BOB: INVEST 94B

[supercane4867]

18.9N 90.4E

[Grifforzer]

DEMS-RSMC TROPICAL CYCLONES NEW DELHI DATED 28-05-2013
TROPICAL WEATHER OUTLOOK FOR NORTH INDIAN OCEAN (THE BAY OF BENGAL AND ARABIAN SEA) VALID FOR NEXT 24 HOURS ISSUED AT 0600 UTC:

BAY OF BENGAL & ANDAMAN SEA:-

The upper air cyclonic circulation over northwest Bay of Bengal off west Bengal-Odisha coasts extending up to mid-tropospheric levels. Under it influence a low pressure area has formed over northern Bay of Bengal and neighborhood. It is likely to concentrate into a depression during the next 24 hours.

Vortex over northern Bay of Bengal near 20.5N 89.5E. Dvorak Intensity T1.0. Associated broken low medium clouds with embedded intense to very intense convection over Bay of Bengal north of 14.0N 82.5E to 92.0E, adjoining southern Gangetic, West Bengal and adjoining southern Bangladesh. Minimum cloud top temperature is -83C.

[Grifforzer]

Latest satellite imagery and observations indicate that a depression has formed over north bay of bengal and lay centred at 0300 utc of today, the29 Th May 2013 near latitude 21.0N and longitude 89.5E, about 130 km south-southwest of khepupara (41984)) and 200 km southeast of kolkata(42807). The System would move northwards and cross Bangladesh coast near long. 89.5N, about 50 km west of khepupara by today, the 29Th May 2013 evening.

Satellite based intensity of the system is t 1.5. Associated low/medium clouds with embbeded intense to very intense convection seen over bay of bengal, north of lat 13.0 And long 82.0E to 94E. The lowest cloud top temperature (ctt) is about -70C.

Sustained maximum surface wind speed is estimated to be about 25 knots Gusting to 35 knots around system centre. The state of the sea is rough to Very rough around the system centre. The estimated central pressure is About 996 hpa.

Remarks:
Scatterometry data indicates the cyclonic circulation over the region and Associated wind speed to be about 25-30 knots. Wind speed is relatively
Higher in southern sector. Khepupara reported mslp of 997.8 hpa with 24 hr pressure change of -3.2 hpa And surface wind of 090/10 kts at 0300 utc of today The upper tropospheric ridge runs along 23N in association with the Anticyclonic circulation located to the northeast. Hence system lies close To the ridge which favours northward movement. The low level Convergence along with low level relative vorticity has increased during Past 24 hrs. The sea surface temperature is about 30C. The sea height Anomaly is about 20-25m. However, the vertical wind shear of horizontal wind Is moderate to high (15-25 kts). It is low to the northeast of the system. The Mjo lies over phase 1 with negligible amplitude.. It is not favourable for Intensification.

Most of the nwp models suggest northward movement during next 48 hrs Across bangladesh. They suggest maintenance of depression intensity till Landfall by evening of today and gradual weakening thereafter.

[euro6208]

THE AREA OF CONVECTION PREVIOUSLY LOCATED NEAR 20.7N 89.4E
IS NOW LOCATED NEAR 21.3N 88.9E, APPROXIMATELY 80 NM SOUTH-SOUTHEAST
OF KOLKATA, INDIA. ANIMATED MULTISPECTRAL SATELLITE IMAGERY AND A
290920Z SSMI 37 GHZ IMAGE DEPICT A CONSOLIDATING LOW-LEVEL
CIRCULATION CENTER (LLCC) WITH IMPROVED DEEP CONVECTIVE BANDING OVER
THE SOUTH QUADRANT WRAPPING INTO THE EAST QUADRANT OF A WELL-DEFINED
LLCC. UPPER LEVEL ANALYSIS INDICATES MODERATE TO STRONG (20 TO 30
KNOTS) VERTICAL WIND SHEAR (VWS) OFFSET BY GOOD POLEWARD OUTFLOW.
CONVECTIVE DEVELOPMENT, ESPECIALLY OVER THE NORTHERN SEMI-CIRCLE, IS
HINDERED BY INTERACTION WITH LAND; HOWEVER, THERE IS A SLIGHT
POSSIBILITY THE SYSTEM MAY INTENSIFY FURTHER AS IT TRACKS SLOWLY
NORTHWARD AND REMAINS SITUATED NEAR THE BAY OF BENGAL FOR THE NEXT
DAY. THE AVAILABLE DYNAMIC MODELS INDICATE SLIGHT INTENSIFICATION
OVER THE NEXT DAY UNTIL THE SYSTEM TRACKS INTO SOUTHERN BANGLADESH.
MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 25 TO 30 KNOTS.
MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1000 MB. THE
POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE
WITHIN THE NEXT 24 HOURS IS UPGRADED TO MEDIUM.

[euro6208]

THE AREA OF CONVECTION PREVIOUSLY LOCATED NEAR 21.3N
88.9E, IS NOW LOCATED NEAR 21.6N 88.7E, APPROXIMATELY 55 NM SOUTH-
SOUTHEAST OF KOLKATA, INDIA. ANIMATED INFRARED SATELLITE IMAGERY
DEPICTS A CONSOLIDATING LOW-LEVEL CIRCULATION CENTER (LLCC) THAT HAS
BEEN NEARLY STATIONARY, JUST OFF THE COAST OF INDIA, WITH DEEP
CONVECTIVE BANDING WRAPPING IN THE SOUTHERN SEMI-CIRCLE. A 291343Z
SSMIS MICROWAVE IMAGE REVEALS A TIGHTLY WRAPPED SYSTEM THAT HAS
MAINTAINED CONVECTIVE BANDING DESPITE THE PROXIMITY TO LAND. UPPER
LEVEL ANALYSIS INDICATES MODERATE TO STRONG (20 TO 30 KNOTS)
VERTICAL WIND SHEAR (VWS) WHICH IS BEING OFFSET BY GOOD POLEWARD
OUTFLOW. DYNAMIC MODEL GUIDANCE INDICATES THE SYSTEM WILL TRACK
NORTH, OVER LAND, IN THE NEXT 12 HOURS AND WEAKEN DUE TO THE LAND
INTERACTION. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 25 TO
30 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1000
MB. DUE TO THE WELL DEFINED AND TIGHTLY WRAPPED NATURE OF THE
SYSTEM, THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL
CYCLONE WITHIN THE NEXT 24 HOURS REMAINS MEDIUM.