The Cyclone VAYU formed over adjoining East Central Arabian sea in the night of 10th June 2019. Initially it moved northerly and was expected to make landfall over Gujrat. However, on 12th July 2019 when it reached 300km away from Veraval the cyclone moved Northwesterly. It moved parallel to the Saurashtra coast along Porbandar coast and remained in the sea. It’s rare that inspite of being Very Severe, the cyclone is still in the sea for almost 2 days and expected to remain in the sea till 17th morning and then dissipate.
The reason behind the Cyclone remaining stationary or lingering in the same area may be because of the Col region. This Col region persists at upper level upto 14kms (200 hPa).
What is COL?
COL is a point of intersection of a trough (belt of anti-clockwise winds or cyclonic winds) and a ridge (belt of clockwise winds or anti cyclonic winds). On weather map it can be seen in pressure pattern as shown in figure. The anticyclones which persists at upper level upto 14kms (200 hpa) acts as driving instrument (steering winds) of a Cyclone. When this Cyclone is captured by a Col then it does not move in any direction rather it remains stationary over the area. Dissipating process takes place because of less temperature of sea surface.
VAYU stuck in COL
Why Very Severe Cyclonic Storm “VAYU” lingering over North Arabian sea?
In continuation with above explanation the Cyclone approached Gujarat coast near Veraval about 300 km. The steering winds at 200 hPa has been westwards and thus northward moving Very Severe Cyclonic Storm Vayu changed its resultant direction to North-northwest wards. It resulted in skirting along Saurashtra coast. Due to this movement it’s further advancement over North Arabian sea, it was blocked by COL region. Thus, Vayu is lingering over North Arabian sea being stuck in the COL. Further as it encountering lower SST in the north Arabian sea it is unable to intensify further and hence it will gradually weaken.
In the past also some cyclone has behaved like VAYU.