Minimum (night) temperatures are up over North-West and adjoining East India in anticipation of arrival of three back-to-back western disturbances with accompanying moisture and clouds. The night minima are, however, below normal over parts of Bihar, isolated parts of East Uttar Pradesh, Jharkhand and West Bengal which are out of range, and under colder and denser air.
The lowest minimum temperature recorded during the 24 hours ending on Monday morning is 5.0 °C at Sabaur in Bihar, the India Meteorological Department (IMD) said. Incoming moisture filtering into the prevailing cold air will also trigger heavy rainfall or snowfall in the Himalayas and dense to very dense fog in the plains for the next two to three days.
Welcome change in weather
This will be a welcome change from the predominantly dry winter on view thus far over North India, with IMD predicting isolated heavy rainfall/snowfall over Kashmir on Tuesday and Wednesday; Himachal Pradesh on Wednesday and Thursday; Uttarakhand on Wednesday; and Arunachal Pradesh on Friday. As for the plains, light to moderate isolated to scattered rain is likely over Punjab, Chandigarh, Haryana and Uttar Pradesh on Wednesday and Thursday. Isolated hailstorms may break out along the hills of West Bengal and Sikkim on Wednesday and Friday.
Offspring circulations
Short to medium forecasts signal the western disturbances on a trot triggering the formation of a cyclonic circulation (if not more) over South-West Rajasthan, which would likely help sweep in incremental moisture from the North Arabian Sea (off Gujarat). Western disturbances accompanied by offspring circulations favourably positioned over Rajasthan are instrumental in generating winter-time rainfall over North-West India, but have been conspicuous by their absence through this winter.
Rainy week ahead?
International models believe the ‘threesome’ western disturbances would be able to sustain the rain in variable amounts over North-West India and adjoining East India at least through the first week of February. The rain regime may even dip along the East Coast to East-Central India and Peninsular South-East India into mid-February. If this were to fructify, Odisha, Chhattisgarh, East Madhya Pradesh and Coastal Andhra Pradesh may benefit the most, per these models.
Wet spell for East, South
Parts of Tamil Nadu, Karnataka and Telangana are also forecast to make some gains as the western disturbance travels East and takes a dip to the South along the East Coast and runs into easterlies from the Bay of Bengal. Winds from the Bay would be initially swept in by a prevailing anticyclonic circulation, to be replaced by south-westerly winds along the coast as the anticyclone retrogrades and moves out to the central parts of the Bay towards the end of first week of February.