WTIN20 DEMS 121530
SPECIAL TROPICAL WEATHER OUTLOOK

DEMS-RSMC TROPICAL CYCLONES NEW DELHI DATED 12.10.2020

SPECIAL TROPICAL WEATHER OUTLOOK FOR NORTH INDIAN OCEAN (THE BAY
OF BENGAL AND ARABIAN SEA) VALID FOR NEXT 120 HOURS ISSUED AT
1500 UTC OF 12.10.2020 BASED ON 1200 UTC OF 12.10.2020.

BAY OF BENGAL:

THE DEEP DEPRESSION OVER WESTCENTRAL BAY OF BENGAL MOVED
NORTHWESTWARDS
WITH A SPEED OF 05 KMPH DURING PAST 06 HOURS AND LAY CENTRED AT 1200
UTC OF 12TH OCTOBER, 2020 NEAR LATITUDE 16.1ON AND LONGITUDE 84.6OE,
ABOUT 220 KM SOUTH-SOUTHEAST OF VISHAKHAPATNAM (43149), 270 KM
EAST-SOUTHEAST OF KAKINADA (43189) AND 310 KM EAST-SOUTHEAST OF
NARSAPUR (43187).

IT IS VERY LIKELY TO MOVE WEST-NORTHWESTWARDS AND CROSS NORTH
ANDHRA PRADESH COAST AROUND 0300-0600 UTC OF 13TH OCTOBER BETWEEN NARSAPUR(43187) AND VISHAKHAPATNAM(43149), CLOSE TO KAKINADA (43189)
AS A DEEP DEPRESSION WITH WIND SPEED OF 55-65 KMPH GUSTING TO 75 KMPH

THE DEEP DEPRESSION IS BEING MONITORED BY COASTAL DOPPLER WEATHER
RADARS OF MACHILIPATNAM(43185), VISAKHAPATNAM(43149) AND
GOPALPUR(43049). AS PER RADAR IMAGERIES, THE RAIN BANDS LIE ALONG
THE COASTAL DISTRICTS OF ANDHRA PRADESH AND ADJOINING SEA AREAS.
MODERATE CONVECTION ALSO LIES OVER SOUTH ODISHA AND TELANGANA.

FORECAST TRACK AND INTENSITY ARE GIVEN IN THE FOLLOWING TABLE:

DATE/TIME POSITION MAXIMUM SUSTAINED SURFACE CATEGORY OF
(UTC) (LAT.ON/LONG.OE) WIND SPEED (KMPH) CYCLONIC
DISTURBANCE

12.10.20/1200 16.1/84.6 55-65 GUSTING TO 75 DEEP
DEPRESSION
12.10.20/1800 16.5/84.0 55-65 GUSTING TO 75 DEEP
DEPRESSION
13.10.20/0000 16.8/82.9 55-65 GUSTING TO 75 DEEP
DEPRESSION
13.10.20/0600 17.1/81.8 50-60 GUSTING TO 70 DEPRESSION 13.10.20/1200 17.4/80.7 45-55 GUSTING TO 65 DEPRESSION 14.10.20/0000 18.0/78.5 25-35 GUSTING TO 45 WELL MARKED
LOW


AS PER SATELLITE IMAGERY BASED ON 1200 UTC OF 12TH OCTOBER, INTENSITY
OF THE SYSTEM IS T 2.0. IT SHOWS SHEAR PATTERN. THE CLOUDS ARE
SHEARED TO THE WEST OF SYSTEM CENTRE. FURTHER, THE CONVECTIVE CLOUD
MASS HAS ENTERED INTO THE LAND INDICATING COMMENCEMENT OF INTERACTION
OF LAND WITH THE SYSTEM. SCATTERED LOW AND MEDIUM CLOUDS WITH
EMBEDDED INTENSE TO VERY INTENSE CONVECTION LAY OVER WESTCENTRAL
BAY OF BENGAL , SOUTH COASTAL ODISHA AND COASTAL ANDHRA PRADESH IN
ASSOCIATION WITH THE SYSTEM. MINIMUM CLOUD TOP TEMPERATURE IS -93OC.

NARSAPUR(43187) SHOWS MAXIMUM PRESSURE FALL OF 4.7 HPA FOLLOWED BY VISHAKHAPATNAM (43149) OF 4.5 HPA AND KAKINADA (43189) OF 3.9 HPA.

ARABIAN SEA:
SCATTERED LOW AND MEDIUM CLOUDS WITH EMBEDDED INTENSE TO VERY
INTENSE CONVECTION LAY OVER EASTCENTRAL ARABIAN SEA. SCATTERED LOW
AND MEDIUM CLOUDS WITH EMBEDDED ISOLATED MODERATE TO INTENSE
CONVECTION LAY OVER SOUTHEAST ARABIAN SEA.

THE NWP MODELS SUGGEST THAT THE REMNANT OF EXISTING DEPRESSION OVER
BAY OF BENGAL AFTER CROSSING THE PENINSULAR INDIA WOULD EMERGE INTO
EASTCENTRAL AND ADJOINING NORTHEAST ARABIAN SEA OFF NORTH
KONKAN-SOUTH
GUJARAT COASTS AS A LOW PRESSURE AREA AROUND 15TH MORNING. THERE IS
LOW TO MODERATE PROBABILITY FOR IT\U2019S INTENSIFICATION INTO A
DEPRESSION THEREAFTER OVER THE SAME REGION.

PROBABILITY OF CYCLOGENESIS(FORMATION OF DEPRESSION) DURING NEXT
120 HRS :

24 HOURS 24-48 HOURS 48-72 HOURS 72-96 HOURS 96-120 HOURS

NIL NIL NIL LOW MODERATE

REMARKS:

THE MADDEN JULIAN OSCILLATION (MJO) INDEX IS CURRENTLY IN PHASE 4
WITH AMPLITUDE MORE THAN 1. IT WILL CONTINUE IN SAME PHASE DURING
NEXT 24 HOURS. THEREAFTER, IT WILL MOVE TO PHASE 5 WITH AMPLITUDE
REMAINING MORE THAN 1. THUS, MJO WILL SUPPORT ENHANCEMENT OF
CONVECTIVE ACTIVITY OVER THE THE BAY OF BENGAL (BOB) FOR NEXT 5 DAYS. CONSIDERING THE SEA CONDITIONS, THE SEA SURFACE TEMPERATURE (SST)
IS 29- 30\U02DAC OVER ENTIRE BOB AND OVER ANDAMAN SEA. THE TROPICAL
CYCLONE HEAT POTENTIAL IS 80-90 KJ/CM2 OVER MAJOR PARTS OF SOUTH &
CENTRAL BOB AND ANDAMAN SEA.

CONSIDERING THE ENVIRONMENTAL CONDITIONS, THE VORTICITY IS ABOUT
100X10-6 SEC-1 AROUND THE SYSTEM CENTRE WITH VERTICAL EXTENSION UPTO
200 HPA LEVEL. LOWER LEVEL CONVERGENCE IS ABOUT 10X10-5SEC-1 TO THE
WEST OF SYSTEM CENTRE. THE UPPER LEVEL DIVERGENCE IS ABOUT
10X10-5SEC-1
ALSO TO THE WEST OF SYSTEM CENTRE BUT IS EAST-WEST ORIENTED. THE
VERTICAL WIND SHEAR (VWS) IS 10-15 KTS OVER WESTCENTRAL BOB AND
ALONG & OFF ANDHRA PRADESH-ODISHA COASTS. THE UPPER TROPOSPHERIC
RIDGE LIES NEAR 200N OVER NORTHEAST INDIA. EAST-SOUTHEASTERLY WINDS
ARE PREVAILING IN THE UPPER TROPOSPHERE OVER THE SYSTEM REGION.

MOST OF THE NWP MODELS AND PREVAILING UPPER TROPOSPHERIC STEERING
WIND PATTERN ARE INDICATING THAT THE SYSTEM WILL MOVE
WEST-NORTHWESTWARDS DURING NEXT 24 DAYS AND CROSS NORTH ANDHRA
PRADESH COAST AROUND 0300-0600 UTC OF 13TH OCTOBER 2020.=
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