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Jan 13, 2016

IMD changes language in weather forecasting and redefines terms

1/13/2016
IMD changes language in weather forecasting and redefines terms
The India Meteorological Department (IMD) has changed the languages and also re-defined terms that are not scientifically precise in weather forecasting.
In this regard, IMD has issued official notification to do away with outdated language to avoid communication gap with the civil administration so they can be more realistic in case of upcoming weather events.
IMD has reviewed the terminology and factors determining each of these terms based on supporting observational data.


Following are the changes

Classification all-India rainfall into five categories
  • Normal: ± 10 percent of the long period average (lpa).
  • Below normal: Rainfall lower than 10 percent below average of the lpa.
  • Above normal: Rainfall greater than 10 percent above average of the lpa.
  • Deficient year: Rainfall deficit between 10 and 20 percent up to 40 percent of India’s spatial area.
  • Large deficient year: Rainfall deficit of over 10 percent across more than 40 percent of India’s area.
IMD New standardized key terms
  • Heat wave: Temperatures greater than 4.5 Degrees Celsius above usual temperatures for the region.
  • Severe heat wave: Temperatures greater than or equal to 47 Degrees Celsius.
  • Cold wave: Temperatures less than 4.5 Degrees Celsius below usual temperatures for the region.
  • Severe cold wave: Minimum temperature is 2 Degrees Celsius or lower.
Criteria to classify seasonal rainfall
  • The rules have been changed to classify seasonal rainfall. IMD has introduced 6 new categories replacing old four rainfall categories (excess, normal, deficient and scanty). New categories are
  • Large excess: 60 per cent and above.
  • Excess: between 20 per cent and 59 per cent.
  • Normal: minus 19 per cent to plus 19 per cent;
  • Deficient: minus 20 per cent to minus 59 per cent.
  • Large deficient: below 60 per cent
  • No Rain: 0 per cent.

Nov 4, 2015

Tropical Cyclone Chapala hits Yemen triggering heavy floods

11/04/2015
A rare tropical Cyclone Chapala has slammed into Yemen triggering heavy flooding and causing damage in coastal region of the war racked country.
The cyclone made landfall in the south eastern provinces of Hadramawt and Shabwa along the Gulf of Aden coast of Yemen in Arabian Sea bringing winds of speed more than 100 kms per hour.
 
facts
  • Indian Meteorological Department (IMD) has categorized Cyclone Chapala as a Category 4 equivalent storm on the Saffir-Simpson Hurricane Wind Scale.
  • It is believed that Cyclone Chapala is the most powerful storm that has hit Yemen in last five decades.
  • It is the second-strongest cyclone on record over the Arabian Sea, only after Cylone Gonu (2007).
  • The rainfall brought by cyclone has caused flooding of rivers which are usually dry causing destructive mudslides.
  • Earlier the cyclone had wreaked havoc on the island of Socotra, located 350 kilometers off the Yemeni mainland.
Cyclone Chapala was formed after a low pressure was formed over the Arabian Sea with deep depression intensity. The low pressure was formed due to record warm water believed to be associated with an El Niño event and low vertical wind shear.
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