your blog that the LOW is devoid of any cloud cover around it, that is really strange. Also, I noticed that BB2 and BB3 both formed around central BOB - North Andra / South Orrisa coasts, typically this happens in either forming or retreating Monsoons, in peak Monsoon period like mid-July, one would expect LOWs / Depressions to form around N - Orrisa / WB coasts, may be this is due to the fact that the Monsoon trough was South of it's normal position. The third thing that is the rains in Mumbai last couple of days, is this kind of rainfall just due to trough activation normal? In any case I thought the Offshore was activated last week itself, there were very heavy rains till Saturday and they resumed since Monday night (SCZ recieved 3 inch rain Monday night of this week), so never really thought the trough was de-activated. What's your take on the above?

rajesh said...

nt: Firstly the off shore trough matter.Things will be easier for me to explain if you would plz go thru the Saturday blog. Have mentioned the off shore trough weakening, and the 3 things required to get rainfall again.Was expecting trough to pick up on Sunday, but was late, and the picture was "not rosy" as mentioned by me, and for whch you acknowledged.In fact on Sunday, vagaries mentioned of a ridge in the northern part of the trough.
Have also explained on Tuesday, that there will be heavy rainfall in Konkan due to an UAC embedded in the off shore trough. Thus the extreme rains.
Abs normal for low to form off .P. coast, and better in fact.
Most of the clouding rushing from the Arabian Sea to BB3 has been grabbed by the Vortex en-route over Marathwada. See Monday/Tuesday blog.
Feel free to ask, will answer to the best of my ability.Always most of the explanations are given when i put up mu forecast.

Anonymous said...

Rajesh i wanted to ask can this low be able to make its way towards sindh coast or it will fizzle out just in between like previous ones ???

NT said...

Thanks for the clarifications, Rajesh, get your point. Had some incorrect beliefs, they are clarified now.

Anonymous said...

Its been a productive week for Mumbai lakes, just checked mumbai lakes almost Appx 45 % of full capacity( 5 months of water i guess). A bright spot in waht was otherwise a tragic week for mumbaikars
Pune situation not so rosy, just 30percent full

Ananth

Kaneyen said...

Rajesh, couple of things that I find a bit strange about the current rains, as rightly pointed out by Ananth, the states of Orrisa and Chhatisgarh were very dry, infact one could hardly see any cloud cover, you also mentioned in your blog that the LOW is devoid of any cloud cover around it, that is ......BY NT
-------------------------------------
Dear NT,
During SWM periods especially in India two wind branches will be dominant. One is Arabian SEa Branch and the other is Bay of Bengal branch. Climatologically speaking SWM will be active along 14-15 degree parallels. During this SWM 2011 Arabian Sea branch is relatively active and sometime vigorous than Bay branch. Even though there is no periodicity of Arabian Sea activeness, there are several historical evidences where Bay branch is weak. This may be inferred from the heavy rainfall distribution.
No cloud cover will be seen around the eye of the LOW. Usually during SWM period the formation of LOW in BOB will enhance rainfall in West Bengal, Odissa, MP, UP and interior land when the low is moving along the monsoon trough. The traditional monsoon trough from Ganga Nagar to Head Bay is NOT pronounced. During this SWM2011 period this trough is bleak and most of the time the orientation is distorted and confined to North to South direction in SLP CHARTS. However the Mid Tropical Circulation [MTC] and UACs are prominent.

Anonymous said...

I feel sat & sun will be heavier than what Rajeshbhai is expecting !!...........potey

rajesh said...

Kaneyen, thanks for the details and explanation to NT.
BB3 has been without clouds, with minimum clouding initially in the western quadrant.
Today, with BB3 over M.P. it is suddenly enveloped with clouding.

Anonymous said...

Will it reach souther sindh or give some rains here