TROPICAL LOW PRESSURE IN THE MOZAMBIQUE CHANNEL
Tropical low pressure has formed in the Mozambique Channel, where it could become an important tropical cyclone before potentially crossing the shores of western Madagascar Sunday or Monday.
Already, as of Saturday, locally heavy rain has pelted both sides of the channel, mostly in the northern halves of Madagascar and Mozambique, this week. Likewise, the Comoros Islands have been dosed.
Tropical Low Pressure in the Mozambique Channel as of 1700 GMT Saturday, Jan 7, 2012 (Navy Research Lab Monterrey)
Satellite imagery on Saturday has shown deep convective rains reaching well northwest into Africa, likely along the southern edge of the regional Monsoon. This stream seems to have been feeding the gathering low.
On Friday, the Joint Typhoon Warning Center (JTWC) plotted the center of low pressure within 50 to 100 miles of central Mozambique. Now, as of Saturday afternoon, local time, the low's center seems to be over the middle of the southern Mozambique Channel, drifting southeastward.
FLASH FLOODING GREATEST HAZARD
Landfall in Madagascar looks set to happen near, if not between, Morombe and Morondava, Madagascar.
A slower forward speed could favor a stronger storm, as sea surface temperature in the likely path of this low is about 29 degrees C as of early Friday.
Barring explosive deepening to a storm of hurricane intensity, the greatest hazard stemming from this tropical weather system will be that of flash flooding. I believe that western Madagascar north the low's path, together with southeastern Madagascar, will be at greatest risk of excessive rain and serious flooding through the middle of next week.
Historically, Madagascar has suffered serious flash flooding during its summer rainy season, especially in the drier, scrubby western side of this huge island. A rough estimate is that highest falls of rain will be between 8 and 16 inches (200 and 400 mm) through the first half of the week.
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!