Monsoon is getting erratic, just
when the peninsula was preparing for heat waves, there is rush of rains –intense,
short with high winds. What used to be stretched out nimbostratus affair –
steady moderate redolent dreamy rain, rarely any thunderstorm or high
winds -that was mostly confined to NW monsoon, is now overtaken by cumulonimbus intermittent intense dreadful show. It is
ofcourse respite from heat for millions of people but along the Western Ghats
rains are getting erratic and sinister. Warming Arabian ocean –sea surface
temperature, increases moisture in the atmosphere enhancing convective updraft
for cumulonimbus and with warm air holding more moisture (7% more with 1degree centigrade
warming) hence the intensity of short lived rainfall. Convective storms are
brief and swift as it releases energy rapidly through burst of rain and
downdrafts as heavy winds -normally wind hovered around 40-50km/hr but now it
is mostly 60km/hr and more. Hills of Western Ghats also create localized intense
orographic rains –sometimes cloud bursts, in the fragile landslide prone region.
This time around monsoon not only landed on Kerala coast much early but advanced rapidly, accelerating monsoon onset and northern progression. Other global factors like Mascarene high intensification, Somali jet strengthening, favorable MJ oscillation, absence of El Niño, reduced snow cover, so on increase moisture for changing pattern of south west monsoon rains.
