Monday, February 18, 2019

What the heck is a warm nose?

Note the red line at the btm as it moves from close to zero Celsius to warmer temps and then back to freezing with height!
In weather terms, a 'warm nose', in the winter time, is a layer of air at about 850 millibars or 5000 feet that is warmer than either the freezing air above or below it. It can cause problems associated with any precipitation that might fall through it resulting, for example in snow reaching that level and then melting only to begin to refreeze as it get closer to the ground. The result, generally, is some form of sleet, but can become freezing rain if other conditions permit. So when a weather forecaster is talking about a warm nose of air moving into colder air, he or she is tacitly warning the viewer about possible forms of precipitation that would be different from rain or snow, i.e. some form of ice.

Will Forsyth MO area Parks flood in 2019?

Forsyth MO. - I was very much looking forward to a few new features in my small town of Forsyth Missouri in southwest Missouri this coming spring. A new bridge over Bull Shoals, a new roundabout and two parks that all looked to be in great shape!

But wait! There might be a fly in the ointment and that was the potential for both River Run and Shadowrock Parks to be flooded out early in the coming 2019 season! How could this happen, you ask?
Click to expand
Well, my fears grew somewhat when I realized that the water levels in Bull Shoals as well as the other two reservoirs (Beaver and Table Rock Lakes) upstream of it were much higher than they normally were (see graphic above). And with the spring season not even here, I noted that River Run was already becoming invaded on its northwestern shore! I just could not see how the Corps of engineers were going to manage their way out of flooding problems even if we have a typical amount of rain in March and April. (Perhaps they were hoping for a mini drought to occur....).

Graphic 2
As I considered the situation, and the fact that our rainfall had not been all that excessive over past six months (graphic 2), I turned my focus on the Bull Shoals dam down by the Arkansas border. I had to guess that they were simply unable to release as much water as they normally would possibly due to the time of year, when water absorbing foliage was not present. (Either that was the case or there were other issues occurring somewhere between that point and the gulf that I was unaware of...).

Whatever, the answer to the flooding question was going to resolve itself over the next couple of months, of that I was certain, I was just hoping for a chance to get in some 'Park' time early in the spring before anything of a wet nature happened.

Monday, February 11, 2019

Worst case scenario for Table Rock Dam!

The worst-case scenario of a catastrophic floodwater discharge from Table Rock Lake using the auxiliary floodgates would roughly resemble this: 

Water Level at 931 Feet:  Table Rock Lake is at full flood capacity. The ten Tainter gates are opened to accommodate additional lake inflow from the White River Basin including the James River and Beaver Lake discharge.

Water Level at 937 feet: Table Rock Lake is now 6 feet above flood capacity. The ten Tainter gates are opened wider in an effort to stabilize reservoir rise. Outflow from the Lake under these circumstances will be nearing 200-300 thousand cubic feet per second (CFS).

Water Level at 942 feet: Table Rock Lake is 11 feet above flood capacity and at its "design pool", or the maximum elevation that the reservoir is engineered to reach, under "probable maximum flood" scenarios. The dam’s ten Tainter gates will be fully raised to their maximum height of approximately 30 feet letting loose 550 thousand CFS into Lake Taneycomo. This scenario would effectively submerge and destroy the powerhouse, power transmission grid, hatchery, and wreak serious destruction down stream. An illustration of how Table Rock’s ten spillways might appear under these circumstances mimics this: the floodgates will extend up and out from the structure, like eyebrows, shadowing the concrete spillways!

Water Level at 947 feet: Table Rock Dam would be at its maximum capacity and water would be at the very top of the dam. The auxiliary spillway would be brought online, in concert with Table Rock’s fully opened floodgates. This catastrophic or "last resort" protocol releases 1 million CFS of lake waters into Taneycomo and deals dreadful destruction to Branson, Hollister, Point Lookout and possibly the Powersite Dam. At this point there is a danger of water overtopping the concrete dam and breaching the earthen structure, which imminently leads to cataclysmic structural failure and the uncontrolled release of the Table Rock Lake impoundment—nearly 3 million CFS of water.

Historically, Table Rock Lake has experienced a record crest of 935.47 feet, which occurred on April 27, 2011.

In December 2015, the dam released 72,000 CFS at its peak. This is the highest amount ever released! [Information source: https://en.wikipedia.org/wiki/Table_Rock_Lake]

Sunday, February 10, 2019

Potential for flooding in 2019 at Bull Shoals!


Forsyth MO. - Some mid February 2019 observations concerning the chances for seeing Bull Shoals flood once again. I got interested in watching the rainfall rates very early in the season as we were still in the middle of winter.  Above is a graphic that shows the current water level of the Bull Shoals Lake in feet above mean sea level. The other two historical lines concerned the levels in 2015 and 1017 -  two years that witnessed flooding levels that also meant that both the Shadowrock and River Run Parks remained closed for the summer and fall seasons. Last year, River Run was closed due to the construction of a new bridge, but many local folks and vacationers were hoping for a chance to enjoy both parks if they could remain high and dry!

I planned to follow up on this post from time to time, especially as we got more into the meat of the spring season. I noted that back in 2015, the level started going up in early March while the 2017 season had a later start. When and if the water rises above 670 some flooding of River Run would occur. Shadowrock, being at a slightly heavier elevation would then flood once the water rose over the 675 foot mark. That’s as best I can remember at any rate.

Feb 11, 2019 - A good bit of rain fell overnight and also looked to continue for much of Monday as a system slowly made its way off to the east. Beginning Tuesday, Feb 12, I plan to post the water levels at the two main reservoirs that are upstream of Bull Shoals. Below is a graphic of the levels on Feb 11. So, stay turned.

[All three of the lakes were at or above full power pools. Beaver was.33 feet above, Table Rock was .61 feet above and Bull Shoals was 1.91' above.]

Feb 12, 2019



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