By Sanjeev Kumar Patro
Bhubaneswar: The usual suspect Bay of Bengal has given a blank this year. The cooler and calmer Arabian seas seem hot enough to brew a severe cyclone around Dussehra. The state of Karnataka will record heavy to very heavy rainfall on the Dussehra day – when the State holds the famous chamunda Devi yatra on the scared day.
The model forecasts of all reputed weather forecasters worldwide are unanimous on the cyclone genesis in the Arabian seas on and around Oct 11. And the system will intensify into a severe or extremely severe cyclone by around Oct 16/17. However, the models still are yet to display convergence on the place of landfall and date of landfall.
ACTIVE MJO
Saddling with a high tropical cyclone heat potential of around d100kjcm2 and a sea surface temperature of over 32 deg C in the south Arabian seas, the Madden Julian Oscillation (MJO) will became active over the Arabian seas in next 48 hours. This high convective activities band will seed the genesis of a cyclonic circulation over south Arabian seas on and around October 10.
DATE DIFFERENCE
It seems model differ over the birth date of the likely system in the Arabian seas. While the premiere weather model developer National Centre for Medium Range Weather Forecast’s (NCMWRF) NCUM global model predicts the date of low pressure formation on Oct 9, the national weather forecaster’s IMD’s GFS model see the LPA forming on and around October 13.
While NCUM global model is forecasting the LPA to become cyclone in next 48 hrs, i.e by around Oct 11, IMD’s GFS forecast predict the system becoming depression by Oct 13.
HEAVY RAINS IN KARNATAKA
In deference to the differences on cyclone genesis timeline, both NCUM and IMD-GFS didn’t agree on heavy rains lashing the states of Karnataka and Kerala on Oct 13 – the day of Dussehra this year.
As per IMD model forecast rainfall in the range of 20mm is likely at many places in Karnataka form October 7. However, on Oct 13, the rainfall activities will be heightened and the prediction is rainfall in the range of 20-40 likely over many places in the state of Karnataka.
More than 40 mm rainfall is predicted for the states of Karnataka and Kerala on October 14. The rains will extend to Maharashtra from Oct 15 onwards.
On the other hand, NCUM has predicted moderate to heavy rainfall in Karnataka and Kerala from October 7-10. The model didn’t see chances of heavy rainfall on Dussehra day in the State.
GLOBAL MODEL CUES
A glance at the global model forecasts hints at the following.
- Global forecaster ECMWFpredicts heavy rain in Karnataka, Kerala on October 13 – Dussehra day.
- The model predicts very heavy rain on October 14.
- Another global forecaster of repute, NCEP-GFS predicts moderate rainfall in Karnataka and Kerala on Oct 13, with some places recording heavy rainfall.
- On Oct 14, the model predicts very heavy rainfall at many places in Karnataka and Kerala.
LIKELY LANDFALL PLACE
The wind pattern over the Indian continent from lower level of 1.5km to 12 km from the mean sea level predicted is as follows.
- The lower level wind over Arabian sea will see strong westerlies in the south Arabian sea. .
- At the upper level, strong easterlies prevail for the next 48 hours from today..
- The system will track north-northwest and move to central Arabian seas.
- Under the influence of cross equatorial easterlies, the system will move to central Arabian seas on around Oct 10.
- The system track towards Oman, predicts NCMRWF’s NCUM
- ECMWF too predicts the system tracking towards Oman.
- But NCEP –GFS predicts the system tracking north direction after coming to central Arabian seas.
- The model predicts the extremely severe system hitting Gujarat-Pakistan coasts.
- IMD –GFS yet to drop any clues on likely landfall.
