Delhi is fog free from last 5 days, which is attributed to north-westerly winds which is not allowing the formation of fog after the passage of the western disturbance.
Forecast based on ensemble model prediction of IITM and IMD-GFS
On 17 January there is a 60% probability of moderate fog in Delhi, some places especially Delhi airport can record visibility in the range 200-300m (Figure 1).
As the next western disturbance, is going to arrive on 19 January, wind speed over Delhi will decrease significantly (Figure 2).
Another parameter which determines how conducive the atmosphere is for mixing is the ventilation index (Figure 3). Lower values of ventilation index indicate that the atmosphere is not favourable for pollutants to disperse thus more favourable for smog and fog. It can be seen from figure 3 that from 18 January onwards the ventilation index is forecasted to decrease and low ventilation index will persists in Delhi till 22 January. In addition, the planetary boundary layer’s wind speed is also forecasted to decrease from 18 January to 22 January.
Based on these factors chance of moderate fog in Delhi (visibility in range 200-300m) on 18 January and dense to very dense fog from 19-22 January (visibility less than 50m).
Fig 1. Ensemble probability forecast of fog for IGI Delhi. Source: IITM
Figure 2. wind forecast at 850 hPa by the IMD-GFS model for 17 Jan, 19 Jan and 20 Jan
Figure 3. Forecast of ventilation index and planetary boundary layer mean wind speed for Delhi during the period 17-25 January 2023. Source: IMD-GFS
Written by: Dr. Vineet Kumar Singh
Research Scientist, Typhoon Research Center, Jeju National University, South Korea
Bangalore cold...15th January
Bangalore recorded the lowest minimum temperature of 12.8 °c in the past 24 hours. The last time the city recorded the lowest minimum temperature was in January 2019....12.4°c
Coldest in Karnataka was Bagalkote at 8.6°c.
The lowest minimum temperature recorded in Bengaluru, according to IMD data was 7.8 degrees Celsius on January 13, 1884. It was followed by 11.2 degrees Celsius on January 9, 1992; 11.3 degrees Celsius on January 6, 1992; 11.4 degrees Celsius on January 5, 1977; 11.5 degrees Celsius on January 15, 1990; 11.6 degrees Celsius on January 19, 1993, and 11.7 degree Celsius on January 3, 1993. on January 2, 2019 it was recorded at 12.4 degrees Celsius.