Tropical Storm "Sagar‟ Advisory No. Four Issued at 1400 UTC of 17th May 2018 based on 1200 UTC of 17th May 2018

Report
from Government of India
Published on 17 May 2018 View Original

REGIONAL SPECIALISED METEOROLOGICAL CENTRE-TROPICAL CYCLONES, NEW DELHI TROPICAL CYCLONE ADVISORY BULLETIN

THE CYCLONIC STORM “SAGAR” OVER GULF OF ADEN MOVED FURTHER WESTWARDS WITH A SPEED OF 5 KMPH DURING PAST 6 HOURS, AND LAY CENTERED AT 1200 UTC OF TODAY, THE 17TH MAY 2018 OVER GULF OF ADEN NEAR LATITUDE 13.0ºN AND LONGITUDE 48.1º E; ABOUT 330 KM EAST-NORTHEAST OF ADEN (41480) AND 620 KM WEST-NORTHWEST OF SOCOTRA ISLANDS (41494). IT IS VERY LIKELY TO INTENSIFY FURTHER SLIGHTLY DURING NEXT 12 HRS.

IT IS VERY LIKELY TO MOVE WEST-SOUTHWESTWARDS.

AS PER THE LATEST SATELLITE IMAGERY, THE INTENSITY OF THE SYSTEM IS T2.5.
ASSOCIATED SCATTERED LOW & MEDIUM CLOUDS WITH EMBEDDED INTENSE TO VERY INTENSE CONVECTION LIE OVER AREA BETWEEN LATTITUDE 12.0 0N TO 17.00N AND LONGITUDE 44.00 E TO 50.00 E GULF OF ADEN AND ADJOINING SAUDI ARABIA AND YEMEN.

THE ESTIMATED CENTRAL PRESSURE IS ABOUT 996 HPA AND THE MAXIMUM SUSTAINED SURFACE WIND SPEED IS 40 KNOTS GUSTING TO 50 KNOTS. STATE OF SEA IS HIGH AROUND THE SYSTEM CENTRE.

REMARKS:
THE SEA SURFACE TEMPERATURE (SST) IS 30-320 C OVER THE SYSTEM AREA. THE TROPICAL CYCLONE HEAT POTENTIAL IS ABOUT 80-100 KJ/CM2 OVER THE REGION OF THE SYSTEM. THERE IS A MAXIMA OF VALUE 30X10-5 S -1 IN LOW LEVEL CONVERGENCE TO THE WEST OF THE SYSTEM CENTRE. THE UPPER LEVEL DIVERGENCE IS ABOUT 20X10-5 S -1 AROUND THE SYSTEM CENTRE. VORTICITY AT 850 HPA LEVEL IS ABOUT 100X10-6 S -1 IN THE SOUTH-SOUTHEAST OF THE SYSTEM CENTRE AND IS EXTENDING UPTO 500 HPA LEVEL.
VERTICAL WIND SHEAR IS LOW TO MODERATE (10-15 KTS) AROUND THE SYSTEM CENTRE. IT INCREASES TOWARDS YEMEN AND OMAN COASTS. UPPER TROPOSPHERIC RIDGE LIES ALONG LATITUDE 16.00N NEAR LONGITUDE 500 E. IT IS FAVOURING POLEWARD OUTFLOW AND HENCE INCREASING THE UPPER LEVEL DIVERGENCE. THE MADDEN JULIAN OSCILLATION (MJO) INDEX NOW LIES OVER PHASE 1 WITH AMPLITUDE GREATER THAN 1. IT IS EXPECTED TO MOVE EASTWARDS AND REACH NEAR PHASE 2 AROUND 18TH MAY 2018. HENCE THE MJO WILL BE FAVOURABLE FOR INTENSIFICATION.

THE MIDDLE AND UPPER LEVEL WINDS INDICATE THAT THE SYSTEM WOULD MOVE INITIALLY WESTWARDS DURING NEXT 12 HOURS AND THEN WEST-SOUTHWESTWARDS ACROSS GULF OF ADEN DURING SUBSEQUENT 24 HRS. UNDER FAVOURABLE SST AND ENVIRONMENTAL CONDITIONS LIKE VERTICAL WIND SHEAR AND UPPER LEVEL DIVERGENCE,

THE SYSTEM WOULD INTENSIFY FURTHER DURING NEXT 12 HRS. NWP MODELS ARE IN AGREEMENT WITH ABOVE CONSENSUS.

(NARESH KUMAR)
SCIENTIST-E, RSMC, NEW DELHI