South India Wetting Up

--South Asia:

An ongoing weather story is the on dealing with the North East Monsoon and the long "swoon" in rain over southern India this month. The lengthy break in the rain that began in late October has left some areas (of which greater Chennai is one) short on rain at the heart of the vital, short rainy season.

The last few days have seen some heavy falls of rain over southern India (mostly Tamil Nadu) and Sri Lanka:

Tamil Nadu:

Cuddalore...8.7 inches/22.1 cm

Karaikal...7.2 inches/18.3 cm

Tiruchchirappalli...5.2 inches/13.2 cm

Chennai...3.8 inches/9.6 cm

Sri Lanka:
Trincomalee...6.3 inches/16.0 cm (within 24 hours as of 0600 UTC Monday)

The rain in Chennai has accounted for most of the month's sparing (thus far, anyways) rainfall.

What is happening as of Monday is that broad, weak low pressure has settled over the southwestern Bay Bengal and Sri Lanka. In the process, rains of the Inter Tropical Convergence have been directed ashore in the aforesaid areas.

Broad, weak low pressure (not a well-marked depression or cyclone) will shift slowly westward over Sri Lanka and southern India to the southeast Arabian Sea during the next several days triggering widespread rain over southern India (mostly south of 15 degrees North latitude) and Sri Lanka. There will be heavy falls and local flooding may be a substantial problem.

--What about a tropical cyclone? Well, I am beginning to think the one is in the works come the end of the week. The GFS has been consistently showing a well-marked low over the southern Bay of Bengal as of Saturday and Sunday. Something to follow carefully.

--Another thing that could happen is that moisture linked to the broad tropical low will seep northward over peninsular India, maybe culminating in hit-or-miss thunderstorms along the heights above Mumbai. This would be an unusual time for such weather, but temperature has already been unusual (hot daytimes) over Mumbai and other sites of western India thus far this month.

--South West Asia:

A broad upper trough is forecast to dip southward over the Mideast Gulf during this mid to late week. In answer, there will be potential, by early Thursday, for a few showers and thunderstorms in the area of UAE, far-northern Oman and southern Iran. It is this same broad upper trough that will be helping the aforesaid tropical weather to unfold over the southern Subcontinent.

--South America:

Though it surely will, it seems as though the heat will never break in far-northeastern Brasil where the states of Maranhao and Piaui have been baking for weeks. Something like 8 or 10 straight days of 100 degrees F/38 degrees C at Teresina, Piaui.

--Easterly wind flow against the Serra do Mar (Atlantic Highlands) of Santa Catarina triggered local rainfall to 20 inches/50 cm late last week. And a setting not unlike this has been happening northeast of Rio de Janeiro. In Espirito Santo, Vitoria has had 9.2 inches/23.4 cm of rain within about three days.

--Last week was a hot one over much of Argentina with 40-degree heat southward into northeastern Patagonia (San Antonio Oeste, eastern Rio Negro). Sunday, Catamarca, in the dry northwest, hit 41.5 degrees (107 F).

As of Monday, the southern spring heat wave has triggered a few strong thunderstorms over the northern half of Argentina. And it looks like more heat on the way this week including hit-or-miss thunderstorms through Wednesday. A cold front from the southwest could trigger a few severe thunderstorms as it cuts into a heat wave over northern and middle Argentina beginning at mid week.


Source: accuweather.com