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Tropical Storm 03W (Aere) Warning #17
Issued at 10/0900Z
Track map- www.usno.navy.mil
Prognostic reasoning- www.usno.navy.mil
Warning text- www.usno.navy.mil
My assessment(@11:30UTC)…. Currently the system has behaved as forecast by JTWC, it now lies in the Luzon strait as a weak Tropical storm, currently wind shear from an upper level trough is inhibiting further development, while the trough provides good pole ward outflow the wind shear profile associated with the upper level system and subsequent erosion of the western flank counter balances this by preventing uninhibited convection and development throughout. Out flow-except pole ward, [may] continue to diminish as the system travels further north coupled with increasing wind shear this will almost certainly ensure the system will not gain strength and will struggle to maintain current strength in the later TAU’s(48hrs+). While deep convection still exists in part of the LLCC(eastern) the upper level trough has suppressed the remainder(western), this is a negative for any further development-note it seems that convection in the eastern semi-circle has diminished over the past 6 hours(04:27UTC-10:17UTC), latest satellite(10:40UTC) illustrates this and it may indicate earlier dissipation due to a continued weakening of the system, convection continues close to the centre of the low level circulation and conditions may exist to protect the system from the dry air to the west, JTWC believes this to be true and correct(see warning text-it refers to Baroclinic zone being pushed northward , this effectively means cradling or cupping, hence protecting the system from the non-tropical environment, namely dry air, polar jet stream and high shear) but I am not shore at the current time of what is truly happening within the system, what may be occurring is a “shrinking” of the system, the intensity will remain but cloud cover and reach of the wind gusts will be reduced. Steering wind charts continue to indicate northerly/north easterly movement note; the system turned north easterly around 00:00UTC and at 05:00 UTC was continuing this movement as it rounded the subtropical ridge. As the system travels higher through the latitudes it will encounter strong westerly’s around Okinawa associated with interaction with Baroclinic zone(the end of cradling), These westerly’s will see the beginning of extra tropical transition happening , they could however completely dissipate the system earlier than forecast should they become stronger than currently predicted. Model consensus varies on the later track of the system but this is due to known inaccuracies for these models when predicting Tropical storm movement across colder sea surface temperatures and extra tropical transition, at the present time the JTWC track map is a good indication of the most likely track taken by this system. In my opinion however the system may in fact track along an even more easterly track than forecast due to the earlier arrival of the winds from the west. In summary Aere has met a relatively unfavorable set of circumstances for further development and missed the possible envelope for a more westerly track over mainland Japan, conditions still exist that are permissible for development but the system does not seem well placed to take advantage of these. This will be my last update on Aere unless things significantly change in the next 24 to 48 hours or in the latter TAU’s and it again becomes a possible (serious) threat to Japan(one last note: the system briefly weakened to a TD and was reclassified as one @ 00:00UTC and regained strength to a TS to be upgraded again @ 06:00UTC. At the current time with the forecast predictions seeming to be on the mark the system poses no serious risk to the Japanese mainland nor is it likely to even interact with it, even if interaction or an eventual crossing were to occur the sy
stem should be so significantly weakened that it will bring winds no greater than what have already been observed with other weather systems crossing the area since 11/03.