Mets, can you expain this map?

[OuterBanker]

Found this at CSU. But could not find info on colors and numbers.

ie Found that I live in a 4 area (Dare Co NC) but 60 miles away Hampton Roads is a 156. Does this mean every four years as against every 156?

Anyway, thought that it was an interesting map. It also discerns between El Nino, Neutral and La Nina years.

[OuterBanker]

Whoops forgot to post site.

http://gis.coaps.fsu.edu/httpdocs/Rtrn.php

[OuterBanker]

Geeze day is not starting out right. FSU not CSU is where I found it. Credit where credit is due

[HURAKAN]

That area had a landfall in 156 years. The map shows an average return of tropical cyclones to an area.

[wxman57]

It appears that the map may only show direct landfalls, not just the center of a storm passing near or over an area. For example, many storms hit NC from the south then travel north across that area marked "156". But unless the storm hits the "156" area directly from the NE-E, then it doesn't count as a direct landfall. That's the only explanation which makes sense, anyway.

Found this statement below one of the reports:

The Return Frequency is calculated for landfalling Hurricanes only. The Hurricanes that come ashore in a nearby county and impact the county of interest are ignored. Also any Hurricane that moves through the county from another county or move from land to offshore are also ignored.

That supports my assumption that only direct landfalls are counted, not secondary passages. And it explains how you can have a "4" region immediately next to a "156" region.

[OuterBanker]

That was my assumption too. Unfortunately, this could lead to feeling safe in Hampton Roads with these numbers. The reality is that our little strip of sand does not take any punch out of storms as they head north. They may not get direct strikes but it might as well be if they strike the Outer Banks first without any hitting any real land mass. The same holds true for brushes with hurricanes. Cape Hatteras has received many close calls in which they have experienced hurricane conditions including the eye wall. But, because the eye itself did not cross it is not considered a strike. I think a more accurate map should be drawn in which the odds of receiving hurricane conditions are likely. Not just direct strikes.

[wxman57]

You can get those probabilities based on actual potential impact of specific winds from e-transit.org:

http://e-transit.org/hurricane/welcome.html

[somethingfunny]

That was my assumption too. Unfortunately, this could lead to feeling safe in Hampton Roads with these numbers. The reality is that our little strip of sand does not take any punch out of storms as they head north. They may not get direct strikes but it might as well be if they strike the Outer Banks first without any hitting any real land mass. The same holds true for brushes with hurricanes. Cape Hatteras has received many close calls in which they have experienced hurricane conditions including the eye wall. But, because the eye itself did not cross it is not considered a strike. I think a more accurate map should be drawn in which the odds of receiving hurricane conditions are likely. Not just direct strikes.

I think that after Isabel all those feelings of false security are probably gone from the Tidewater, but you're right I'd rather see a map of hurricane conditions' return periods as well.

[OuterBanker]

Thanks Wxman. I have read that before and failed to see the of tropical storm wind and hurricane wind probabilities sections before. I thought it was all landfall probs. Excellent reference from CSU. If thoroughly read you will notice the difference between landfall probs and wind gusts probs. Excellent, thanks. All should read.

[gatorcane]

Looked through the data/tables. They have FL with a 68% probability of being hit by at least one hurricane this season and 31% by a major hurricane which significantly higher than any other state in the U.S (not surprisingly of course). Climatology using a Poisson distribution indicates 51% and 21%, respectively.

I looked up my region (Zone 6), which includes SE FL. Of the 68%, there is a 40.7% chance this region will see a hit by a hurricane and a 21.3% chance by a major hurricane. Those numbers do seem quite high indeed but looking at the data, 2010 should be quite active so can see why those numbers are running higher than climatology suggests.

Thanks WxMan for the link, I have archived it.