March 2013 Nor'easter by the Numbers
A two-day coastal storm left flooded streets but no widespread damage.
Photos
Pdfs
So how bad was the flooding from this week's coastal storm?
The new tide gauge recently installed at the Bayside Center on the bay between Fifth and Sixth streets provides a great resource for determining exactly where the storm falls in comparison to others.
The gauge showed a high reading of 4.49 feet at 4:06 a.m. on Thursday, March 7. That puts tide levels from this week's storm less than a foot below the damaging November 2009 nor'easter but almost three feet below October's record Superstorm Sandy.
The tide readings are based on 1988 datum, which is the first column of the chart below. These readings show tide levels above and below an average mid-tide.
The middle column of the chart is based on 1929 datum and matches the base flood elevation criteria that Ocean City property owners know from their flood insurance elevation certificates.
The third column in the chart above represents tide levels above an average low tide (mean low water). These are typically the readings people hear when weather forecasters talk about storm surge.
| NAVD 1988 | NGVD 1929 | Mean Low Water | |
| 100-Year Storm | 8.75 | 10.00 | 11.52 |
| Sandy, Oct. 29, 2012 | 7.25 | 8.50 | 10.02 |
| 1944 Hurricane | 6.65 | 7.90 | 9.42 |
| Storm of March 1962 | 6.35 | 7.60 | 9.12 |
| Dec. 11, 1992 Storm | 6.23 | 7.48 | 9.00 |
| Oct. 31, 1991 Storm | 6.00 | 7.25 | 8.77 |
| Gloria, Sept. 27, 1985 | 5.75 | 7.00 | 8.52 |
|
Nov. 11-14, 2009 Storm |
5.25 | 6.50 | 8.02 |
| 10-Year Storm | 5.05 | 6.30 | 7.82 |
| March 2013 Storm | 4.49 | 5.74 | 7.26 |
| Typical High Tide | 2.00 | 3.25 | 4.77 |
|
Matches |
Matches Flood Elevation Certificate |
Matches Most Weather Reports |
Six feet above mean low water generally signifies "minor flooding," seven feet "moderate flooding" and eight feet "major flooding."
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See and bookmark the tide gauge here.
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Some other numbers from this week's storm:
- Top wind speed in Ocean City: 61 mph (measured at 59th Street)
- High and low temperatures nearby: 41 and 33 (Atlantic City International)
- Rainfall: .83 inches
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Read more:
Ocean City Weathers Strong Coastal Storm
Storm Update: Wind, Waves and Tides Threaten Ocean City
Wind and Flooding Keeping Firefighters Busy
Video: Nor'easter Begins to Hit Ocean City
Pat
8:53 am on Friday, March 8, 2013
What does 100 year storm and 10 year storm mean on the chart??
Douglas Bergen
9:15 am on Friday, March 8, 2013
The 100-year storm is a hypothetical designation also known as base flood elevation or BFE (the height storm waters have a 1 percent chance of reaching in any given year as determined by the Federal Emergency Management Agency). That number is in flux and the subject of much debate right now. :)
Bob
9:15 am on Friday, March 8, 2013
Pat,
I'm no longer commenting here as people will believe what they want to believe, but I'll answer this one.
The 100 year storm and 10 year storm are recurrance intervals, or think of them as the the percent that a given flood can happen in a year.
For example, a 100 year flood has a 1 in 100 chance of occuring in a given year, or a 1% chance [ (1/100)*100].
A 10 year flood has a 1 in 10 chance of occuring in a given year, or a 10% chance.
Unfortunately, the USGS hasn't mapped every single Nor'Easter ever, but I'm pretty confident this was a fairly typical event on a tide chart - most likely falling right in or close to the mean tidal height for a nor'easter. Having lived through many of them, it didn't seem to be any better or worst than other ones.
Your recurrance probabilities are usually calculated by listing flood heights and ranking them - the more data, the more accurate (you need at least 10 years of data, but 100+ would be more accurate). You can see the short comings in this, however. It is based on what has happened, not what will happen. The 100 year storm elevation will not be the same in 10,20,30,40 years (it will change due to rising sea levels and storm frequency)- it should constantly be recalculated. Unfortunately, FEMA can't release new maps every year, so they have to make maps based on what it is currently and sit on them for 20 years or so. Hope this helps.
Eric Sauder
4:56 pm on Friday, March 8, 2013
Bob I appreciate your informative posts. You're looking at historical data. Looking at any data is a good thing. But what concerns people on the south end is the condition of the beaches now (particularly post Sandy) and the increased threat of flooding and property damage due to severe beach erosion (and not if it occurred in the past.) A secondary issue is the viability of their beaches for tourism.
What you seem to be saying is this isn't anything out of the ordinary historically and I can appreciate that. Whether its a blip or a natural cycle or signifies something different for the future really isn't the issue for them. And I don't think it's an unwillingness to believe what you're saying (it isn't on my part.) It's the reality of the condition of those beaches now that they're concerned with.
So thanks for the information you provided. Hope this helps.
Pat
9:36 am on Monday, March 11, 2013
Thank you for the information. I am paying more attention to matters such as this as my south end home sustained damage during the storm.;
Bob
9:35 am on Friday, March 8, 2013
Here are some recurrance interval tables from NOAA from the tide station in the inlet of Atlantic City. Keep in mind the method of tide height (MHHW, MLLW - you have to make sure you look at things on the correct scale) they're using and that 1m = 3.281ft:
Seasonal recurrance intervals:
http://tidesandcurrents.noaa.gov/est/seasonal.shtml?stnid=8534720
Extreme water levels:
http://tidesandcurrents.noaa.gov/est/est_station.shtml?stnid=8534720
Notice the positive slope. This goes back to the last paragraph of my first post.
Relative to mean sea level:
http://tidesandcurrents.noaa.gov/est/stickdiagram.shtml?stnid=8534720
And, annual exceedence probability:
http://tidesandcurrents.noaa.gov/est/curves.shtml?stnid=8534720
Richard Lee
10:07 am on Friday, March 8, 2013
Doug, thanks for the excellent reporting, as usual! Your report referenced wind speed recorded at 59th St. Do you know where the data gathered on that tower is recorded? Is it accessible on-line? Ever since that pole went up a couple of years ago I have always wondered who is recording the data and if I could monitor it as well. Thanks again for a great job.
Douglas Bergen
10:16 am on Friday, March 8, 2013
Unfortunately, the data from the 59th Street device is not posted for the public. I have to get the info from the city's emergency management coordinator (Frank Donato). NBC40 meteorologist Dan Skeldon also routinely reports O.C. wind speeds from there.
chuck betson
10:31 am on Friday, March 8, 2013
doug you do a tremendous service to the citizens of ocean city
walt hays
10:55 am on Friday, March 8, 2013
You can wind speed at the OCNJ Primary School here:http://weather.weatherbug.com/NJ/Ocean%20City-weather.html
EXiT REALTY OCEAN CITY
11:03 am on Friday, March 8, 2013
Doug, I agree. Thanks for doing a great job of always keeping everyone informed. Keep up the good work.
Joseph Landicini Broker 1301 West A-1 OCNJ 609-525-9901 Ext 14
Lisa Anderson Yoskin
11:35 am on Friday, March 8, 2013
Yes thank you! Stuck with only being a part time resident, but look forward to all the updates. Only been involved with OC for 2 years, but can any one tell me if the weather has been more servere then normal. In 2 years been through 2 hurracanes and a couple Nor'easters, along with some crazy freak storm that popped up around July 4th this last summer. Is that the norm?
Bob
2:17 pm on Friday, March 8, 2013
Lisa,
I'll try to answer this, the short answer is no, it is not statistical trend. Two years of activity even on the time scale that people have been living in Ocean City is not significant. Ocean City was founded 134 years ago - 2 years is 1.5% of that time. Climate is cyclical. There was a lot of storm activitity in the middle 80s until the early 90s, and then things calmed down a little bit. Look at the tide chart again and some of the records - in addition to a few big nor'easters, you had Hurricane Gloria in 1985 and Hurricane Bob in 1990 looked to be a threat. Hurricanes over the last 30 years or so occured less frequently than than they had previously.
Your recurrance intervals are based on long term data sets which 'smooth' the cycles out. If you were to break down flooding and storm frequency in ten year increments, you'll see certain decades were more 'active' than others. This appears to be a period of higher activity, but the 90s were a period of lower activity.
That being said, climate change will shift some things around, but it won't be overnight - it's not going to be 'starting next year ___ will happen'. It's a gradual change and what happens depends on what model you look at, but they all do agree that storms will become more frequent, it's just hard to say how much 'more' is 'more'.
Sko Hayes
5:39 pm on Saturday, March 9, 2013
Thanks for the information and the pictures on the storm, Doug. I'm way out here in Kansas and you're my only link to what's happening in OC!