Forecast Discussion 9/27

In the Atlantic, TD-8 has dissipated, while a low probability of development continues to be associated with 3 systems in the East Pacific. NHC does have a low probability of development for the remains of TD-8.

Sat Imagery shows that ex TD-8 has been completely sheared away to the northeast, however the surface circulation (now just a wave based on QuickSCAT) is moving west. Upper level winds continue to be unfavorable, so even though SSTs should increase as the wave moves west, development seems very unlikely. Pouch tracking continues to turn the system towards the north, and kill it. Steering winds support this forecast, but if it continues to lack any convection, it could instead simply continue to move west. Regardless of the exact track, upper level winds are likely to remain unfavorable, especially if it takes a more W than NW track.

Elsewhere in the Atlantic, PG-31 continues to push west along the ITCZ. Pouch tracking is having difficulty continuously tracking the system through the forecast period for all 3 models, but none seem to kill it outright in the next 3 days. Additionally, no global models develop this system.

In the Pacific, 2 systems appear to have the potential for development. 90E and an unnamed broad area of thunderstorms, both along the ITCZ. NHC also has ex-Nora listed as an area of low potential for development, but Nora is in an unfavorable environment and development seems very unlikely. 90E appears less organized today, though a 13Z QuickSCAT pass still showed a closed circulation. The unnamed system does not have a closed circulation yet. The last mesoscale runs for 90E are from 18Z yesterday, and still showed a potential for development at least into a TS, but they have not been run since that time because the Invest was taken off. It may have since been replaced, but no runs are available yet. Global models do not really do much with 90E. However, global models do unanimously develop the unnamed system to the east. Even the GFS at least develops a closed low, although it is much less defined today relative to yesterday's runs. On the other hand, the CMC shows some of the strongest development I have seen in any model this month. AS is usually the case, NGP takes the middle ground. A model consensus appears to be that development into a TD could occur in the next 72 hours in the vicinity of 110W, 15N, with tracks varying wildly depending on how much the system develops after that.