14 September 2012

Nadine recurving as Global Hawk surveys its environment

Nadine has been on the TS-hurricane threshold (60kts) for about 36 hours now, and probably won't change much in the coming days as it recurves to the north and begins its extratropical transition. 

Track guidance is in good agreement on a path toward the Azores in about 6 days, perhaps as a hurricane, perhaps as a tropical storm, or perhaps as a potent extratropical storm (somewhere in the 50-70kt ballpark by the time it reaches the islands).  The NHC 5-day forecast is shown by the thick green line, while various models are shown by the thin multi-colored lines.  The Azores islands are labeled for reference.

The big NASA field program, HS3, is sending the Global Hawk unmanned aircraft to survey Nadine today, releasing 69 dropsondes in a 15x15 degree "lawnmower pattern" around the storm to get a detailed picture of the near-storm environment.  The state-of-the-art plane took off from Wallops at 10:00am EDT this morning, and will fly over Nadine until tomorrow morning at 6:15am.

Aside from Nadine, the basin is amazingly quiet for the second week of September.  There is an easterly wave centered right on the African coast that some global models (e.g. GFS and FIM) develop ever so slightly, while the others show it doing nothing.  We certainly have time to watch it and see if it's worth another mention.

The ACE (Accumulated Cyclone Energy) stands at 80.6 as of this morning, which is about 139% of what an average season would be at on this date.  This time of year, every day without a hurricane (or multiple hurricanes for that matter) lets 2012's ACE loose ground against the average because climatologically, ACE racks up real fast in mid-September.  We're very close to the ACE we had in 2010 and 2011 on this date.

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