Friday, April 27, 2007

Monsoon Watch -8

As anticipated, and required, the low temperature phase of Maharashtra has disappeared. In fact the temperatures have suddenly jumped, and gone above the normal. From a minimium of 20.6° a few days ago in Aurangabad, today's minimum was 29.2°, and Pune has risen from 16° (-5) to 22°(+1). The days were very hot too in Maharashtra,with Nagpur and Akola at 44°.

The sub continent as a whole has started heating up rapidly, and there were 2 places with 45° in Pakistan today, 5 places in Pakistan and 2 in India recording 44°, and at least 12 places with 43° in both the countries !

According to Jim(Accuweather), the high pressure in the upper altitudes favours the heat wave, and the next week may see the heat increasing. A few hot spots in Rajasthan and Sindh (Pakistan) may see temperatures at 47°, most parts of Gujarat and Maharashtra should also witness intense heat ,with many places in these states going to around 43-45° next week.

This favours the intensifying of the "low" over N.India to spread westwards and deepen to at least 1000 mb from the present 1004 mb.(Must reach 994 mb just before Monsoon).

By now, most of the central and southern Bay has heated to 31°. So the formation of a" low" in the first week of May seems likely.

Even most parts of the Arabian Sea , except the Northern areas, are at 31°. Constant sea temperature at 31 -32 °, should help pull the cross equitorial winds, maybe in another 15 days.

If the conditions are maintained, and the Arabian Sea remains around 32-33° till end of next month, the South West moisture laden monsoon winds from the African coast will be rushing into Kerala in the last week of May. And due to the warm sea, initial phase should be heavy along the west coast,and maybe coastal Gujarat.

Wednesday, April 25, 2007

Monsoon Watch - 7

With the "high" aloft, the day temperatures are bound to show a rising trend in the Northern Sub-continent in the next few days.This will do well for the "low" developing in N.India. As yet the seasonal "low" shows a pressure of 1005mb. Just before the monsoon sets in, in early June, this seasonal "low" will ,and should, drop to 994mb.,and stretch from N.India to Arabia, with its centre at Jacobabad,Pakistan.

Even the Bay has started heating, and the South east portion is now around 31°, also the south Arabian Sea is at 31° .Hints of the first pre monsoon" low" in the bay, maybe by first week of May, may be seen. This would be a bit late, but continuation of excessive heating in the bay and over India/Pakistan, could bring the monsoon by the end of May.

An interesting feature noticed in the last 2 days was a "cold wave" in Maharastra. Minimum temperatures were below normal, since the last 2/3 days by as much as 5-7°. Nasik and Pune were at 16°, Aurangabad at 20.6°,and a few days back, Mahableshwar was at 13°. Something worth noting was that today Pune and Shimla both recorded a minimum of 16.2° !

But, hopefully, this is just a very temporary phase,and temperatures dropped because of the skies clearing at night. This moderate spell of "low temperatures'' should not go on beyond a couple of days, nor extend area wise, as it may upset the Monsoon calender.

Sunday, April 22, 2007

Monsoon Watch- 6

There has been a good activity of thunderstorms in the central and southern peninsula in the last few days. An "oft and on" continuation of this, for another month, will gradually result in a good increase in the moisture level and heat condensation level in the atmosphere, and a further heating of the region will help in moisture holding capacity. If this condition sustains for another month, it should clear the way for monsoon flows to establish by the last week of May.

The IMD,in its monsoon estimate, has forcasted a very general "95%"(that too with 5% margin error) of the average rainfall. No setting time mentioned, no regional distribution of rain stated and no explanation of any parameter pertaining to the statement given by IMD. So any one region in the country can have rainfall as low as 85% and another region can have 110%, and still the estimate given will be correct !! And IMD states it will issue the exact update in June, after the monsoon has set in !!

International meteorologist Jim Andrews, and The International Research Institute (IRI) have observed that weak `El Nino` has clearly given way to a `Neutral` setting with respect to the middle and eastern Equatorial Pacific Ocean (ENSO); indeed, weak `La Nina` may be the next step. It is common meteorology understanding that `Neutral` to `La Nina` favors normal to above-normal rains for the SW Monsoon over India.IRI has maintained its outlook for an above normal rainfall in India this year.This in contrast to the below normal put by IMD.

IMD fails to give a regional distribution, but IRI has predicted heavy rainfall for the west coast and Saurastra.The monsoon current,will be supported by an expected evolving La Nina event in July, when good rains are expected.This is very crucial information from the point of view of kharif crops !

Thus international models predict an better organised and evenly distributed rainfall, with heavy falls along the west, specially during July/August. and an early onset.

Saturday, April 21, 2007

Hailstorm in Kuwait

Kuwait, one of the driest countries in the world, is still recovering from an astonishing bout of torrential rain, squally winds and giant hailstones which battered this desert state in recent days. Twice as much rain fell on Wednesday than the average level for the whole of the year. The rainfall totals were remarkable and probably unprecedented, with Kuwait airport reporting 302mm and Kuwait City 258mm of rain in 30 hours up to 9am local time on Thursday.

Weather experts said cold air from central Europe had encountered very warm, moist air from the Gulf. This, combined with a slow-moving area of low pressure, had fuelled explosive cloud development and the subsequent storms. Children squealed with delight as they collected and swallowed the pebble-sized hailstones. The hailstorm fascinated people in Kuwait, as many had not witnessed such a phenomenon before.

The high aloft has prevented this W.D. from moving into the sub-continent. It has gone far north and as of now almost dissolved. Thus the prevelent pre monsoon low is as such not "damaged" by this strong W.D. which , could have moved into India, if conditions were similar to that of last year.

Friday, April 20, 2007

Monsoon Watch -5

The IMD has issued its April Monsoon estimate for 2007.It has declared that the Monsoon 2007 will be 95% (+/- 5%) of the normal.

As it is an overall estimate of the all India monsoon,the break-up area wise needs to be seen.

The current heat wave has been pushed to the north west of India (map), and temperatures even in Pakistan have come down marginally.The highest today was compartively "low" at 43° in Pakistan (Nawabshah) and 42° in India (Jodhpur).(These figures seem lower after the heat wave, but are near normal levels). This is a temporary phase due to the thundershowers in the region, and the temperatures will rise back to the mid 40s.

Maharashtra and Gujarat are likely to heat up again from 22nd. and interior parts may touch 44°.Mumbai will be extermely uncomfortable,especially at night, with the humidity increasing,and the minimum likely to be 28°.No localised thundershowers are likely in Maharashtra till this month end.

The seasonal low is establishing over Northern parts of the sub continent,and thus assuring a favouarable pre monsoon condition.The Bay has heated up a bit,but needs to be observed in the next few days, before a low formation can be assured.

Thus, the "land part" is performing well,ahead of schedule (for the monsoon),with the trough in the southern peninsula intact.While the "sea part" (the bay branch & arabian sea branch) is not heating up enough to form the pre monsoon low as needed.But I estimate the seas will heat up next week, and it seems the arabian sea is heating up faster than the bay.

Infact, my personal estimate is the monsoon should set in a few days before the due date.

Tuesday, April 17, 2007

Monsoon Watch -4

The non development I observe from my last writing is that the Bay is not heating up as required.The sea temperature in the bay is still around 30°,or maybe even 29°c. This has surely prevented the low from forming in the bay,as anticipated. In fact, the low last week off Sri Lanka coast did not move at all, and just persisted as an UAC.Actually, the bay sea temperature is 1 -1.5° below normal. As a result,I do not see any "pre monsoon low" forming in the bay in the next 8 days at least.

The sub continent land mass heating continues,and as mentioned the highest temperatures have touched 45°,in DGKhan(Pakistan) and Ganganagar.The formation of the seasonal low over the sub continent is on schedule,and the trough formed in the southern parts of the peninsula has triggered off the pre monsoon thundershowers in Maharashtra,Karnatak and Kerala.

With the humidity in Mumbai set to gradually increase,the weather is sure to get uncomfortable in the coming weeks, and as for the rest of Maharashtra, stray convective thundershowers will continue. Gujarat should become increasingly hot in the remaining days of April.

Thursday, April 12, 2007

Monsoon Watch - 3

The low pressure that formed around the southern tip of India, suddenly weakened into an "upper air circulation"(UAC). Some models suggest that this UAC may shift north east and head into the Bay of Bengal.If the Bay temperatures rise,(still around 30°), this may get converted into a low.

But, on the positive side for the monsoon,a "wind discontinuity line" has established along a north-south alignment in the southern peninsula. It could evolve into a trough of low pressure.This north - south trough gets converted to an east - west trough, before the on-set of the monsoon.
The line of wind discontinuity today runs from the southern tip of india upto Nagpur.The eastern side has moist south easterlies,thus producing convective rains,and the western side has dry northerlies.Thus, thunderstorms develop along the line of wind discontinuity.This is a convential pre monsoon feature.

With the confirmed deflection of W.D.'s away from the northern regions now,the ground for further heating of large areas of the sub continent has been prepared.Within a few days,temperatures in Sindh (Pakistan),Gujarat,Rajasthan may go upto 44°-46°.

In the Southern Hemisphere, the cyclone activity has stopped since the first week of April. At the instant, the south easterlies down there are re-curving at around 5°s, and thus indicating that the ITCZ is around 5°s. While the south easterlies should to gain speed in about 15 days, the ICTZ can cross the equator around first week of May, that is per the normal date. Once the moves towards the north, monsoon lows are formed in the Bay and Arabian Sea branch.

As on today, the monsoon seems to be on schedule.

Sunday, April 08, 2007

Snowy Easter in Moscow & Washington.

Very interesting weather on Easter weekend.
Extremely heavy snowfall and unusually low temperatures affected Russia yesterday, as Muscovites celebrated the Easter period. Meteorologists say that this is the heaviest Easter snowfall in Moscow for many years. One tourist said it was normally warm at this time of year ‘but now it is very cold on the eve of Easter.’The Maximum temperature was 5°c and the minimum 0°c on Saturday.

In Washington D.C. visitors to the capital awoke to see cherry blossoms coated with snow on Saturday.The high here was 4°c and the low -1°c on Saturday.

Also, for the record,unusual snowy weather also occurred in North Texas as light snow flurries fell on Saturday morning. The last time spring snow fell here was April 1938, according to the National Weather Service (NWS) records. On Saturday the maximum temperature in Amarillo was -2C (28F) when the long-term average is 21C (70F).

Saturday, April 07, 2007

Monsoon Watch - 2

Carrying on from the last Monsoon Watch, it is seen that no W.D.'s have penetrated into the Northern India region. The heat wave has extended into South Rajasthan and Gujarat region now.With increase in day temperatures heat wave conditions likely to extend into rest of Maharashtra and West Madhya Pradesh,.The heat has also crossed the border into Pakistan today,with Chhor,in Sindh recording 44°. Akola was also at 44° today,and a number of places in Gujarat and Maharshtra were in excess of 41°.

So, as mentioned in the previous "Monsoon Watch"(MW), this heat wave will induce a "seasonal low" in the Northern parts of India(later to extend into Pakistan), around the middle of April, as it is properly getting induced by the pre monsoon heating.There are no indications of the heat subsiding, to a large extent, in the next 10 days.

Also, in the Bay,a trough of low has formed east off the Sri Lanka coast.This is likely to develop into the predicted" low" in the bay by around the 15th.of April,( as the bay waters have started heating up now).Though the bay has not heated enough yet, the south bay is still at 30°, it should start warming up fast now.This will be the first pre monsoon "low" of this season in the bay, and with this ,the pre monsoon features will set in.

These developments are as anticipated in "MW" 1, so, if maintained,we will then observe the change in the cross equitorial wind pattern and the tropical jet straem in the next 15 days.

As on now,the Monsoon Calendar seems to be about a week ahead of the normal date.

Tuesday, April 03, 2007

A moderate W.D. from the Arabian land has caused thunder storms in Dubai.Heavy rains accompanied by thunderstorm and lightning disrupted life in parts of Dubai and Sharjah on 2nd.and 3rd.
Poor visibility and waterlogging on roads caused several accidents with Dubai alone reporting 30 minor accidents.
Strong winds brought heavy showers on Monday afternoon in Dubai and the Northern Emirates .Sharjah experienced abrupt and heavy showers at approximately 2.45 pm, which was accompanied by strong winds and managed to knock down several trees near residents' homes.

Now, normally, in winter, this system would have moved into India.But due to the high temperatures,and the blocking ridge of high pressure,the W.D. is moving northwards into Afghanistan and N.Pakistan causing much damage there..
Avalanches are causing much damage a result of continuous heavy rain falling over the Kush Mountains which were covered in deep snow. As much as 1.83 metres (6 feet) of snow has fallen over the past several days, and heavy rains have also caused landslides in the vicinity.

This is the result, as mentioned in my previous blog, of the W.D. getting shunted North, and creating the ideal pre monsoon scene for the sub continent.

Sunday, April 01, 2007

Monsoon Watch - 1

Heat wave conditions continued to prevail over some parts of Rajasthan, West Madhya Pradesh and adjoining north Maharashtra. They have also developed over some parts of Haryana, Delhi and East Uttar Pradesh. The day temperatures are 5-6 °C above normal over this region.
This heat wave bodes well for the orderly tranformation of weather into the "pre monsoon" stage soon.
Any prolonged cooling of the north, like last year ,would have been a cause for delay in the monsoon.The heating of the plains, now, is a must for the Low Pressure to build up in the next 15 days.This seasonal low in mid April will be induced by the pre monsoon heating of North Pakistan and Rajasthan.
With the W.D. now having been shunted North and getting spent out, a second major heat wave could be expected in the second week of April,and the mecury will peak to levels of 4-6° above normal.

On the Bay side, normally,the month of April witnesses about 2'' low's'' developing (these may even become cyclones like the one last year). A warming Bay of Bengal may detect the first ''Low'' around the 15th.This too is a pre monsoon feature.

If these developments move as per schedule,with a'' low'' in the Bay forming in the middle of the month,the wind pattern across the equator may change faster than expected,and we may see the monsoon, forecasted today maybe, a week early.

We follow up with a next review after 5 days and observe the progress.