Schweizer Sturmforum

en ce début de matinée de mardi, le T.M.S semble se réorganiser quelque peu. Une large bande convective, dominante jusqu'à hier se déconnecte à présent du système et est positionnée entre l'ouest de la Suisse et le delta du Rhône.

****** Tropical storm 01M/99L ******

SUMMARY: 8th NOV. 2011, 0600 UTC
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LOCATION...41.5N 5.8E
ABOUT 108 NM...200 KM SE OF MARSEILLE
ABOUT 126 NM...233 KM W OF AJACCIO, CORSICA
MAXIMUM SUSTAINED WINDS...52 MPH...83 KM/H
PRESENT MOVEMENT...ROUGHLY 5KM/H TO THE EAST
MINIMUM CENTRAL PRESSURE... ROUGHLY 1000 hPa

UPDATE 06UTC: The center of the cyclone again became better organized with the strongest convection now in the southern and eastern part (maybe enhanced by the jet streak, which passes by to the SE). Some slow movement to the east occurred but despite a further consolidating cyclone, latest reports do not indicate any strengthening (also assisted by ASCAT data). No further surface reports were available.

NOTE 1: Despite issuing new ESTOFEX updates, this part of the outlook will be updated when new informations become available. Please check this table for further updates during the upcoming 24 hours.

NOTE 2: ESTOFEX is not responsible for forecasting any tropical storm activity. This is just an additional information and therefore captured as a "side-note". For more informations, please contact the following address of the Satellite Analysis Branch (http://www.ssd.noaa.gov/PS/TROP/2011/bu ... .html,[SAB]).

As of 18 UTC (7th Nov.), the Satellite Analysis Branch upgraded the depression over the W-Mediterranean to "Tropical system 01M", as convection persisted for an adequate time atop the center. Since then, deep convection weakened somewhat with warming cloud tops next to the center. Nevertheless, very good banding is now present in all quadrants with good outflow atop (especially to the NE, pointing to a 30 m/s 300 hPa jet). A Dvorak number-pressure relation was used for the pressure classification (also at 21Z at the 7th, a ship at position N 41°36' , E 6°06' reported a pressure of 1005.0 mb with 38kt winds from 160°). The final wind strength reflects the intensity of the latest SAB guidance.

There remains some time left for further intensification, before geopotential heights slowly increase during the end of the forecast period. We would not be surprised to see another flare-up of DMC along the center due to the convective cycle of those features (peaking during the morning hours). The N-outflow may weaken somewhat as the upper jet to the north weakens, but at the same time the southern outflow channel could take profit of a 300 hPa streak, which crosses Sicily during the forecast from SW to NE. SSTs remain at or above 20°C, whereas 500 hPa temperatures gradually warm up 1-2K until 06Z. Combining all those effects, some further organization/strengthening is forecast if this system can support more convective bursts along the center before overall conditions become somewhat less favorable during the night hours onwards.

The storm motion is handeled badly by the models...without surprise. 01M is captured in a very weak steering flow and most models now show a system, which meanders around between the Balearic Islands and Corsica/Sardinia. In any case, residents along the adjacent coasts should keep a close eye on the further development of this feature as bands of strong convection may bring heavy downpours next to gusty winds.

A level 1 was issued not for the system itself (as we do not forecast tropical cyclone activity), but for the showers/thunderstorms, which accompany that cyclone. The level 1 covers heavy rainfall and strong to isolated severe wind gusts.