See what the Discovery Channel Storm Chasers use:
http://dsc.discovery.com/videos/storm-chasers-behind-the-chase/
The equipment was selected for all the same reasons you list.
In the first video, "Storm Shooters 2010":
Part 1:
00:26 - Sony HVR-Z5
00:30 - "changing tapes in 8 cameras" (not flash memory or hard disc drive)
00:37 - in the distance, could be a HDR-FX1, HDR-FX1000 or HVR-Z1 (all use the same body and lenses)
00:39 - Ewa-Marine rain cape on a Sony-something with a mic fuzzy (aka: dead cat)
Low light = big lenses and imaging chips. This is true for storm chasing, music videos or movie production. The least expensive I would suggest is the Sony HDR-FX7.
You did not mention which Mac you are using. MiniDV tape camcorders will have you connecting a firewire cable (not USB) to the camcorder's DV port (not USB) and the Mac's firewire port (not USB). If you are using a MacBook Air or MacBook with no firewire port, and no way to add one, then you have the JVC GY-HM100 to investigate.
Fast action and lots of compression (AVCHD commonly found in consumer cam flash memory and hard disc drive high definition camcorders) don't get along well. Hard disc drives are a bad idea because of the knocking around. If, however, this is all that can be used in your budget, then the largest lenses and imaging chip combos will be in the Sony HDR-CX500 series and Canon HF S series - but being AVCHD onto flash memory, they are nowhere near where you should be.
I am looking to get a Camera to take storm chasing with me. I need something that works good in low light environments and takes fairly high quality video of clouds from a decent distance. Also I needs to be small and tough (the trip can be cramped and things get tossed around int eh heat of a chase) Id like to be able to edit the video after using Final Cut. A hard drive or flash memory would be great as it is less stuff to pack and potentially lose. Lastly I wold of course like something that is not extremely expensive, I am a poor college student after all. If anyone has any suggestions that would be great.

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