WTIN20 DEMS 020924

TROPICAL WEATHER OUTLOOK
DEMS-RSMC TROPICAL CYCLONES NEW DELHI DATED 02.04.2021

SPECIAL TROPICAL WEATHER OUTLOOK FOR NORTH INDIAN OCEAN (THE BAY OF
BENGAL AND ARABIAN SEA) VALID FOR NEXT 120 HOURS ISSUED AT 0900 UTC OF 02.04.2021 BASED ON 0600 UTC OF 02.04.2021.

BAY OF BENGAL:
THE DEPRESSION OVER NORTH ANDAMAN SEA & NEIGHBOURHOOD MOVED NORTH-NORTHEASTWARDS AND LAY CENTRED AT 0600 UTC OF TODAY, THE 02ND
APRIL, 2021 NEAR LATITUDE 11.2ON AND LONGITUDE 96.4OE, ABOUT 410 KM EAST-NORTHEAST OF PORT BLAIR (43333), 430 KM NORTH-NORTHWEST OF PHUKET
(48564) AND 620 KM SOUTH OF YANGON (48097). IT IS LIKELY TO MOVE NORTH-NORTHEASTWARDS TOWARDS MYANMAR COAST. IT IS LIKELY TO INTENSIFY INTO
A DEEP DEPRESSION DURING NEXT 12 HOURS.

FORECAST TRACK AND INTENSITY ARE GIVEN IN THE FOLLOWING TABLE:

DATE/TIME(UTC) POSITION MAXIMUM SUSTAINED SURFACE
CATEGORY OF CYCLONIC
0 0
(LAT. N/ LONG. E) WIND SPEED (KMPH)
DISTURBANCE
02.04.21/0600 11.2/96.4 45-55 GUSTING TO 65
DEPRESSION
02.04.21/1800 11.8/96.7 50-60 GUSTING TO 70
DEEP DEPRESSION
03.04.21/0600 12.6/97.2 45-55 GUSTING TO 65
DEPRESSION
03.04.21/1800 13.4/97.5 40-50 GUSTING TO 60
DEPRESSION

THE ESTIMATED MAXIMUM SUSTAINED WIND SPEED IS 25 KNOTS GUSTING TO 35
KNOTS. THE SEA CONDITION IS ROUGH TO VERY ROUGH AROUND THE SYSTEM
CENTER. THE ESTIMATED CENTRAL PRESSURE IS 1000 HPA.

AS PER INSAT-3D IMAGERY AT 0600 UTC OF 02ND APRIL, THE INTENSITY OF
THE SYSTEM IS T 1.5. THE CONVECTION IS ORGANISED AS SHEAR PATTERN.
CONVECTIVE CLOUDS CLUSTERS ARE SHEARED TO NORTH. THREE CONVECTIVE
CLOUD CLUSTERS HAVE FORMED IN THE NORTHERN SECTOR OF THE SYSTEM IN
LAST 3 HOURS. THE AREA OF VERY INTENSE CONVECTION (-93OC) LAY OVER
NORTH ANDAMAN SEA & ADJOINING ANDAMAN ISLANDS TO THE NORTH OF
SYSTEM CENTER. BROKEN LOW & MEDIUM CLOUDS WITH EMBEDDED INTENSE TO
VERY INTENSE CONVECTION LAY OVER NORTH ANDAMAN SEA AND ADJOINING
ANDAMAN ISLANDS BETWEEN LATITUDE 10. 5ON & 15.5ON AND LONGITUDE
91.0OE & 97.0OE. MINIMUM CLOUD TOP TEMPERATURE IS -93OC.

REMARKS:
THE MADDEN JULIAN OSCILLATION (MJO) INDEX LIES CURRENTLY IN PHASE 5
WITH AMPLITUDE MORE THAN 1. IT WILL CONTINUE IN SAME PHASE TILL 3RD
APRIL. THEREAFTER, IT WILL MOVE TO PHASE 6 WITH AMPLITUDE REMAINING MORE
THAN 1 AND WILL REMAIN IN SAME PHASE FOR SUBSEQUENT 3 DAYS. THUS, MJO
PHASE AND AMPLITUDE WILL SUPPORT ENHANCEMENT OF CONVECTIVE ACTIVITY OVER
THE ANDAMAN SEA AND ADJOINING AREAS TILL 3RD APRIL AND WILL BECOME
UNFAVOURABLE FROM 3RD ONWARDS. THUS, THE LARGE SCALE PROCESS LIKE
MJO WILL SUPPORT INTENSIFICATION OF THE SYSTEM TILL 3RD APRIL ONLY.

THE LOW LEVEL POSITIVE VORTICITY HAS NOT CHANGED DURING PAST 06
HOURS AND IS ABOUT 80-90 X10-6SEC-1 OVER ANDAMAN SEA TO THE SOUTHEAST
OF THE SYSTEM CENTRE. THE MAGNITUDE OF POSITIVE LOW LEVEL
CONVERGENCE OVER THE SYSTEM AREA REMAINED SAME DURING PAST 06
HOURS (15-20 X10-5 SEC-1). THE POSITIVE UPPER LEVEL DIVERGENCE REMAINS ORGANISED W ITH NO CHANGE IN MAGNITUDE (30X10-5 SEC-1) DURING PAST 06
HOURS AND IT LAY OVER THE SYSTEM CENTRE. IT IS COUPLED WITH THE LOW
LEVEL CONVERGENCE ZONE. CURRENTLY, A WEAK OUTFLOW PREVAILS IN THE
UPPER LEVELS. VERTICAL WIND SHEAR (VWS) IS MODERATE (15-20 KTS) OVER
NORTH ANDAMAN SEA ALONG THE FORECAST TRACK. AS THE SYSTEM MOVES NORTH-NORTHEASTWARDS, THE FAVOURABLE WIND SHEAR ZONE WOULD
CONTINUE FOR SOME MORE TIME, AIDING THE INTENSIFICATION OF THE SYSTEM
FURTHER INTO A DEEP DEPRESSION MARGINALLY. THEREAFTER, IT WILL
GRADUALLY ENTER INTO AN AREA OF HIGH VWS, ESPECIALLY FROM 4TH APRIL
ONWARDS. THE UPPER TROPOSPHERIC RIDGE RAN ALONG 13ON OVER THE BOB.
UNDER THE INFLUENCE OF THE ANTICYCLONIC CIRCULATION OVER SOUTHEAST
ASIA AND MID TROSPHERIC WESTERLIES THE DEPRESSION WOULD MOVE NORTH- NORTHEASTWARDS TOWARDS MYANMAR COAST.

THE TROPICAL CYCLONE HEAT POTENTIAL OVER THE REGION IS AROUND 80
KJ PER SEC AND THE SEA SURFACE TEMPERATURES ARE 29-30 DEG.C OVER THE
REGION.

THE SYSTEM IS LYING IN A FAVOURABLE ENVIRONMENT. A FEW MODELS
ARE INDICATING FURTHER INTENSIFICATION OF THE SYSTEM DURING NEXT 12
HOURS W ITH NORTH-NORTHEASTWARDS MOVEMENT TOWARDS MYANMAR COAST
AND WEAKENING THEREAFTER. HOWEVER THE PROBABILITY OF BECOMING A
CYCLONIC STORM IS VERY LOW OWING TO THE INCREASING VWS TENDENCY AND UNFAVOURABLE MJO CONDITIONS FROM 4TH ONWARDS.

CONSIDERING ALL THESE, THE DEPRESSION OVER NORTH ANDAMAN SEA IS
LIKELY TO INTENSIFY MARGINALLY INTO A DEEP DEPRESSION BY 1800 UTC OF
02ND APRIL AND GRADUALLY WEAKEN THEREAFTER. IT WOULD CONTINUE TO MOVE NORTH-NORTHEASTWARDS TOWARDS MYANMAR COAST DURING NEXT 36 HOURS.
NEXT BULLETIN WILL BE ISSUED AT 1500 UTC OF 02ND APRIL 2021.
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WTIN20 DEMS 232200
REGIONAL SPECIALISED METEOROLOGICAL CENTRE-TROPICAL CYCLONES, NEW
DELHI SPECIAL TROPICAL WEATHER OUTLOOK

DEMS-RSMC TROPICAL CYCLONES NEW DELHI DATED 23.05.2021



SPECIAL TROPICAL WEATHER OUTLOOK FOR NORTH INDIAN OCEAN (THE BAY OF
BENGAL AND ARABIAN SEA) VALID FOR NEXT 120 HOURS ISSUED AT 2130 UTC
OF 23.05.2021 BASED ON 1800 UTC OF 23.05.2021.



SUB: DEPRESSION OVER EASTCENTRAL BAY OF BENGAL INTENSIFIED INTO A
DEEP DEPRESSION OVER EASTCENTRAL BAY OF BENGAL



THE DEPRESSION OVER EASTCENTRAL BAY OF BENGAL MOVED
WEST-NORTHWESTWARDS WITH A SPEED OF 4 KMPH DURING PAST 6 HOURS,
INTENSIFIED INTO A DEEP DEPRESSION AND LAY CENTRED AT 1800 UTC OF
TODAY, THE 23RD MAY, 2021 NEAR LATITUDE 16.3ON AND LONGITUDE 89.7OE,
ABOUT 600 KM NORTH-NORTHWEST OF PORT BLAIR (43333), 540 KM
SOUTH-SOUTHEAST OF PARADIP (42976), 650 KM SOUTH-SOUTHEAST OF
BALASORE (42895), 630 KM SOUTH-SOUTHEAST OF DIGHA (42901) AND 620 KM
SOUTH OF KHEPUPARA(41984).

IT IS VERY LIKELY TO MOVE SLOWLY NORTH-NORTHWESTWARDS AND INTENSIFY
INTO A CYCLONIC STORM BY 24TH MAY MORNING (AROUND 0000 UTC) AND
FURTHER INTO A VERY SEVERE CYCLONIC STORM DURING THE SUBSEQUENT 24
HOURS. IT WOULD CONTINUE TO MOVE NORTH-NORTHWESTWARDS, INTENSIFY
FURTHER AND REACH NORTHWEST BAY OF BENGAL NEAR NORTH ODISHA AND WEST
BENGAL COASTS BY 26TH MAY MORNING (AROUND 0000 UTC). IT IS VERY
LIKELY TO CROSS NORTH ODISHA - WEST BENGAL COASTS BETWEEN
PARADIP(42976) AND SAGAR ISLANDS(42903) BY EVENING (0900-1200 UTC) OF
26TH MAY AS A VERY SEVERE CYCLONIC STORM.

FORECAST TRACK AND INTENSITY ARE GIVEN IN THE FOLLOWING TABLE:

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


23.05.21/1800 16.3/89.7 50-60 GUSTING TO 70 DEEP DEPRESSION

24.05.21/0000 16.7/89.6 60-70 GUSTING TO 80 CYCLONIC STORM

24.05.21/0600 17.0/89.5 70-80 GUSTING TO 90 CYCLONIC STORM

24.05.21/1200 17.3/89.4 80-90 GUSTING TO 100 CYCLONIC STORM

24.05.21/1800 17.6/89.1 100-110 GUSTING TO 120 SEVERE CYCLONIC
STORM

25.05.21/0600 18.5/88.5 120-130 GUSTING TO 145 VERY SEVERE CYCLONIC
STORM

25.05.21/1800 20.0/87.9 150-160 GUSTING TO 180 VERY SEVERE CYCLONIC
STORM

26.05.21/0600 21.3/87.3 160-170 GUSTING TO 190 VERY SEVERE CYCLONIC
STORM

26.05.21/1800 22.2/86.7 90-100 GUSTING TO 110 SEVERE CYCLONIC
STORM

27.05.21/0600 23.0/86.1 30-40 GUSTING TO 50 DEPRESSION

THE MAXIMUM SUSTAINED WIND SPEED IS 30 KNOTS GUSTING TO 40 KNOTS
AROUND SYSTEM CENTRE. SEA CONDITION IS ROUGH TO VERY ROUGH. THE
ESTIMATED CENTRAL PRESSURE IS 996 HPA. A BUOY (23092) NEAR
17.5N/89.0E REPORTED MAXIMUM SUSTAINED WIND OF 40O/17.5 KTS. ANOTHER
BUOY (23459) NEAR 13.8N/87.1E REPORTED MAXIMUM SUSTAINED WIND OF
290O/21 KTS AND MEAN SEA LEVEL PRESSURE OF 1000.5 HPA.

AS PER SATELLITE IMAGERY BASED ON 1800 UTC OF TODAY, THE 23RD MAY,
THE CLOUD MASS IS ORGANISED IN SHEAR PATTERN. INTENSITY OF THE SYSTEM
IS CHARACTERISED AS T 2.0. BROKEN LOW AND MEDIUM CLOUDS WITH EMBEDDED
INTENSE TO VERY INTENSE CONVECTION LAY OVER THE AREA BETWEEN LATITUDE
7.0ON & 20.0ON AND 82.0OE & 93.0OE AND ANDAMAN ISLANDS. MINIMUM CLOUD
TOP TEMPERATURE IS 93OCELCIUS.

REMARKS:

THE MADDEN JULIAN OSCILLATION (MJO) INDEX CURRENTLY LIES IN PHASE 5
WITH AMPLITUDE MORE THAN 1 AND WILL CONTINUE IN SAME PHASE TILL 24TH
MAY. THUS, MJO IS CONDUCIVE FOR ENHANCED CONVECTION OVER THE BAY OF
BENGAL (BOB) DURING NEXT 2 DAYS. THE TROPICAL CYCLONE HEAT POTENTIAL
(TCHP) IS MORE THAN 100 KJ/CM2 OVER MAJOR PARTS OF BOB. IT IS
SLIGHTLY DECREASING OVER EXTREME NORTH BOB AND ALONG & OFF ANDHRA,
ODISHA, WEST BENGAL COASTS. SEA SURFACE TEMPERATURE (SST) IS AROUND
30-310C OVER MAJOR PARTS OF BOB.

EASTERLY WINDS ARE PREVAILING IN THE UPPER LEVEL. UPPER TROPOSPHERIC
RIDGE RUNS ALONG 22.50N. A NORTHEAST-SOUTHWEST ORIENTED LOWER LEVEL
POSITIVE VORTICITY ZONE 150X10-5 S-1 IS PREVAILING AROUND SYSTEM
CENTRE WITH VERTICAL EXTENSION UPTO 200 HPA LEVEL. A
NORTHWEST-SOUTHEAST ORIENTED LOWER LEVEL POSITIVE CONVERGENCE ZONE
(40-50 X 10-5 S-1) LAY TO THE SOUTHWEST OF SYSTEM CENTRE AND
EAST-WEST ORIENTED ZONE OF POSITIVE UPPER LEVEL DIVERGENCE (30-40 X
10-5 S-1) LAY OVER ENTIRE CENTRAL BOB. MODERATE VERTICAL WIND SHEAR
(VWS) (10-20 KTS) IS PREVAILING OVER CENTRAL & NORTH BOB TO THE NORTH
OF 15ON AND IS DECREASING BECOMING LOW (5-10 KTS) OVER NORTH BAY OF
BENGAL OFF NORTH ODISHA & WEST BENGAL COASTS. THE SEA CONDITIONS AND
EXISTING ENVIR0ONMENTAL FEATURES LIKE ENHANCED LOW LEVEL VORTICITY,
LOWER LEVEL CONVERGENCE, EQUATORWARD & POLEWARD OUTFLOW, MODERATE
VERTICAL WIND SHEAR ARE CONDUCIVE FOR FURTHER INTENSIFICATION OF THE
SYSTEM INTO A CYCLONIC STORM DURING NEXT 12 HOURS.

MOST OF THE NUMERICAL MODELS INCLUDING IMD GFS, NCEP GFS, ECMWF AND
NCUM ARE UNANIMOUSLY INDICATING NORTH-NORTHWESTWARD MOVEMENT TOWARDS
NORTH ODISHA AND WEST BENGAL COASTS. MODELS ARE UNANIMOUSLY
INDICATING RAPID INTENSIFICATION OF SYSTEM UPTO VERY SEVERE CYCLONIC
STORM CATEGORY. CONSIDERING THE MEAN MODEL GUIDANCE, THE SYSTEM IS
EXPECTED TO REACH NORTH BAY OF BENGAL NEAR NORTH ODISHA AND WEST
BENGAL COASTS AROUND 26TH MAY MORNING (AROUND 0000 UTC). IT IS VERY
LIKELY TO CROSS NORTH ODISHA AND WEST BENGAL COASTS BETWEEN
PARADIP(42976) AND SAGAR ISLANDS(42903) AROUND EVENING (0900- 1200
UTC) OF 26TH MAY.

IN VIEW OF ABOVE, IT IS INFERRED THAT THE SYSTEM IS VERY LIKELY TO
MOVE NORTH-NORTHWESTWARDS AND INTENSIFY INTO A CYCLONIC STORM BY 24TH
MAY MORNING (AROUND 0000 UTC) AND FURTHER INTO A VERY SEVERE CYCLONIC
STORM DURING THE SUBSEQUENT 24 HOURS. IT WOULD CONTINUE TO MOVE NORTH-NORTHWESTWARDS, INTENSIFY FURTHER AND REACH NORTHWEST BAY OF
BENGAL NEAR NORTH ODISHA AND WEST BENGAL COASTS BY 26TH MAY MORNING
(0000-0300 UTC). IT IS VERY LIKELY TO CROSS NORTH ODISHA AND WEST
BENGAL COASTS. BETWEEN PARADIP(42976) AND SAGAR ISLANDS(42903) BY
EVENING (0900- 1200 UTC) OF 26TH MAY AS A VERY SEVERE CYCLONIC STORM.
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