Winds Every Which Way
July 14, 2011
In the course my two and a half summers' sailing on the rivers, I've tried to amass a robust picture of how the winds are deflected by the ridges and buildings that surround the point. These efforts are summarized here. The summary is quite weak on winds from the East and I have had no experience of winds from the North East. So I watched with keen attention as the weather forecasts pointed to ENE winds on this Thursday.
The forecast in the morning was very encouraging. It called for winds of 7-8 mph from ENE through the day. They would make for pleasant, steady sailing. So I set off from our loft downtown on my bicycle. My route takes me along the Allegheny River and over the Sixth Street Bridge. It was already apparent then that something was wrong.
East North East winds should blow straight down the Allegheny River, which is aligned roughly ENE at the Point. However the flags on the Convention Center on the River's Southern shore seemed uncertain about the wind direction. Pausing at the center of the Sixth Street Bridge to measure the wind, it was worrisome to find erratic readings. They varied from no wind at all to weak winds in the 0-4 mph range possibly coming from the NNE.
This erratic pattern continued as I rode along the Northern shore of the Allegheny and then Ohio River, stopping here and there to measure the wind.
I arrived at the Newport Marina at around 11:30pm to find the Ohio River pretty much windless. The water was glassy, but here or there, I could see small puffs of wind moving over the water as raspy smudges. Sailors who have the misfortune to be becalmed are used to seeing this sort of water. They sit on the lifeless deck watching for those smudges and hoping that they come near to breathe some motion into the boat. No one wants to sail in waters this windless.
Here's a photo of the look of the water from the dock. The water is glassy at the front and puff of wind is approaching.
I stood at the end of the end of the dock with my wind gauge in hand and measured zero.
There seemed little choice. Today was not a sailing day. So I got back on my bicycle and headed home. It was disappointing. I'd lost a day on the rivers; and it was a gloriously warm summer day.
When I arrived at Heinz Field, I decided to stop and reappraise things. I started to notice more stirrings of the wind. I checked the conditions on my cell phone. One site was reporting winds from the East South East and another from the East. Yet the forecasts remained East North East. All that seemed very odd.
What mattered to me, however, were the conditions I could see in front of me. By now the winds seemed to revive and I could see a steady breeze over the water. "Let's sail," I said to myself.
Shortly after 1pm, I had my boat rigged and in the water. A gentle breeze, blowing downstream, carried me off into the river. They were not strong winds, but they were enough to enable me to make my way upstream.
Then the winds died. I sat dead in the water, trying to calculate if I had stalled in the channel where an hour or so before a huge barge had lumbered through. Then I gauged my position to determine if the current was carrying me off downstream.
Fortunately, the current was weak. The Ohio was flowing at about 10,000 cubic feet per second, which I estimated to be a mere 0.36 mph. That is about half a foot per second, which adds up to 30 feet per minute. However I doubt that linear speed. Over the next hour or so, I found myself repeatedly becalmed on the Ohio River for periods that may have been as long as 5 or 10 minutes; and I don't think I was losing 150-300 feet each time. Perhaps it was a half or a third of that.
For completeness, here are plots of the currents on the rivers: Ohio, Allegheny, Mon and Yough. These are weak currents and sailing this day was possible only because of their weakness.
The sail proceeded in this way. It took me an hour and twenty minutes to sail to the Point. That is likely the longest it has taken. The trip alternated between periods of calm, during which I'd sit cooking in the sun, and good breezes that momentarily set the boat shooting over the water and simultaneously cooled my over-heating brow.
The gps tracks tells the story:
The voyage starts in the upper left hand corner at the Newport Marina. The outbound track is the erratic zig zag, as I try to tack into the wind. It under-represents the times I spent becalmed, because they are just a red spot in one place on the second plot, which is color coded for speeds. There is enough red and orange to show the struggle.
The remainder of the sail was faster, but still quite baffling as far as wind and wind direction was concerned. Winds coming from what seemed like a North Easterly direction carried me along the Ohio and up the Mon as far as the Fort Pitt Bridge. Then I found steady winds blowing downstream from the East South East. That would not happen if the undeflected winds were from the East North East, for they would be blocked by the mass of the downtown buildings.
Then I rounded the Point and found myself becalmed again. I struggled slowly up the Allegheny to Forbes Field, with erratic winds all the way. Once I'd passed the Fort Duqesne Bridge, a Westerly wind of sorts blew me on a run up the Allegheny. Then my return came courtesy of wind blowing in the opposite direction.
By about 4pm, I was back the Point. The flags on Heinz Field and elsewhere were now showing a steady wind from the South East. This was my ticket home. The speed-coded gps plot shows me running straight home at 5-7 mph, my best speeds and most consistent winds of the day.
It was only later, once I could check the weather websites at home, that I realized that everyone was puzzled by the winds this day. To see it, here's the morning forecast:
Compare that with the measured conditions as reported the next day:
During the few hours that I sailed, they bounced around from East and East North East to South East and were often quite weak, dropping to 3 mph. These are, presumably, spot readings. I'd guess that conditions in between were jumping about, every which way. That would explain why I'd found two different reports at one time for the wind direction.
There's a similar pattern on the winds reported in the NOAA log of our hourly conditions. The relevant entries read:
11AM EDT JUL 14 2011 PTSUNNY 73 51 46 E12 30.10S .
12PM EDT JUL 14 2011 PTSUNNY 75 51 43 E8 30.09F .
1PM EDT JUL 14 2011 PTSUNNY 76 49 38 CALM 30.08F .
2PM EDT JUL 14 2011 PTSUNNY 79 49 34 E6 30.06F .
3PM EDT JUL 14 2011 PTSUNNY 79 48 33 VRB5 30.05F .
4PM EDT JUL 14 2011 PTSUNNY 80 47 31 S6 30.03F .
5PM EDT JUL 14 2011 PTSUNNY 81 46 29 VRB3 30.02F .
Decoding the abbreviations, we have:
11am East 12 mph
12pm East 8 mph
1pm Calm
2pm East 6 mph
3pm Variable 5 mph
4pm South 6 mph
5pm Variable 3 mph
That the forecasters were befuddled, or at least that their reports were befuddling, can be read off how their forecasts continued. At 5:25 pm, they reported winds at ESE at 3 mph, while the earlier forecast had been East at 6-7 mph. In spite of the clear shift to Southerly components, the forecast continued to call for East North East winds at 6pm.
In the end, I learned little of use for my summary of wind conditions. But I did learn again to be wary of weather forecasts. These forecasts seemed not to be corrected through the day when conditions failed to meet the predictions. I am left wondering how frequently the forecasts are updated.
Here are some photos taken underway.
I was not sure that I'd pass the West End Bridge at all. Then came a moment when I turned and saw the Point framed by the Bridge. At that moment, I knew I'd make it. I paused for this photo since the sight is just magnificent:
I stopped upstream on the Mon at the Mon Wharf for a short break, some water, more suncream and to cool my feet:
Once on the Allegheny, I saw a barge approaching. Since the wind had a habit of just dying, I sailed to the shore and furled my sail. It seemed a poor idea to risk getting becalmed in the main channel:
You can see the glassy, windless water.
John D. Norton
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