The utilities of the Doppler Weather Radar (DWR) products.

DWR gives various products all in the form of images. Out of them only six are displayed in IMD website. This is because of want ‘internet space’. The displayed products are PPI(Z) close range, PPI(Z), PPI(V), MAX (Z), SRI, PAC.

PPI means plan position indicator, MAX(Z) means display showing clouds of maximum reflectivity, SRI means surface rainfall intensity, PAC means precipitation accumulation.

PPI(Z)-close range and PPI(Z) are same type of picture. The first one is showing only 150 kms. And the second one is showing 500 kms. When they are displayed with the map in the background, the PPI(Z) close range will show more detail – ie. near the city where exactly the cloud is there. The  intensity of the echoes is as per colour code.

MAX(Z) is also providing almost the same information as PPI(Z) is giving. Here the additional information is the height of the cloud displayed in 3D method. Here there can be an element of doubt. Imagine a situation where line squalls are seen as + (plus sign), here the cloud will be seen a single peak. Also depending upon the intensity range that we have chosen it will show multiple colour. If you closely look at the picture there will be a slight variation in the intensity range of the PPI(Z) and MAX(Z) pictures.

SRI picture gives information only about rainfall. Here the colour indicates the intensity of rainfall.

Now if you want to give a forecast for rainfall, thunder, wind squall, then you have to watch the radar pictures continuously from the formation of cloud. Preferably from the formation of a cloud, as seen in the DWR we should put the pictures in a loop. This will give us information about intensity (to forecast thunder), movement (to issue location specific and time specific forecast), the hail signature in the MAX(Z) product and how much rainfall is expected from SRI product.