Wednesday, July 14, 2010

Rains lash parts of north-west; heavy downpour in east

Many parts of north-west, east and east-central India continued to receive heavy to very heavy rainfall during the 24 hours ending Tuesday morning.
An India Meteorological Department (IMD) update said that fairly widespread rainfall has occurred over the west coast, Assam, Meghalaya, Bihar, East Uttar Pradesh, Vidarbha and east Madhya Pradesh.

It was scattered over coastal Andhra Pradesh, Gangetic West Bengal, Chhattisgarh, Punjab, Haryana and Himachal Pradesh.
South-westerly strong winds carrying moisture from North Arabian Sea continue to blow inland over Gujarat and Rajasthan in the lower levels of the atmosphere.
The western disturbance over Jammu and Kashmir and neighbourhood has continued to persist as an upper air system.
It could hold on to its position for another two more days.
In another good augury for central and east India where the rainfall has been varying deficient thus far, the axis of the monsoon trough is likely to shift southwards during next two days.

This indicates building activity in the Bay of Bengal, and numerical weather prediction models have suggested the formation of a low-pressure area over the northwest Bay by Wednesday.
Scattered rain or thundershowers are likely over Chhattisgarh, Madhya Pradesh and Vidarbha during next 24 hours and increase thereafter, the IMD said.
A warning valid for the next two days said that isolated heavy to very heavy rainfall would occur over Assam, Meghalaya, West Bengal, Sikkim, Orissa, Bihar, Jharkhand and East Uttar Pradesh.
Meanwhile, northwest Pacific has already thrown up a typhoon, named Conson, which is bracing to hit the Philippines.

Conson is forecast to enter the East China Sea later and head towards the eastern coast of mainland China. Conson may briefly lose typhoon status after hitting the Philippines, but after entering East China Sea, it could undergo another round of intensification, according to international models.
This could have implications for Indian monsoon, since it would be forced to part with some of the moisture to a much stronger system taking shape in the same equatorial seas. The US National Centres for Environmental Prediction (NCEP) has indicated that the ‘low' forming in the Bay of Bengal may move west to cross Orissa coast but not go far beyond central India.

An IMD outlook valid till Friday said widespread rain or thundershowers is likely over West Bengal, Sikkim, Bihar, Jharkhand and East Uttar Pradesh during the next two days.
Fairly widespread rain or thundershowers would occur over the Northeastern States, Lakshadweep, the west coast, Andaman and Nicobar Islands and Orissa.
Scattered rain or thundershowers is likely over Jammu and Kashmir, Himachal Pradesh, Uttarakhand, Punjab, Haryana, Chandigarh, Delhi and West Uttar Pradesh on Wednesday but may decrease thereafter.
The International Research Institute (IRI) for Climate and Society at Columbia University has maintained the outlook for occasional rains lashing an arc from northwest to east India during the rest of the week.
The arc would extend from Gujarat into parts of Rajasthan and the rest of northwest India before becoming increasingly wet over east India.
The Fleet Numerical Meteorology and Oceanography Centre of the US Navy, too, has indicated that the wet session in the region would pan out along these lines.
As one reader has mentioned, the rainfall in this strategic region is very poor. Mahableshwar, the "water reservoir" of Maharashtra, is very important as it originates 5 rivers from its catchment. The most prominent, The Krishna river flows from the Mahbleshwar catchment down through the plains of Satara dist. rest of Maharashtra, thru A.P. into the Bay. The entire south Maharashtra and Ksishne Basin region of A.P. depends on the rains in this station.
This year, 2010, the station has recieved 890 mms till date, 14th. July, against a normal of 1920 mms required till date.
Last 3 years, end July totals are:
2006: 4733 mms
2007: 2118 mms,
2008: 1200 mms,

2009: 2662 mms.

The driest July was in 1899, with1084 mms during the month.
The highest ever seasonal rain was 10221 mms (1896)
and the lowest 3545 mms (1899).

But the rains are scanty in the ghats, and even though nearby Pune (60 kms away, but on the plains) has recieved 325 (+116) mms, and Satara, 60 kms away in the plains recieved 269 mms (_33). But,the actual rain days are less.
Rain days diagram of Pune and Mumbai (Coastal city) for rainy days comparison).
Another station, Lonavala, is also weak in rains this year.
As on end June, the rainfall there was 437 mms.
Last few years comparison of June shows the situation there.

2008: 1187 mms,
2009: 175 mms.
2010: 437 mms

What actually brings rains to the western ghats are depressions from the bay, not off shore troughs. Normally there should be at least 1 in June and 2/3 in July.This year, we have had none, and got 2 weak systems, that too UACs. Surprisingly, depressions are in drought this year, as are Pacific typhoons !
RT @EcoSeed: Manure helps power new army barracks RoyalHorseArtillery horsemanurepower
RT @EcoSeed: India climate meet ahead of Mexico to push tech deal Indiaclimatetalks MajorEconomiesForum
Good weekend rains over Gujarat ... !! ...
Internal Waves in the Indian Ocean ...
Heavy Rain in Bangladesh and India ...

Internal Waves in the Indian Ocean

The steady crash of waves pounding the shore draws vacationers to beaches across the world when temperatures climb. Driven by the wind and tides, these familiar waves ride across the top of the ocean. But deeper waves also move through ocean waters, visible only from their influence on ocean currents. These waves are internal waves, and they run through lowest layers of ocean water, never swelling the surface.
This image shows both internal waves and surface waves on the Indian Ocean near the Andaman Islands. The active Barren Island Volcano, part of the Andaman Islands, is shown emitting puffs of steam on the left side of the image. The Advanced Land Imager (ALI) on the Earth Observing 1 satellite acquired the image on March 6, 2007. Sunlight reflecting off the water’s surface gives it a pale, silvery blue color. The tiny wrinkles running roughly horizontally across the ocean are surface waves. Internal waves paint long diagonal lines across the ocean on the right side of the image.
Internal waves happen because the ocean is layered. Deep water is cold, dense, and salty, while shallower water is warmer, lighter, and fresher. The differences in density and salinity cause the various layers of the ocean to behave like different fluids. When tides drag the ocean over a shallow barrier such as a ridge on the ocean floor, it creates waves in the lower, denser layer of water. These waves, internal waves, can be tens of kilometers long and can last several hours.
As internal waves move through the lower layer of the ocean, the lighter water above flows down the crests and sinks into the troughs. This motion bunches surface water over the troughs and stretches it over the crests, creating alternating lines of calm water at the crests and rough water at the troughs.
It is the pattern of calm and rough water that makes the internal wave visible in satellite images. Calm, smooth waters reflect more light directly back to the satellite, resulting in a bright, pale stripe along the length of the internal wave. The rough waters in the trough scatter light in all directions, forming a dark line.

Heavy Rain in Bangladesh and India

Heavy monsoon rains pounded India and Bangladesh in early July 2010. The Integrated Regional Information Networks (IRIN) reported that more than 600,000 river island residents had been marooned, and thousands of hectares of farmland had been destroyed in Bangladesh by flooding. Meanwhile, CNN reported that monsoon floods had killed at least 221 people, and affected a million more in India since June 1.
This color-coded image shows rainfall amounts in India, Bangladesh, and the Bay of Bengal from July 6 to 12, 2010. The heaviest rainfall amounts—400 millimeters or nearly 16 inches—appear in dark blue. The lightest amounts—50 millimeters or less than 2 inches—appear in light green. The heaviest rainfall amounts appear concentrated in northern and eastern Bangladesh, although still substantial rainfall amounts affect a much larger area.
This image is based on data from the Multisatellite Precipitation Analysis produced at Goddard Space Flight Center, which estimates rainfall by combining measurements from many satellites and calibrating them using rainfall measurements from the Tropical Rainfall Measuring Mission (TRMM) satellite.
Chennai - Touched a max of 36.2 C (1:42pm).. now 4:15pm we have good low cloud formation. Shower chances are increased to 85 percent.
The UAC embedded in the axis is positioned over east U.P. and north-est MP. Rains in the region may can continue for another day.
The W.D. over North-West India and neighbourhood has continued to persist as an upper air system, and couldstay put for another two days.
This may result in moist south-westerlies interacting with the W.D. and bringing rains to the north-west region next couple of days.
W.D. or monsoon, rains are always welcome and needed.

Also, as mentioned yesterday, the monsoon trough is likely to shift southwards from Thursday. Central peninsula regions could then hope for a renewed spell, especially M.P.
Some models forecast an UAC forming over west/central M.P. around Saturday. This could result in good weekend rains over Gujarat. Also, we could see the northern end of the western off shore trough gaining strenght around weekend on the North Konkan/south Gujarat coast.
FAQ about the west coast: West coast will continue to get the on going moderate rains till Sunday, after which I expect some increase.

Mumbai: Same estimate of moderate 20 mms of rain, in sudden showers, Thursday thru Saturday.
Increase in rain frequency with heavy spells on Sunday/Monday, with around 40-50 mms of rain .

Yesterday in the blog, I mentioned that weather prediction models have estimated the formation of a low over the Bay by the 20th. and the
The Pacific has formed a typhoon, named Conson, which is bracing up to hit the Philippines. Conson, may stike Phillipines and after entering East China Sea, it could undergo further intensification,
This could have implications on the low in the bay. NCEP has also mentioned the formation possibility. (Some models/IMD mention of a low forming as early as Thursday. I personally think it could be around the 19th/20th).
Exclusive Shimla Monsoon Packages ...
11:30am, N. Bay is active, Showers over Coastal Orissa, More showers expectd over Chatisgarh, M.P and U.P today..
11:30am, Coastal Karnataka and coastal Maharastra are getting some scattered showers ..
Heat back in Delhi ...
RT @rajugana: @weatherofindia Baroda:9.25AM, overnight showers, now clear skies, sunny, sultry and without any cloud movement.
‘Off-shore wind farming could ease power crisis’ ...