premonsoon season

WHAT ABOUT THE PRE-Monsoonal Activity???

After looking at the forecast for cyclone in may, many will ask me about the premonsoonal activity.

The premonsoonal activity likely to take a sharp turn from April 23rd and fetch some good showers to Kerala, Interior Tamilnadu, Parts of South-interior Karnataka. As the Line of Wind discontinuity (LWD) moves inland of south india, rainfall will occur during evening times with loud thunder and even hail at some places.

This time the Premonsoonal rainfall seems less over south-eastern india and adjoining areas of andhra pradesh, Telangana.
Moist winds from Arabian sea enter the inland viz. Kerala, Coastal karnataka and finally enter the interior parts of south india. The sun heats up the inland and causes the upward motion of air molecules, which is referred as instability of the atmosphere. The cloud popups will be forming and cause some rain spell, depending on wind-shear, adiabatic lapse rate, Moisture, Convergence at lower levels, Cape and wind-flow.
I am expecting a Start of thunderstorm season, when the wind-flow over kerala persist moisture. I see some similar conditions from 22nd april. Adding a day, tamilnadu will get some rains from 23rd april. Meanwhile heat will persist over andhra and telangana with some intermediate showers.

CFS-ENSEMBLE FORECAST

Monsoon likely to be Above Normal over india with +103% LPA:

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May forecast

Latest CPCC, Dynamic Models telling a delay in Monsoon Onset:

The madden julian Oscillation(MJO), Arctic Oscillation are the Season changers of the most of places around world. Mainly, in india the MJO plays a crucial role in increasing/reducing of rainfall.

Madden Julian oscillation (phase1-4) makes a constructive superimposition with elnino/lanina generated Sea-surface temperature in indian ocean and makes a wet phase in west coast of india. Monsoonal winds will gather good momentum and contain heavy moisture during favourable MJO phase.

When MJO moves to indonesia, the Outgoing Longitudinal Radiation becomes warm and indicates destructive interference with elnino/lanina, which often reduces the rains over india and ultimate weakens the monsoon jet. Thus the Anti-cyclone over tibet breaks and the monsoon forms a break period. MJO phase lasts for 30-90 days. Out of which half of days corresponds to increased convection and remaining half corresponds to decreased convection.

May Month conditions:

The MJO likely to move into phase 2 around May-last week. The convective Heat in MJO, likely to supply heat to tropical cyclone and enhance Tropical cyclone Heat potential. The total heat energy adiabatically transfers from MJO-OLR to the atmosphere. Molecules make a rapid collision and result in relative vorticity between layers. The warm air raises upwards and cool rapidly and the energy makes the cyclone to gain mass and velocity, which corresponds to Momentum. As the Momentum increases, the heat continues to move into the system in a rapid pattern and make the system highly adiabatic. MJO makes the interference pattern and cause vigorous convection. The vortcity increases exponentially with TCHP. As the latitude ascent increases, the coriolis torque corresponds to Moment of inertia around the center of storm and drives the cloud band with the heat equal to 140-200 kj/cm^2. The cold band gets wrapped by warm air, which corresponds to inflow and outflow of the storm. Rain band will popup around the eye at a distance of (xd/2). As the distance increases the amount of rainband and TPW(Total precipitable water) increases and then suddenly falls to minimum where (dx/dr =0)--x is the axial distance from the cyclone and r is the radial distance of storm.

The May cyclone may form around maldivies as a circulation and move north wards and get intensified as a cyclone in the mid-way and finally weakens and touch pakistan coast around May 31---as per latest forecast trends.

BY

B.Sai praneeth

(Weather of south india)

Last Year Chapala cyclone precipitation