Thursday, August 11, 2011

Can convective activity be termed as monsoon rain

Many a times it is given to note that during SWM period the cause of rain in Tamilnadu is referred to as convective. It is convective activity due to warm air advection during these rainy days. Most of the time Warm Air Advection [WAA] is inferred from radar products. Moist warm air from WEST after crossing western ghat gives rainfall from WEST to EAST in Tamilnadu. To day [11.08.2011 / 2200 hrs IST] it is evident from satellite imagery and DWR products that moist air is advecting and it may rain at S-SW /NW parts of Villupuram & Puducherry to night.


  1. Anonymous10:53 PM

    It started raining in south of Chengelpet, Maduranthagam areas now

  2. whatever it is rains over TamilNadu is like Nectar falling from havean!!!
    State where out of 5 years 3-4 years will be drought rains are divine blessings.

  3. But statistics show TN has been receiving either Normal or Excess rainfall for the past 10 years. Moreover, TN is one of the few states which receive rainfall for most part of the year (Though not heavy and steady). South and South eastern part of TN are the ones which receive less rainfall during SWM. North, Central, Western, NW and NE all receive good rainfall even during SWM.

  4. Anonymous12:35 AM

    As on date [13.08.2011] TN & PDY sub division received an actual rainfall of 128.2mm against NORMAL rainfall of 146.4mm for the period 01.06.2011 to 13.08.2011 which is [-]12%. In IMD term [-]19 to [+]19 percentage is considered as normal. (How and why I do not know. The rainfall during this period can definitely be termed as SWM rainfall, since rain bringing clouds will be moving from W to E.
    During any SWM period TN & PDY rainfall average will be between 36.2 cm to 42.0 cm. [Courtesy:UKMET, & IITM Pune]
    Except to south eastern most coastal regions -like Thoothukudi & parts of Tirunelveli & parts of Kanyakumari districts- rainfall distribution at any given week during SWM will be ISOLATED to occasional FAIRLY WIDE-SPREADS. One can infer it from daily rainfall graph uploaded in the web. So the convective action bringing rainfall during June to Sept may be termed as SWM rainfall, even though TN is considered to be in the rain shadow region.