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老農民版夜神月|2021-3-27 06:04
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本帖最後由 老農民版夜神月 於 2021-3-27 06:25 編輯
MFR新報維持此系統發展至中度熱帶風暴以上強度的概率為中AWIO20 FMEE 261242
TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE
BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER IN
THE SOUTHWEST INDIAN OCEAN
DATE: 2021/03/26 AT 1200 UTC
PART 1:
WARNING SUMMARY:
Nil.
PART 2 :
TROPICAL WEATHER DISCUSSION:
The basin is in a monsoon trough (MT) configuration between 50 and 75E centered between 8S and 10S. Further east, a Near Equatorial Trough (NET) pattern persists with westerlies just south of the equator. The convective activity is moderate in the flows slowing down area but also near the two suspect areas located east of Agalega and in the Australian AoR.
In the Australian region:
Located near 10.7S/91.0E according to the BoM at 06UTC, the system is still weak given to the latest scatterometer data. The 0833Z SSMI swath shows that the convective activity is shallow near the center.
Despite a good upper level divergence, this minimum is restrained by a moderate westerly shear bringing dry air, and a lack of surface convergence. Indeed, over the next few days, the circulation should progressively lose its equatorial feeding due to the strengthening of the westerlies and their bending towards the northern hemisphere (Kelvin wave + MRG) but also due to the lack of surface convergence on the polar side north of a deep trough. This minimum should disappear in the next few days over the extreme east of our area of responsibility.
Development of a moderate tropical storm over the easternmost parts of our basin is not expected anymore.
East of Agalega:
Thanks to good feeding on the equatorial side (20/25kt monsoon flow) and to a lesser extent on the polar side, the suspect area between Agalega and Diego-Garcia is showing signs of development with increasing curvature in the cloud pattern. Nevertheless, according to partial ASCAT data and high resolution satellite images, it seems that the inner core of the circulation is still quite broad. A swirl of clouds rotating around a center drowned in the convective mass, can be seen around 9.4S/66.6E at 11Z.
This system does not benefit from particularly favorable conditions. Despite a good feeding on the equatorial side, the trade wind flow is weak on the far edge of the subtropical ridge. A weak to moderate easterly shear also seems to limit the potential for development at shorter range. On Sunday, while the trade wind flow is strengthening with the arrival of the new high-pressure cell to the south, the surface convergence on the northern side is weakening, with the westerly flow bending towards the northern hemisphere (Kelvin wave + MRG). Mid next week, on the edge of the NET, the system could find a more conducive environment for its deepening. But for now, the main guidance is now keen to significantly deepen that low, especially those of NOAA. IFS in its last run still suggest gale force winds on Sunday.
The risk of development of a moderate tropical storm, south-west of the Chagos Islands is moderate up to Monday, and then low from Tuesday.
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