Tropical Storm 04A

Force Thirteen



Location: 15.5N 71.3E

Max Sustained: 40mph

Minimum Pressure: 1000mb

Satellite imagery indicates that the low pressure has increased in organization and colder convective cloud tops can be seen flaring, albeit displaced slightly to the southwest due to shear. A recent microwave imagery pass also indicated a well defined closed low level circulation center, based on this data the system has been upgraded to Tropical Storm 04A, the initial intensity remains at 35kts due to satellite imagery and ASCAT data. The system is expected to drift slowly to the east for about the next 12-18 hours before a ridge that builds in over India begins to send the system westward. Models have become somewhat more clear in resolving the track, and the original eastward drift and there is now higher confidence in a mostly westward track over the Arabian Sea, and the forecast track follows closely to the ECMWF ensemble mean and has overall good confidence. The environment surrounding the cyclone is currently marginal with moderate northeasterly wind shear. After the westward drift, wind shear is expected to weaken as well as the motion of the cyclone offsetting the shear vector as the system mostly “outruns” the shear. Warm sea surface temperatures of 28-29°C and high ocean heat content levels will lead to significant intensification. Due to the current shear and slow movement, only modest strengthening is forecasted through 48 hours, afterwards when forward speed increased and shear decreases, a faster strengthening, possibly rapid is likely. The system is forecasted to reach a peak intensity of 110knots at hour 96, with the possibility of a higher peak. After 96 hours, as dry air wraps around the periphery of the system and sea surface temps decrease some, slight weakening is shown at the end of the forecast period. The intensity forecast follows a blend of the GFS and ECMWF and has overall fair confidence.

It is very important for interests in western India, particularly around Mumbai to monitor the system closely as it will be within close proximity to the coastline within the next 48 hours or so; and the potential of moderate to heavy rainfall and gusty winds will persist through atleast 48 hours

It is too soon to determine exactly what the impacts could potentially be to the Arabian Peninsula. However it is important for interests to closely monitor the system and the progress of it, and the chances of the Arabian Sea being affected by a cyclone, potentially a powerful one just outside the forecast period, continues to increase.

INT… 35kts

12HRS… 35kts

24HRS… 40kts

36HRS… 45kts

48HRS… 50kts

72HRS… 85kts

96HRS… 110kts

120HRS… 100kts