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Go Back   SailNet Community > Skills and Seamanship > Seamanship & Navigation > Thunderstorm in Chesapeake Bay
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Topic Review (Newest First)
07-29-2012 07:10 PM
pdqaltair
Re: Thunderstorm in Chesapeake Bay

Quote:
Originally Posted by SVAuspicious View Post
Okay I don't think we're communicating effectively. Let's start again.

I sail the bottom paint off my boat on Chesapeake Bay. I'm a professional delivery skipper and sail client boats a LOT.

In my experience people exaggerate wind speeds and wave height. That just is.

When I see a water spout (not terribly often on the Bay) I sail on a perpendicular course to the apparent track (radar is your friend) and haven't had one cross over me yet, so I don't see those winds. Spouts don't usually stay down over creeks and coves so you won't see them in most anchorages on the Bay; perhaps South Anchorage in Annapolis (maybe) or behind Tighlman (maybe).

For the run of the mill Chesapeake thunderstorm that might gust into the 40s that you let sneak up on you (bad on you) dumping the sheets keeps things under control while you roll up the jib and get the main under control. We're only talking about 20 or 30 minutes. There aren't many people out for a sustained weather system on the Bay.

Offshore is a different matter of course, but on the Bay there are so many places that it does make sense to duck into it's only the afternoon (sometimes morning the last couple of years) thunderstorm of short duration that sailors have to be ready for.

Fair enough?
Fair enough.
07-29-2012 06:16 PM
SVAuspicious
Re: Thunderstorm in Chesapeake Bay

Quote:
Originally Posted by pdqaltair View Post
From one-day Chesapeake data, for example, we could clearly determine that there has never been a tornado on the Chesapeake Bay. Foolishness, we would all agree, because they are short term and very localized. Many of us have seen waterspouts where wind speeds over 120 mph certainly existed. Wind gusts are like that too, often effecting areas of only hundred yards. Your data analysis is rather limited and your conclusions different from weather authorities.
Okay I don't think we're communicating effectively. Let's start again.

I sail the bottom paint off my boat on Chesapeake Bay. I'm a professional delivery skipper and sail client boats a LOT.

In my experience people exaggerate wind speeds and wave height. That just is.

When I see a water spout (not terribly often on the Bay) I sail on a perpendicular course to the apparent track (radar is your friend) and haven't had one cross over me yet, so I don't see those winds. Spouts don't usually stay down over creeks and coves so you won't see them in most anchorages on the Bay; perhaps South Anchorage in Annapolis (maybe) or behind Tighlman (maybe).

For the run of the mill Chesapeake thunderstorm that might gust into the 40s that you let sneak up on you (bad on you) dumping the sheets keeps things under control while you roll up the jib and get the main under control. We're only talking about 20 or 30 minutes. There aren't many people out for a sustained weather system on the Bay.

Offshore is a different matter of course, but on the Bay there are so many places that it does make sense to duck into it's only the afternoon (sometimes morning the last couple of years) thunderstorm of short duration that sailors have to be ready for.

Fair enough?
07-29-2012 01:53 PM
pdqaltair
Re: Thunderstorm in Chesapeake Bay

Quote:
Originally Posted by SVAuspicious View Post
The only data point on Chesapeake Bay was 66 kts at Tolchester Beach. Thomas Point didn't see anything like that. There was more wind inshore. I do give more credence to NWS data than CWOS data.

I didn't see anything over 40 kts on the boat in Back Creek.
Stingray point was 71 knots, about 3 times the wind energy you saw in harbor. Plenty to damage a boat with much canvas up. Several weather service articles confirm that gusts in excess of 100 knot have been recorded in other places.

From one-day Chesapeake data, for example, we could clearly determine that there has never been a tornado on the Chesapeake Bay. Foolishness, we would all agree, because they are short term and very localized. Many of us have seen waterspouts where wind speeds over 120 mph certainly existed. Wind gusts are like that too, often effecting areas of only hundred yards. Your data analysis is rather limited and your conclusions different from weather authorities.

So yeah, they are rare. If you are fortunate and chose your sailing days with caution, it is very likely you will complete your life without a violent expereince.
07-29-2012 12:19 PM
SVAuspicious
Re: Thunderstorm in Chesapeake Bay

The only data point on Chesapeake Bay was 66 kts at Tolchester Beach. Thomas Point didn't see anything like that. There was more wind inshore. I do give more credence to NWS data than CWOS data.

I didn't see anything over 40 kts on the boat in Back Creek.
07-29-2012 11:00 AM
pdqaltair
Re: Thunderstorm in Chesapeake Bay

Quote:
Originally Posted by SVAuspicious View Post
Can you show NOAA or Skywarn data to substantiate 80-90 kts? I haven't seen any data like that.
Oh please.... You're just being silly.

http://www.erh.noaa.gov/phi/storms/2...%20Derecho.pdf

From NOAA, gust reported up to 87 knots. Certainly NOAA and any prudent person would assume that higher gust occurred at places that were not monitored, a simple matter of statistics.

We're not discussing little people, we're discussing a very rare but very powerful event.
07-29-2012 10:20 AM
bandaidmd
Re: Thunderstorm in Chesapeake Bay

[QUOTE=travlineasy;862810]There have been several studies on this, but the easiest one I know of to read is http://edis.ifas.ufl.edu/pdffiles/SG/SG07100.pdf

one of the posters commented on the powerboat between two masts getting hit.
In the above linked study I found this quote quite amazing, "Every
year there are multiple deaths of boaters in open boats
caused by lightning strikes, but very few reports of
sailors in sailboats killed by lightning." just goes to show how little we really understand about lightning.
07-29-2012 02:51 AM
trevorN
Re: Thunderstorm in Chesapeake Bay

Quote:
Originally Posted by btrayfors View Post
Once in my favorite bar in Ft. Liquordale I watched one of Florida's notorious afternoon thunderstorms hit adjacent Bahia Mar marina. There were tons of big and small yachts there. A small powerboat, sandwiched between two very large sailboats with very tall masts, took a direct hit! The sailboats were untouched. I had another Mt. Gay and coke and pondered that for awhile.
Maybe God doesn't like stinkpots?
07-23-2012 02:39 PM
paperbird
Re: Thunderstorm in Chesapeake Bay

We're also out of HHN. Guess I should be thankful we were anchored out for the 'great derecho of '12.' See you around the dock, Andrewoliv.
07-23-2012 02:27 PM
andrewoliv
Re: Thunderstorm in Chesapeake Bay

I saw 66 on my wind gauge at HHN in Deale, MD
07-23-2012 02:14 PM
paperbird
Re: Thunderstorm in Chesapeake Bay

Here are some data from the path of the storm. Note that other locations had it much than we.

- 2:54 p.m. Fort Wayne International Airport IN records a wind gust to 91 m.p.h.
- 10:35 p.m. Automatic weather reporting station at the USGS in Reston, Va., measures a wind gust at 79 m.p.h
- 10:48 p.m. A weather observer at Ronald Reagan National Airport records a wind gust of 70 m.p.h. as the storm moves into District of Columbia.
- 10:50 - 10:58 p.m. Several automatic weather reporting stations in Prince George's County, Md. record wind gusts between 60 and 80 miles per hour. A wind gust of 76 m.p.h. was recorded in Seat Pleasant, Md
- 11:05 p.m. Baltimore-Washington International Airport observers report a peak wind gust of 66 m.p.h. at the height of the storm

We were anchored in Mill Creek by Solomons for the show. Our anecdotal observation is that the wind strength was not as high as reported. My totally non-scientific conjecture is that the system was moving so quickly that the velocity gradient was pretty significant with much higher winds at mast height and above than at deck level. We were also tucked up against the west bank of the creek and so were reasonably protected by the trees on the bank. Still managed to get our adrenaline up a good bit!
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