The Summer Monsoon looks set to gain a foothold on the Indian Subcontinent within as little as a few days. Monsoon onset would open the summer rainy season, beginning in southern and eastern parts of the Subcontinent. The Monsoon normally advances quickly into northern and western India during the first half of June before finally reaching most of Pakistan by mid-July.
The India Meteorological Department (IMD) tracks the Monsoon advance, beginning in May, then follows its withdrawal from the Subcontinent late in the summer. The IMD have forecast an onset date of June 3 in the southwestern India state of Kerala. Normal onset date here is about June 1.
Infrared satellite image taken 1700 UTC Thursday, May 30, 2013, showing "pre-Monsoon" rain clouds over southern and eastern India as well as Bangladesh. At this time, the leading edge of the northward-advancing Monsoon was stretched southwest to northeast over the Bay of Bengal. (credit: India Meteorological Dept.)
As of Thursday, May 30, the leading edge of the Indian Monsoon stretched over the Bay of Bengal, from east of Sri Lanka northeast to about Akyab, Mynamar, according to the IMD. However, "pre-monsoon" rain was already falling in parts of southern and northeastern India as well as Bangladesh. A two-day soaker left nearly 5 inches of rain at Jamshedpur, in the state of Jharkhand.
Numerical forecast models available to AccuWeather.com on Thursday showed continued northward spread of the environment favorable for rain and thunderstorms. However, it was not clear which day would be the one most likely to be declared the opening day of the Summer Monsoon in India by the IMD.
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!