July outlook for South Asia's monsoon
By
Jason Nicholls, AccuWeather senior meteorologist
Updated Jul 4, 2021 1:01 PM EDT
After a fairly good start to the monsoon across India and even a monsoon low earlier in June, the monsoon entered a break period around mid-June. This resulted in the monsoon advance stalling to the east of Delhi, Punjab and Haryana over the past three weeks.
Despite the weakening of the monsoon circulation during the second half of June, cumulative rainfall for the month across all of India was +10% of normal. Areas of northwest India where the monsoon has yet to officially arrive even had near- to above-normal rainfall owing mostly to pre-monsoon rainfall from western disturbances. The driest areas were in western Gujarat, parts of Andhra Pradesh and parts of northeast India. As the break period carried into early July and rising to normal in many areas it brought cumulative rainfall for all of India down to +1% of normal as of 4 July.
The main driver that brought about the break period in India's southwest monsoon is the emergence of the Madden-Julian Oscillation (MJO) into phase 1 around 12 June. The MJO then remained stalled in phase 1 until finally drifting into phase 2 toward the end of June. Several papers have noted that the MJO in phases 7, 8, 1 and 2 resulted in a break period in India's monsoon with a maximum in the weakening of the monsoon occurring in phase 1. Phases 3-6 of the MJO tend to result in a strengthening or active period in the monsoon. A weak MJO or MJO returning to the origin circle also tends to be beneficial for monsoon rainfall across India.
As the previous graphic shows, most modeling favors a weak MJO or the MJO moving through the more favorable phases 3-6 starting later this week. This change in the MJO should result in the monsoon advancing into Delhi and possibly through the remainder of India late in the week or next weekend.
In addition to the MJO finally turning more favorable, other conditions are expected to turn more favorable for rainfall across India and Pakistan, especially in northwest India and Pakistan, from the week of 11 July through much of the rest of July. The CFS forecast and the India Meteorological Department's extended range model guidance both support the idea of better rainfall across much of India starting the week of 11 July.
Conditions may even become conducive enough for a monsoon low to develop in the Bay of Bengal off the Andhra Pradesh, Tamil Nadu or Odisha coast around 11 July. The general steering flow should guide any monsoon low northwestward or west-northwestward toward Maharashtra or Madhya Pradesh early the week of 11 July. Enhanced rainfall and areas of flooding are possible along the track of any monsoon low that happens to form.
The more optimistic outlook for a wetter pattern in India and Pakistan later in July should result in July rainfall averaging close to normal across India and Pakistan as a whole. Parts of western Rajasthan and northeast India into Nepal as well as around Delhi could average drier than normal for July. Meanwhile, portions of Jammu and Kashmir into northern Pakistan, as well as parts of central India could average wetter than normal. We are also expected near- to perhaps slightly above-normal rainfall across Sri Lanka during the month of July.
Stay tuned to AccuWeather.com for updates on the weather across India, Pakistan, Nepal and Sri Lanka or follow me on Twitter @jnmet.
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Weather Blogs / Global weather
July outlook for South Asia's monsoon
By Jason Nicholls, AccuWeather senior meteorologist
Updated Jul 4, 2021 1:01 PM EDT
After a fairly good start to the monsoon across India and even a monsoon low earlier in June, the monsoon entered a break period around mid-June. This resulted in the monsoon advance stalling to the east of Delhi, Punjab and Haryana over the past three weeks.
Courtesy IMD
Despite the weakening of the monsoon circulation during the second half of June, cumulative rainfall for the month across all of India was +10% of normal. Areas of northwest India where the monsoon has yet to officially arrive even had near- to above-normal rainfall owing mostly to pre-monsoon rainfall from western disturbances. The driest areas were in western Gujarat, parts of Andhra Pradesh and parts of northeast India. As the break period carried into early July and rising to normal in many areas it brought cumulative rainfall for all of India down to +1% of normal as of 4 July.
Courtesy IMD
The main driver that brought about the break period in India's southwest monsoon is the emergence of the Madden-Julian Oscillation (MJO) into phase 1 around 12 June. The MJO then remained stalled in phase 1 until finally drifting into phase 2 toward the end of June. Several papers have noted that the MJO in phases 7, 8, 1 and 2 resulted in a break period in India's monsoon with a maximum in the weakening of the monsoon occurring in phase 1. Phases 3-6 of the MJO tend to result in a strengthening or active period in the monsoon. A weak MJO or MJO returning to the origin circle also tends to be beneficial for monsoon rainfall across India.
As the previous graphic shows, most modeling favors a weak MJO or the MJO moving through the more favorable phases 3-6 starting later this week. This change in the MJO should result in the monsoon advancing into Delhi and possibly through the remainder of India late in the week or next weekend.
In addition to the MJO finally turning more favorable, other conditions are expected to turn more favorable for rainfall across India and Pakistan, especially in northwest India and Pakistan, from the week of 11 July through much of the rest of July. The CFS forecast and the India Meteorological Department's extended range model guidance both support the idea of better rainfall across much of India starting the week of 11 July.
Courtesy IMD
Conditions may even become conducive enough for a monsoon low to develop in the Bay of Bengal off the Andhra Pradesh, Tamil Nadu or Odisha coast around 11 July. The general steering flow should guide any monsoon low northwestward or west-northwestward toward Maharashtra or Madhya Pradesh early the week of 11 July. Enhanced rainfall and areas of flooding are possible along the track of any monsoon low that happens to form.
The more optimistic outlook for a wetter pattern in India and Pakistan later in July should result in July rainfall averaging close to normal across India and Pakistan as a whole. Parts of western Rajasthan and northeast India into Nepal as well as around Delhi could average drier than normal for July. Meanwhile, portions of Jammu and Kashmir into northern Pakistan, as well as parts of central India could average wetter than normal. We are also expected near- to perhaps slightly above-normal rainfall across Sri Lanka during the month of July.
Stay tuned to AccuWeather.com for updates on the weather across India, Pakistan, Nepal and Sri Lanka or follow me on Twitter @jnmet.
Report a Typo