AMOUNTS 20 OR MORE TIMES NORMAL MARCH RAINFALL
A rash of heavy falls of rain that began at the middle of last week has continued into Thursday, the last day of March. Going through the AccuWeather.com database, I find that rainfall has topped 50 inches (127 cm) at Nakhon Si Thammarat, on the eastern side of the Malay Peninsula. Normal monthly rainfall here is about 2 inches, or 5 cm.
It is also typically a hot time of the year, the Inter Tropical Convergence being normally located to the south. Yet the heavier falls of rain have coincided with daytime temperatures 10 to 20 degrees F (5 to 9 degrees C) below normal.
Another site in the area, the island of Ko Lanta, has had nearly 44 inches (111 cm) of rain within seven to eight days. I believe that normal monthly rainfall here is less than that of Nakhon Si Thammarat.
Google Maps Image.
The results have been tragic, with a number of people killed or missing. A mudslide in the province of Krabi seems to lie behind an ongoing news story even as I write.
The spark for these rains is not obvious to me. There has been no major pressure center, maybe no more than a relatively weak tropical wave that stalled in its westward drift from the South China Sea.
At least one pulse of the North East Monsoon (relatively dry and cool) did cut into the area from South East Asia; this would help to account for the unusual "chill."
Although unusually high sea surface temperature is often correlated with high tropical rainfall, readings of seas eastward from the Malay Peninsula have lately been below normal.
The worst seems to be over, yet numerical models indicated that there will be at least scattered rains daily, even heavy downpours.
QUEENSLAND CLOUDBURSTS, YET AGAIN
In the area of the coastal towns of Mackay and Bowen, rain has fallen in buckets lately. Within the three to four days ending Thursday, March 31, rainfall of 12 to 24 inches (30 to 60 cm) has been registered, according to the Australian Bureau of Meteorology. At the top end of this range was a site called Proserpine.
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!