Friday, December 28, 2012

Major Weather change expected in Central,Southern India

Akshay Deoras
Severe Weather Forecaster,

Nagpur recorded a minimum temperature of 6.3C on Wednesday,26th Dec 2012. However there is going to be a major weather change in the coming days in India

Bay Low Pressure system-

Attached is the 850mb GFS Map of Base 00z,28th Dec.

One can see a broad patch of anti-clockwise winds with green shading across Sri Lanka. This is the Bay low pressure system which shall pump moisture across mainland of India resulting into precipitation in the southern states-

Above is the +48hr precipitation forecast showing rainfall across Kerala,Tamil Nadu,Coastal Andhra Pradesh and some interior Karnataka.
The precipitation shall increase across Karnataka coastal areas eventually spreading into Goa on the New Year eve

If does appear that Goa may get light rain spell on 30th Dec 2012 and some on 31st Dec as well. The meteograms aren't agreeing however..

As the Bay system progresses westwards, a High Pressure system is expected to develop across Orissa at the 850mb level which shall steer the moisture and push it Northwards.

Minimum temperature in Central India will be rising nowonwards as the direction of the winds have changed.

The precipitation will spread into Southern Maharashtra with areas like Pune and subsequent interior Western Maharashtra will receive rains with rise in minimum temperature.
This shall happen on Monday,31st Dec 2012.

Pune which witnessed a min temperature around 7C shall have relatively warmer nights though a heavy rainfall event is unlikely due to the scattered precipitation tendency there..

As the moisture pumps further, it shall weaken in terms of Relative Humidity (RH) however be that much to bring cloudy skies in Nagpur and Central India.

The min temperatures will rise to around 15-17C in Nagpur taking away the winter effect in the city. Due to moisture amounts and slight unstable atmosphere, clouding shall be there in the city during ( Partial) 31st Dec and then increasing on 1st and 2nd Dec ( As of present GFS).

However, there seems to be a little problem with the initial Skew-T of that period
Above is the 1st Jan 2013 SKEW-T for Nagpur region. Its clearly visible in those indices that CAP or CIN will be greater than the CAPE ( CIN = 102 J/Kg)..
This situation depicts a non buoyant atmosphere where due to thermal inversion, buoyancy is lost thus a parcel of air ( moisture embedded) will sink as it rises due to which chance of convection and thunderstorm looks minimal now
However, the SKEW-T can change and moreover such CAP can break if there is abundant sunshine in the morning on the 1st Jan.

Situation on this rainfall event shall be more clear in the coming period

GFS shows a precipitation in Nagpur ( which then must be non convective) on 1st and 2nd Jan

Trace Amt rain can be expected on 31st Dec night ( As of 28th Dec GFS)


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