Sunday, September 21, 2014

21st September....Autumn Equinox for the Northern Hemisphere...( See Weather Report Below the Article)

Seasons are opposite on either side of the equator, so the equinox in September is also known as the "autumnal (fall) equinox" in the northern hemisphere. However, in the southern hemisphere, it's known as the "spring (vernal) equinox".

There are two equinoxes every year – in September and March – when the sun shines directly on the equator and the length of day and night is nearly equal.

The Earth's axis is always tilted at an angle of about 23.5° in relation to the ecliptic, the imaginary plane created by the Earth's path around the Sun. However, the tilt's orientation changes throughout the year. On any other day of the year, the Earth's axis tilts a little away from or towards the Sun. But on the two equinoxes, the Earth's axis tilts neither away from nor towards the Sun and is perpendicular to the Sun's rays, like the illustration shows.

Why is it called equinox?

On the equinox, night and day are nearly exactly the same length – 12 hours – all over the world. This is the reason it's called an "equinox", derived from Latin, meaning "equal night". However, even if this is widely accepted, it isn't entirely true. In reality equinoxes don't have exactly 12 hours of daylight
At the equinoxes, the sun appears overhead at noon as seen from Earth’s equator.
That’s why the sun rises due east and sets due west for all of us. The sun is on the celestial equator, and the celestial equator intersects all of our horizons at points due east and due west.

The September equinox occurs the moment the Sun crosses the celestial equator – the imaginary line in the sky above the Earth’s equator – from north to south. This happens either on September 22, 23, or 24 every year...It varies from place to place...
Although the equinox happens at the same moment worldwide, the clock times vary by time zone.
For example: September Equinox in India is on
Tuesday, 23 September 2014, 07:59 IST.

World on 21st September 2014: 
The Hottest Place on 21st September 2014 was Sulaibiya in Kuwait and Ain Beida Airport in Algeria at 45c.
Highest Heat Index: 53.6c: Sirrri, Iran.

Maximum Pressure: 1082 mb  at Eagle Range, UT, U.S.
Minimum Pressure: 978 mb at Nuuk, Greenland.

Hottest in India: Hissar 37.7c.
Hottest in Pakistan was Sibbi at 41c.
Hottest in Nepal: Bhairawa Airport: 34.5c.

The Weather Report:
The SWM had withdrawn from Pakistan and now from West Rajasthan and Kutch. Gradually withdrwaing from Punjab and Rajasthan by 23rd. 

The Low from the Bay has almost fizzled out and merged in the axis. The UAC remains over North Bengal and Sikkim.
Cooch Behar in Northern Bengal bordering Sikkim  got very heavy rains of 16 cms on Sunday 21st in 9 hrs till 5.30 pm IST.

A Line of Wind Discontinuity will form in the Southern Peninsula interior region by 23rd. A pulse from the Bay will form a Low in Interior Karnatak around the 23rd.
Rains increase in Interior Karnataka and Maharahtra.

The WD mentioned in Friday's post is on schedule to form around the 25th in Northern Pakistan. 
From Vagaries

Weather Instagram at September 21, 2014 at 05:39PM

#chennai - 5:34pm, sharp shower now over polichalur zone. #weather

from Instagram

Weather Instagram at September 21, 2014 at 04:02PM

#chennai - 3:10pm, showers possible, lots of mini showers have popped over NW from city. #weather

from Instagram

#Chennai - 2:10pm, mini showers has popped over N-W from city around 40 to 65km.
T shower may(30% chance)  push into suburbs, city in 4hrs

Past 12hrs satellite IR loop suggests "Heavy rain over East India due to 98B" ... 

1:30pm, Rain continue over Jharkhand, S,central Bengal, N Odisha, S Bihar as 98B slowly weakens ... 

Latest analysis show that 98B has weakened and now over Jharkhand and adjoining W,central,S Bengal ... 
Mid-level circulation of 98B is also seen in same location ...  >> and its trough can be seen South upto W Bay.
In next 24hrs, 98B is expected to fizzle out completely ... 

On Tuesday, a N-S trough at low-levels from N-N-E Bay to S-tip Tamilnadu (along S-E coast) is expected ... 
23-Sep, a low-level (800hpa) anti-cyclone is expected over W,W-central Madhyapradesh (Sign of monsoon withdrawal)
Monday - South peninsula is going to get active with T showers with the formation of N-S trough and a circulation expected on 24-Sep.

On 23-Sep, a weak upper-level circulation may form over E Uttarpradesh, Bihar and drift East ... 

Rainfall alert for next 42hrs

Before morning of 22-Sep...
HEAVY scattered rain due to 98B over Jharkhand, Bihar, N,central Bengal ... 
Before midnight today...
Scattered T showers for N,N-W,N-central,N-E Tamilnadu into S Karnataka, S Andhra .. 
#Chennai - After 6pm, a T shower may push into suburbs, city before 4am, 22-Sep.
Around midnight, T shower may pop over S-E Tamilnadu coast as well !!

from noon till midnight, scattered HEAVY T showers for S,S-central Karnataka, S Andhra, N,central,W Tamilnadu, W-ghats Kerala.
22-Sep... T showers will pop along W-ghats of Karnataka and upto S-tip Tamilnadu ... 
T showers expected to persist over Odisha, Jharkhand and into S,central,N Bengal !
Heavy over N,central zones of N-E states !