Is there anything that limits a hurricane’s size and wind speed? I know Catagory 5 hurricanes (winds 175 miles per hour and up)are very rare, but is it possible for a storm to reach 200 or even 250 mile per hour sustained winds, even as a once-in-a-five-hundred-year-event?
And re. hurricane size, I remember Floyd, for example, was quite large for a hurricane. How much bigger could it have gotten? Is the potential for tropical storm size limited? Can we, our children, or our grandchildren some day possibly see a hurricane double Floyd’s diameter or even larger?
Don’t F5 tornados have the highest recorded internal windspeeds?
Good question. I’m not sure how big the can get theoretically, but I would say 200mph sustained would be about all you can get, and even those are very rare and do not last long at that intensity. Super Typhoon Keith a few years back had winds above 170kts (195mph), and even Hurricane Mitch had winds in the 180mph area. Super Typhoon Tip is I believe the strongest cyclone ever (with regards to pressure), although Keith came close.
Secondly, every storm is different. Size does not equate to intensity. There are a good number of storms in the southern hemisphere that can get fairly strong (90mph or so), but be very small, maybe only a couple hundred miles or so. Size is related to several factors, most notably what type of storm it is, i.e. monsoon depression/trough type, or trade wind type. Most Atlantic hurricanes are of the previous definition, and hence are relatively large. Same with a good number of the western Pacific storms.
Lastly, to nitpick, Cat 5 storms have winds above 155mph. 
I’ve been trying to research this more at other sites, and I’ve come up empty. Most writing I see on this subject is based on what has been recorded instead of what possibly could be recorded. It seems theoretical meteorology is a science in its infancy.
Wind speed as a whole also appears to be a very murky area. Just how fast is wind capable of blowing? I’ve read where gusts during Hurricane Andrew were reported close to 200 miles per hour though the storm itself was only a strong catagory 3.
What’s driving the winds is the pressure gradient. The deeper the low, the faster the atmosphere is being pulled inward and (due to the C. E.) the more rapid the spin. The eye wall is essentially the diameter at which the inward force of the pressure gradient is offset by the centripetal acceleration. Once an eye forms the system can be powered by latent heat released by condensation. As the storm expands in diameter the pressure gradient drops, winds decrease and the low breaks up.
As long as you have access to lots of warm water the storm continues. Warmer water = greater evaporation rate = greater condensation at the ceiling = greater energy = lower pressure = faster winds. Obviously the closer you get to the equator the warmer the water gets, but the coriolis effect weakens as you approach the equator so it becomes difficult to maintain the tight rotation necessary to maintain the storm’s structure. Between 5 degrees N and S, the cyclone breaks up into individual T-storms. Above 20-30 degrees the water starts to cool.
The coriolis effect for a given latitude doesn’t change unless the Earth’s rotation rate changes. So given the extra-tropical ocean temps, the biggest storms we’ve seen are pretty near the maximum possible intensity. I think the lowest pressure recorded was Gilbert at 882 mB, but I could be wrong (feel free to correct me). Tornadoes can reach lower pressures and greater wind speeds but they are highly unstable critters.
Of course all bets are off as global warming brings warmer waters to higher latitudes…