####018006335#### WTIN20 DEMS 020742 REGIONAL SPECIALISED METEOROLOGICAL CENTRE-TROPICAL CYCLONES,NEW DELHI SPECIAL TROPICAL WEATHER OUTLOOK DEMS-RSMC TROPICAL CYCLONES NEW DELHI DATED 02.12.2023 SPECIAL TROPICAL WEATHER OUTLOOK FOR NORTH INDIAN OCEAN (THE BAY OF BENGAL AND THE ARABIAN SEA) VALID FOR NEXT 168 HOURS ISSUED AT 0700 UTC OF 02.12.2023 BASED ON 0300 UTC OF 02.12.2023. SUB: DEEP DEPRESSION OVER SOUTHWEST BAY OF BENGAL (CYCLONE ALERT FOR ANDHRA PRADESH AND ADJOINING NORTH TAMIL NADU- PUDUCHERRY COASTS: YELLOW MESSAGE) THE DEEP DEPRESSION OVER SOUTHWEST BAY OF BENGAL MOVED WEST- NORTHWESTWARDS WITH A SPEED OF 18 KMPH DURING PAST 06 HOURS AND LAY CENTERED AT 0300 UTC OF TODAY, THE 2 ND DECEMBER, 2023 OVER THE SAME REGION NEAR LATITUDE 10.6ON AND LONGITUDE 83.6OE, ABOUT 440 KM EAST- SOUTHEAST OF PUDUCHERRY (43331), 450 KM EAST-SOUTHEAST OF CHENNAI (43279), 580 KM SOUTH-SOUTHEAST OF NELLORE (43245), 670 KM SOUTH- SOUTHEAST OF BAPATLA (43220) AND 670 KM SOUTH-SOUTHEAST OF MACHILIPATNAM (43185). IT IS LIKELY TO MOVE WEST-NORTHWESTWARDS AND INTENSIFY INTO A CYCLONIC STORM OVER SOUTHWEST BAY OF BENGAL DURING NEXT 24 HOURS. THEREAFTER, IT WOULD MOVE NORTHWESTWARDS AND REACH WESTCENTRAL BAY OF BENGAL OFF SOUTH ANDHRA PRADESH AND ADJOINING NORTH TAMILNADU COASTS BY 0600 UTC OF 4 TH DECEMBER. THEREAFTER, IT WOULD MOVE NEARLY NORTHWARDS ALMOST PARALLEL AND CLOSE TO SOUTH ANDHRA PRADESH COASTS AND CROSS SOUTH ANDHRA PRADESH COASTS BETWEEN NELLORE AND MACHILIPATNAM AROUND 0600 UTC OF 5 TH DECEMBER AS A CYCLONIC STORM WITH A MAXIMUM SUSTAINED WIND SPEED OF 80-90 KMPH GUSTING TO 100 KMPH. TRACK & INTENSITY FORECASTS: DATE/TIME POSITION MAXIMUM SUSTAINED SURFACE CATEGORY OF CYCLONIC (LAT. 0N/ LONG.0E) WIND SPEED (KMPH) DISTURBANCE (UTC) 02.12.23/0300 10.6/83.6 50-60 KMPH GUSTING TO 70 KMPH DEEP DEPRESSION 02.12.23/0600 10.7/83.2 50-60 KMPH GUSTING TO 70 KMPH DEEP DEPRESSION 02.12.23/1200 11.0/82.6 55-65 KMPH GUSTING TO 75 KMPH DEEP DEPRESSION 02.12.23/1800 11.4/82.2 60-70 KMPH GUSTING TO 80 KMPH CYCLONIC STORM 03.12.23/0000 11.8/81.9 65-75 KMPH GUSTING TO 85 KMPH CYCLONIC STORM 03.12.23/1200 12.6/81.4 70-80 KMPH GUSTING TO 90 KMPH CYCLONIC STORM 04.12.23/0000 13.5/80.9 75-85 KMPH GUSTING TO 95 KMPH CYCLONIC STORM 04.12.23/1200 14.5/80.5 80-90 KMPH GUSTING TO 100 KMPH CYCLONIC STORM 05.12.23/0000 15.5/80.7 80-90 KMPH GUSTING TO 100 KMPH CYCLONIC STORM 05.12.23/1200 16.5/81.1 70-80 KMPH GUSTING TO 90 KMPH CYCLONIC STORM 06.12.23/0000 17.6/82.2 45-55 KMPH GUSTING TO 65 KMPH DEPRESSION 06.12.23/1200 18.5/83.6 35-45 KMPH GUSTING TO 55 KMPH DEPRESSION INSAT -3D IMAGERY AT 0300 UTC, INDICATE FURTHER ORGANISATION OF CLOUD MASS. ASSOCIATED INTENSITY IS T2.0. ASSOCIATED SCATTERED TO BROKEN LOW/MEDIUM CLOUDS WITH EMBEDED INTENSE TO VERY INTENSE CONVECTION LAY OVER SOUTH AND ADJOINING CENTRAL BAY OF BENGAL BETWEEN LATITUDE 5.0ON TO 16.0ON LONGITUDE 80.0E TO 90.0E. MINIMUM CLOUD TOP TEMPERATURE IS MINUS 92 DEGREE CELSIUS. ASSOCIATED MAXIMUM SUSTAINED WIND SPEED IS 30 KNOTS GUSTING TO 40 KNOTS. ESTIMATED CENTRAL PRESSURE IS 1000 HPA. SEA CONDITION IS LIKELY TO BE VERY ROUGH OVER THE SOUTHWEST & ADJOINING SOUTHEAST BAY OF BENGAL. MADDEN JULIAN OSCILLATION (MJO) IS CURRENTLY IN PHASE 3 WITH AMPLITUDE GREATER THAN 1. IT WOULD MOVE ACROSS PHASES 3 AND 4 WITH AMPLITUDE GREATER THAN 1 DURING 2 ND TO 6 TH DECEMBER. THUS, MJO WOULD SUPPORT CYCLOGENESIS OVER THE BAY OF BENGAL (BOB) REGION TILL 6 TH DECEMBER. SEA SURFACE TEMPERATURE ALONG 27 0 C. TROPICAL CYCLONE HEAT POTENTIAL IS 60-70 KJ/CM 2 OVER SOUTHWEST AND WESTCENTRAL BOB. THE NCICS BASED FORECASTS FOR EQUATORIAL WAVES INDICATE STRENGTHENING OF WESTERLY WINDS ALONGWITH PRESENCE OF EQUATORIAL ROSSBY WAVES & MJO OVER SOUTH BOB AND EASTERLY WINDS OVER CENTRAL BOB TILL 4 TH DECEMBER. ALL THESE LARGE SCALE FEATURES ARE FAVOURABLE FOR FURTHER INTENSIFICATION OF SYSTEM INTO A CYCLONIC STORM. CURRENT ENVIRONMENTAL FEATURES INDICATE, INCREASE IN POSITIVE LOW LEVEL VORTICITY TO 100X10 -6 S -1 AROUND SYSTEM CENTRE WITH VERTICAL EXTENSION UPTO 200 HPA LEVEL. THE VORTICITY FIELD SHOWS NO TILTING WITH HEIGHT. POSITIVE LOW LEVEL CONVERGENCE IS SAME DURING PAST 3 HOURS AND IS ABOUT 20 X 10 -5 S -1 TO THE SOUTHEAST OF SYSTEM CENTRE. POSITIVE UPPER LEVEL DIVERGENCE IS SAME AND IS ABOUT 30 X 10 -5 S -1 TO THE NORTHEAST OF THE SYSTEM CENTRE. WIND SHEAR IS ABOUT 10-20 KNOTS OVER SOUTH BOB AND UPTO 13 0 N. CLOCKWISE DEEP LAYER MEAN WIND SHEAR IS SUPPORTING FURTHER INTENSIFICATION OF SYSTEM. TOTAL PRECIPITABLE WATER IMAGERY IS INDICATING WARM MOIST AIR ADVECTION FROM SOUTHEAST SECTOR. UPPER TROPOSPHERIC RIDGE RUNS ALONG 14 0 N. FROM 4 TH DECEMBER/0000 UTC, THE SYSTEM WILL COME CLOSER TO THE RIDGE AND HENCE WOULD MOVE NEARLY NORTHWARDS AND BY 5 TH /0000 UTC, IT WOULD CROSS RIDGE AND HENCE RECURVE NORTHEASTWARDS FROM 5 TH DECEMBER/0000 UTC. UPPER TROPOSPHERIC WINDS ARE OF THE ORDER OF 50-60 KNOTS OVER NORTH ANDHRA PRADESH AND ODISHA COASTS. IT WOULD LEAD TO HIGHER WIND SHEAR MOST OF THE MODELS ARE INDICATING INTIAL WEST-NORTHWESTWARDS MOVEMENT FOLLOWED BY NORTHWESTWARDS MOVEMENT TOWARDS ANDHRA PRADESH COAST. THE LANDFALL POINT IS VARYING BETWEEN LATITUDE 15.5-16.5 0 N/80.0-82.0 0 E. HOWEVER, NCUM MODEL IS INDICATING LANDFALL NEAR 13.3N/80.1E. IMD MME IS INDICATING LANDFALL NEAR 16.3N/81.2E. THE LANDFALL TIME IS VARYING BETWEEN 4 TH /1800 UTC TO 5 TH /1500 UTC. CONSIDERING ALL THE ABOVE, THE DEEP DEPRESSION OVER SOUTHWEST BAY OF BENGAL IS LIKELY TO MOVE WEST-NORTHWESTWARDS, INTENSIFY INTO A CYCLONIC STORM OVER SOUTHWEST BAY OF BENGAL DURING NEXT 24 HOURS. THEREAFTER, IT WOULD MOVE NORTHWESTWARDS AND REACH WESTCENTRAL BAY OF BENGAL OFF SOUTH ANDHRA PRADESH AND ADJOINING NORTH TAMILNADU COASTS BY 0600 UTC OF 4TH DECEMBER. THEREAFTER, IT WOULD MOVE NEARLY NORTHWARDS ALMOST PARALLEL AND CLOSE TO SOUTH ANDHRA PRADESH COASTS AND CROSS SOUTH ANDHRA PRADESH COASTS BETWEEN NELLORE AND MACHILIPATNAM AROUND 0600 UTC OF 5TH DECEMBER AS A CYCLONIC STORM WITH A MAXIMUM SUSTAINED WIND SPEED OF 80-90 KMPH GUSTING TO 100 KMPH.=