-Marking the Days
With the approach of June, sights in the Indian subcontinent have without a doubt been turning to the coming rains of the South West Monsoon.
Weary from weeks of dusty, sweltering heat, more than a billion people will hope for life-giving rain and a break from daytimes reaching 40 degrees to sometimes 45 degrees (104 to 113 degrees F).
The latest tropical cyclone, Mahasen, has been a harbinger of the coming seasonal flip in wind patterns that will breed widespread cloud and rain, beginning in the south and east of the subcontinent.
Image credit: India Meteorological Department.
The southwest Indian state of Kerala, a bellwether for the onset of the South West Monsoon and the subject of a statistical model forecast by forecasters in India, normally witnesses the onset of the rain-giving phenomenon near the start of June. Within four to six weeks thereafter, the leading edge of the mega weather system would have spread throughout India, Bangladesh and Nepal to gain a foothold inside Pakistan.
Tropical Cyclone Mahasen has necessarily had some say in the onset timing of the Monsoon. As the India Meteorological Dept. (IMD) indicated in its website on May 15, the cyclone was instrumental in initiating a cross-equatorial flow in the lower atmosphere of the Andaman Sea and the nearby Bay of Bengal. It is cross-equatorial wind flow across the breadth of the Indian Ocean that is at the wheelhouse of South West Monsoon.
Based on the shifts over the eastern Indian Ocean, the IMD have stated, as of May 17, that the South West Monsoon has advanced to parts of the Andaman Sea and southern Bay of Bengal. However, the IMD also say that the onset timing in this part of the Indian Ocean basin has little predictive power with respect to monsoon advance and rainfall in India.
-Forecast for the Monsoon onset in Kerala state
Results of the IMD's statical model forecast point to a June 3 onset, give or take four days, of the 2013 South West Monsoon in the state of Kerala. Onset here was on June 5, 2012, but on May 23, 2009, the earliest onset for the period 2005-12.
In the meantime, going forward for the next one to two weeks, much of the subcontinent will continue to suffer stifling heat, topping 45 degrees C (113 F) in many instances. During this period, the worst of the heat will tend to shift northward and westward, settling over the Indus River plains and the Thar Desert before the end of May.
Thursday, readings hit the 45-degree-C heatwave benchmark in a few locations of India with southern Pakistan waxing hotter still. In India, Nagpur reached 45.4 degrees C (114 F), whereas Jaisalmer and Ramagundam hit 45 degrees C (113 F). All were at least marginally hotter on Friday.
In Pakistan, Nawabshah led the way Thursday, topping 47 degrees C (117 F). Right behind was Jacobabad, where 46.5 degrees C (116 F) was reached. Here again, Friday's reading were at least this high.
The plum rains are known as "meiyu" in China, the "baiyu" or "tsuyu" in Japan, and the "jangma" in the Koreas. The heart of the plum rain season stretches from early June to mid-July, with a tendency to shift south to north across the affected area.
In the wake of the mid-June cloudbursts, most of Pakistan to northwestern India last week saw a return to dry, hot weather typical of the weeks leading up to the Monsoon onset. It was as if the Monsoon withdrew to its "normal" position for the latter half of June.
The 38.5 degree C (101 degrees F) reading Tuesday in Ajaccio, Corsica, may have been tops in Europe.
Monsoon Onset was June 13th, 2013, in Delhi, almost two weeks earlier than average. The June 15th onset at Karachi and Islamabad was more like three week ahead of schedule.
In Pakistan, hit-or-miss downpours missed the Sindh capital, Karachi. One did hit Pad Idan, where it left 60 mm of rain Wednesday. This was more than 20 times greater than the normal June rainfall.
It is still possible that this scenario is over wrought as to the intensity and spread of rain in Pakistan and northwestern India. However, it is the hunch of the present forecaster that some very unusual weather is going to unfold in the Subcontinent during the next week!